Introdução. Rupturas agudas do tendão de Aquiles afetam as propriedades mecânicas tendíneas. Estudos vêm preconizando o uso de mobilização precoce (tratamento acelerado) para evitar grandes prejuízos tendíneos. Entretanto, estudos que avaliem as propriedades mecânicas do tendão de Aquiles de humanos após ruptura total, submetidos à mobilização precoce, não foram encontrados na literatura específica da área. Objetivo: comparar as propriedades mecânicas e morfológicas do tendão de Aquiles entre pacientes submetidos a tratamento conservador e pacientes submetidos a tratamento acelerado (mobilização precoce) após a sutura do tendão de Aquiles. Materiais e Métodos: A amostra foi dividida intencionalmente em três grupos: controle (CTR; n=9), grupo conservador (CON; n=9; Pós-Cirúrgico: 28,3±3,6 meses) e grupo acelerado (ACE; n=9; Pós-Cirúrgico: 29,8±4,8 meses). Um dinamômetro isocinético foi utilizado para avaliação do torque dos grupos musculares flexores plantares e flexores dorsais do tornozelo. Foram obtidos os valores de área de secção transversa (AST) e comprimento do tendão (CT) de Aquiles. Para a avaliação da relação stress-strain os sujeitos realizaram duas contrações voluntárias máximas em rampa para flexão plantar no ângulo de 0º com duração de 10 segundos cada. Durante as duas contrações voluntárias máximas o deslocamento da JMT do músculo gastrocnêmio medial com o tendão de Aquiles foi verificado por meio de ultrassonografia utilizando uma sonda com arranjo linear. Simultaneamente a este procedimento, foi adquirido o sinal eletromiográfico do músculo tibial anterior, utilizado para a correção da força do tendão de Aquiles. As imagens necessárias para o cálculo do strain, bem como os sinais EMG e de torque foram sincronizados. Os valores máximos de stress, strain, força, deformação, módulo de Young, CT e AST foram comparados. Resultados: Não foram encontradas diferenças significativas nas propriedades mecânicas e morfológicas entre membros do grupo CTR. Não houve diferença significativa entre os membros saudáveis dos grupos CON e ACE e os do grupo CTR. Dessa forma, os membros saudáveis dos grupos CON e ACE foram utilizados como controle do membro lesão em ambos os grupos. Tanto no grupo CON, quanto no grupo ACE, o stress, a força e o módulo de Young apresentaram menores valores no membro lesionado, enquanto que o strain obtido em 10MPa e a AST foram maiores neste membro comparado ao contralateral saudável. Não houve diferença significativa no CT entre os membros, independente do grupo. Não foram encontradas diferenças significativas nas propriedades mecânicas, bem como na morfologia do tendão de Aquiles na comparação entre os membros lesionados dos grupos CON e ACE. Discussão: Esta maior complacência tendínea encontrada nos tendões lesados, independente do grupo, pode estar associada tanto as adaptações decorrentes da lesão que não recuperaram a níveis de normalidade, bem como a mudança nos hábitos de vida após a lesão. Além disso, o protocolo acelerado de reabilitação não foi capaz de reduzir as perdas advindas da ruptura tendínea. Tal resultado pode estar associado à especificidade do protocolo utilizado, que foi desenhado para ganho de flexibilidade no tornozelo e não para força muscular. Conclusão: Em um período mínimo de 21 meses de pós-operatório o tendão de Aquiles ainda apresenta efeitos deletérios da ruptura total nas propriedades estruturais e mecânicas do tendão. O protocolo de reabilitação utilizado não foi eficaz para a redução de tais efeitos. / Introduction. Acute Achilles tendon rupture affects the mechanical properties of the tendon. Despite the tendinous adaptations generated by decreased use, few studies have used early weight bearing (accelerated treatment) to avoid the large losses in the musculoskeletal tissues. In addition, studies that evaluated the mechanical properties of human Achilles tendon after acute rupture, subjected to early weight bearing were not found. Purpose: to compare the mechanical and morphological properties of the Achilles tendon between patients undergoing conservative and accelerated treatment, after Achilles tendon suture. Materials and Methods: subjects were intentionally allocated into three groups: control (CTR; n=9), conservative treatment (CON; n=9; Postsurgical time: 28.3±3.6 months) and accelerated treatment (ACC; n=9; Postsurgical time: 29.8±4.8 months). An isokinetic dynamometer was used to evaluate the torque production of ankle dorsi- and plantar-flexor muscles. The values of Achilles tendon cross sectional area (CSA) and length were obtained. To evaluate the stress-strain relation, patients were asked to produce two isometric maximal voluntary contractions during a ramp protocol (angle: neutral position; duration: 10 seconds) of the plantar flexor muscles. During the maximal contractions the displacement of the myotendinous junction of the gastrocnemius medialis muscle was evaluated by ultrasound with a linear array probe. Simultaneously, the electromyography (EMG) signal of the tibialis anterior was recorded, and used to correct the Achilles tendon force. The ultrasound images, EMG signals and torque were synchronized. The maximal values of stress, strain, force, displacement, Young’s modulus, tendon length and CSA were compared. Results: there were no significant differences in the morphological and mechanical properties between limbs in the CTR group. Moreover, there were no significant differences in the morphological and mechanical properties between healthy limbs amongst groups. Thus, the healthy limbs of the CON and ACC groups were used as control of the injured limb. In CON and ACC groups the stress, force and Young’s modulus had lower values in the injured limb compared to the contralateral healthy limb, while the strain obtained at 10MPa and the CSA were higher in the injured limb. There were no significant differences in the tendon length between groups and limbs. Moreover, there were no significant differences in the morphological and mechanical properties between injured limbs (CON and ACC). Discussion: The highest tendinous compliance found on the injured tendons, independent of the group might be associated to both the adaptations due to injury that did not return to normal healthy levels and to possible changes in the daily life activities after injury. In addition, the accelerated treatment was unable to reduce the losses due to tendon rupture. These results might be associated to the specificity of the rehabilitation protocol used that was designed for the gain of flexibility and not for strength gains. Conclusion: Twenty-one months post-surgery were unable to recover the deleterious effects of acute Achilles tendon rupture on the structural and mechanical tendon properties. The accelerated rehabilitation protocol was ineffective to reduce these deleterious effects.

Introdução. Rupturas agudas do tendão de Aquiles afetam as propriedades mecânicas tendíneas. Estudos vêm preconizando o uso de mobilização precoce (tratamento acelerado) para evitar grandes prejuízos tendíneos. Entretanto, estudos que avaliem as propriedades mecânicas do tendão de Aquiles de humanos após ruptura total, submetidos à mobilização precoce, não foram encontrados na literatura específica da área. Objetivo: comparar as propriedades mecânicas e morfológicas do tendão de Aquiles entre pacientes submetidos a tratamento conservador e pacientes submetidos a tratamento acelerado (mobilização precoce) após a sutura do tendão de Aquiles. Materiais e Métodos: A amostra foi dividida intencionalmente em três grupos: controle (CTR; n=9), grupo conservador (CON; n=9; Pós-Cirúrgico: 28,3±3,6 meses) e grupo acelerado (ACE; n=9; Pós-Cirúrgico: 29,8±4,8 meses). Um dinamômetro isocinético foi utilizado para avaliação do torque dos grupos musculares flexores plantares e flexores dorsais do tornozelo. Foram obtidos os valores de área de secção transversa (AST) e comprimento do tendão (CT) de Aquiles. Para a avaliação da relação stress-strain os sujeitos realizaram duas contrações voluntárias máximas em rampa para flexão plantar no ângulo de 0º com duração de 10 segundos cada. Durante as duas contrações voluntárias máximas o deslocamento da JMT do músculo gastrocnêmio medial com o tendão de Aquiles foi verificado por meio de ultrassonografia utilizando uma sonda com arranjo linear. Simultaneamente a este procedimento, foi adquirido o sinal eletromiográfico do músculo tibial anterior, utilizado para a correção da força do tendão de Aquiles. As imagens necessárias para o cálculo do strain, bem como os sinais EMG e de torque foram sincronizados. Os valores máximos de stress, strain, força, deformação, módulo de Young, CT e AST foram comparados. Resultados: Não foram encontradas diferenças significativas nas propriedades mecânicas e morfológicas entre membros do grupo CTR. Não houve diferença significativa entre os membros saudáveis dos grupos CON e ACE e os do grupo CTR. Dessa forma, os membros saudáveis dos grupos CON e ACE foram utilizados como controle do membro lesão em ambos os grupos. Tanto no grupo CON, quanto no grupo ACE, o stress, a força e o módulo de Young apresentaram menores valores no membro lesionado, enquanto que o strain obtido em 10MPa e a AST foram maiores neste membro comparado ao contralateral saudável. Não houve diferença significativa no CT entre os membros, independente do grupo. Não foram encontradas diferenças significativas nas propriedades mecânicas, bem como na morfologia do tendão de Aquiles na comparação entre os membros lesionados dos grupos CON e ACE. Discussão: Esta maior complacência tendínea encontrada nos tendões lesados, independente do grupo, pode estar associada tanto as adaptações decorrentes da lesão que não recuperaram a níveis de normalidade, bem como a mudança nos hábitos de vida após a lesão. Além disso, o protocolo acelerado de reabilitação não foi capaz de reduzir as perdas advindas da ruptura tendínea. Tal resultado pode estar associado à especificidade do protocolo utilizado, que foi desenhado para ganho de flexibilidade no tornozelo e não para força muscular. Conclusão: Em um período mínimo de 21 meses de pós-operatório o tendão de Aquiles ainda apresenta efeitos deletérios da ruptura total nas propriedades estruturais e mecânicas do tendão. O protocolo de reabilitação utilizado não foi eficaz para a redução de tais efeitos. / Introduction. Acute Achilles tendon rupture affects the mechanical properties of the tendon. Despite the tendinous adaptations generated by decreased use, few studies have used early weight bearing (accelerated treatment) to avoid the large losses in the musculoskeletal tissues. In addition, studies that evaluated the mechanical properties of human Achilles tendon after acute rupture, subjected to early weight bearing were not found. Purpose: to compare the mechanical and morphological properties of the Achilles tendon between patients undergoing conservative and accelerated treatment, after Achilles tendon suture. Materials and Methods: subjects were intentionally allocated into three groups: control (CTR; n=9), conservative treatment (CON; n=9; Postsurgical time: 28.3±3.6 months) and accelerated treatment (ACC; n=9; Postsurgical time: 29.8±4.8 months). An isokinetic dynamometer was used to evaluate the torque production of ankle dorsi- and plantar-flexor muscles. The values of Achilles tendon cross sectional area (CSA) and length were obtained. To evaluate the stress-strain relation, patients were asked to produce two isometric maximal voluntary contractions during a ramp protocol (angle: neutral position; duration: 10 seconds) of the plantar flexor muscles. During the maximal contractions the displacement of the myotendinous junction of the gastrocnemius medialis muscle was evaluated by ultrasound with a linear array probe. Simultaneously, the electromyography (EMG) signal of the tibialis anterior was recorded, and used to correct the Achilles tendon force. The ultrasound images, EMG signals and torque were synchronized. The maximal values of stress, strain, force, displacement, Young’s modulus, tendon length and CSA were compared. Results: there were no significant differences in the morphological and mechanical properties between limbs in the CTR group. Moreover, there were no significant differences in the morphological and mechanical properties between healthy limbs amongst groups. Thus, the healthy limbs of the CON and ACC groups were used as control of the injured limb. In CON and ACC groups the stress, force and Young’s modulus had lower values in the injured limb compared to the contralateral healthy limb, while the strain obtained at 10MPa and the CSA were higher in the injured limb. There were no significant differences in the tendon length between groups and limbs. Moreover, there were no significant differences in the morphological and mechanical properties between injured limbs (CON and ACC). Discussion: The highest tendinous compliance found on the injured tendons, independent of the group might be associated to both the adaptations due to injury that did not return to normal healthy levels and to possible changes in the daily life activities after injury. In addition, the accelerated treatment was unable to reduce the losses due to tendon rupture. These results might be associated to the specificity of the rehabilitation protocol used that was designed for the gain of flexibility and not for strength gains. Conclusion: Twenty-one months post-surgery were unable to recover the deleterious effects of acute Achilles tendon rupture on the structural and mechanical tendon properties. The accelerated rehabilitation protocol was ineffective to reduce these deleterious effects.

Introdução. Rupturas agudas do tendão de Aquiles afetam as propriedades mecânicas tendíneas. Estudos vêm preconizando o uso de mobilização precoce (tratamento acelerado) para evitar grandes prejuízos tendíneos. Entretanto, estudos que avaliem as propriedades mecânicas do tendão de Aquiles de humanos após ruptura total, submetidos à mobilização precoce, não foram encontrados na literatura específica da área. Objetivo: comparar as propriedades mecânicas e morfológicas do tendão de Aquiles entre pacientes submetidos a tratamento conservador e pacientes submetidos a tratamento acelerado (mobilização precoce) após a sutura do tendão de Aquiles. Materiais e Métodos: A amostra foi dividida intencionalmente em três grupos: controle (CTR; n=9), grupo conservador (CON; n=9; Pós-Cirúrgico: 28,3±3,6 meses) e grupo acelerado (ACE; n=9; Pós-Cirúrgico: 29,8±4,8 meses). Um dinamômetro isocinético foi utilizado para avaliação do torque dos grupos musculares flexores plantares e flexores dorsais do tornozelo. Foram obtidos os valores de área de secção transversa (AST) e comprimento do tendão (CT) de Aquiles. Para a avaliação da relação stress-strain os sujeitos realizaram duas contrações voluntárias máximas em rampa para flexão plantar no ângulo de 0º com duração de 10 segundos cada. Durante as duas contrações voluntárias máximas o deslocamento da JMT do músculo gastrocnêmio medial com o tendão de Aquiles foi verificado por meio de ultrassonografia utilizando uma sonda com arranjo linear. Simultaneamente a este procedimento, foi adquirido o sinal eletromiográfico do músculo tibial anterior, utilizado para a correção da força do tendão de Aquiles. As imagens necessárias para o cálculo do strain, bem como os sinais EMG e de torque foram sincronizados. Os valores máximos de stress, strain, força, deformação, módulo de Young, CT e AST foram comparados. Resultados: Não foram encontradas diferenças significativas nas propriedades mecânicas e morfológicas entre membros do grupo CTR. Não houve diferença significativa entre os membros saudáveis dos grupos CON e ACE e os do grupo CTR. Dessa forma, os membros saudáveis dos grupos CON e ACE foram utilizados como controle do membro lesão em ambos os grupos. Tanto no grupo CON, quanto no grupo ACE, o stress, a força e o módulo de Young apresentaram menores valores no membro lesionado, enquanto que o strain obtido em 10MPa e a AST foram maiores neste membro comparado ao contralateral saudável. Não houve diferença significativa no CT entre os membros, independente do grupo. Não foram encontradas diferenças significativas nas propriedades mecânicas, bem como na morfologia do tendão de Aquiles na comparação entre os membros lesionados dos grupos CON e ACE. Discussão: Esta maior complacência tendínea encontrada nos tendões lesados, independente do grupo, pode estar associada tanto as adaptações decorrentes da lesão que não recuperaram a níveis de normalidade, bem como a mudança nos hábitos de vida após a lesão. Além disso, o protocolo acelerado de reabilitação não foi capaz de reduzir as perdas advindas da ruptura tendínea. Tal resultado pode estar associado à especificidade do protocolo utilizado, que foi desenhado para ganho de flexibilidade no tornozelo e não para força muscular. Conclusão: Em um período mínimo de 21 meses de pós-operatório o tendão de Aquiles ainda apresenta efeitos deletérios da ruptura total nas propriedades estruturais e mecânicas do tendão. O protocolo de reabilitação utilizado não foi eficaz para a redução de tais efeitos. / Introduction. Acute Achilles tendon rupture affects the mechanical properties of the tendon. Despite the tendinous adaptations generated by decreased use, few studies have used early weight bearing (accelerated treatment) to avoid the large losses in the musculoskeletal tissues. In addition, studies that evaluated the mechanical properties of human Achilles tendon after acute rupture, subjected to early weight bearing were not found. Purpose: to compare the mechanical and morphological properties of the Achilles tendon between patients undergoing conservative and accelerated treatment, after Achilles tendon suture. Materials and Methods: subjects were intentionally allocated into three groups: control (CTR; n=9), conservative treatment (CON; n=9; Postsurgical time: 28.3±3.6 months) and accelerated treatment (ACC; n=9; Postsurgical time: 29.8±4.8 months). An isokinetic dynamometer was used to evaluate the torque production of ankle dorsi- and plantar-flexor muscles. The values of Achilles tendon cross sectional area (CSA) and length were obtained. To evaluate the stress-strain relation, patients were asked to produce two isometric maximal voluntary contractions during a ramp protocol (angle: neutral position; duration: 10 seconds) of the plantar flexor muscles. During the maximal contractions the displacement of the myotendinous junction of the gastrocnemius medialis muscle was evaluated by ultrasound with a linear array probe. Simultaneously, the electromyography (EMG) signal of the tibialis anterior was recorded, and used to correct the Achilles tendon force. The ultrasound images, EMG signals and torque were synchronized. The maximal values of stress, strain, force, displacement, Young’s modulus, tendon length and CSA were compared. Results: there were no significant differences in the morphological and mechanical properties between limbs in the CTR group. Moreover, there were no significant differences in the morphological and mechanical properties between healthy limbs amongst groups. Thus, the healthy limbs of the CON and ACC groups were used as control of the injured limb. In CON and ACC groups the stress, force and Young’s modulus had lower values in the injured limb compared to the contralateral healthy limb, while the strain obtained at 10MPa and the CSA were higher in the injured limb. There were no significant differences in the tendon length between groups and limbs. Moreover, there were no significant differences in the morphological and mechanical properties between injured limbs (CON and ACC). Discussion: The highest tendinous compliance found on the injured tendons, independent of the group might be associated to both the adaptations due to injury that did not return to normal healthy levels and to possible changes in the daily life activities after injury. In addition, the accelerated treatment was unable to reduce the losses due to tendon rupture. These results might be associated to the specificity of the rehabilitation protocol used that was designed for the gain of flexibility and not for strength gains. Conclusion: Twenty-one months post-surgery were unable to recover the deleterious effects of acute Achilles tendon rupture on the structural and mechanical tendon properties. The accelerated rehabilitation protocol was ineffective to reduce these deleterious effects.

Ballistic fabrics made from high performance polymeric fibers such as Kevlar®, Twaron® and Spectra® fibers and composites utilizing these fabrics are among the leading materials for modern body armor systems. Polymeric fibers used to produce ballistic fabrics often behave viscoelastically and exhibit time- and rate-dependent stress-strain relations. This necessitates the study of the constitutive behavior of composites filled by ballistic fabrics. Rheological models based on discrete rheological components (including spring and dashpot) have been widely used to study the viscoelastic behavior of polymeric fabrics. Such rheological (or viscoelasticity) models are qualitatively useful in understanding the effects of various micro-mechanisms and molecular features on the macroscopic responses of ballistic fabrics. In the present work, the constitutive behavior of Twaron CT709® fabric/natural rubber (Twaron®/NR) composite is studied using three viscoelasticity models (i.e., a four-parameter Burgers model, a three-parameter generalized Maxwell (GMn=1) model, a five-parameter generalized Maxwell (GMn=2) model) and a newly developed para-rheological model. The new model utilizes a three-parameter element to represent the Twaron® fabric and the affine network based molecular theory of rubber elasticity to account for the deformation mechanisms of the NR constituent. The uniaxial stress-strain relation of the Twaron®/NR composite at two constant strain rates is experimentally determined. The values of the parameters involved in all the models are extracted from the experimental data obtained in this study. The stress-relaxation response (under a uniaxial constant strain) and the creep deformation (under a uniaxial constant stress) of the composite are also experimentally measured. The three viscoelasticity models considered here are capable of predicting the viscoelastic constitutive behavior of the composite with different levels of accuracy. The stress-strain relation at each strain rate predicted by the newly developed para-rheological model is seen to be in good agreement with the measured stress-strain curve over the entire strain range studied. It is shown that the new model also predicts the elastic moduli and ultimate stress of the Twaron®/NR composite well. All the four models are found to predict the initial relaxation response of the composite fairly well, while the long-term stress relaxation is more accurately represented by the para-rheological model. An implicit solution provided by the para-rheological model is shown to predict the creep response of the composite more accurately than all the other models at both the primary and secondary stages. The mathematical complexity that arises from including an additional Maxwell element to the GMn=1 model to obtain the GMn=2 model with enhanced predictability is traded with the use of simple characteristic time functions in the para-rheological model. These functions are found to greatly improve the predictability of the newly developed model for the stress relaxation modulus and creep compliance. This study also explores the utility of the para-rheological model as a tool to probe the micromechanisms and molecular features that are causally related to the macroscopically observed viscoelastic behavior of the composite. The relaxation and creep trends predicted by the para-rheological model indicate that the long time viscoelastic response of the composite lies between that of a crosslinked polymer and a semi-crystalline thermoplastic.

Stress-strain relations for unconfined and confined concrete are proposed to overcome some shortcomings of existing commonly used models. Specifically, existing models are neither easy to invert nor integrate to obtain equivalent rectangular stress-block parameters for hand analysis and design purposes. The stress?strain relations proposed are validated for a whole range of concrete strengths and confining stresses. Then, closed form expressions are derived for the equivalent rectangular stress-block parameters. The efficacy of the results is demonstrated for hand analysis applied for deriving the moment-curvature performance of a confined concrete column. Results are compared with those obtained from a computational fiber-element using the proposed stress-strain model and another widely used model; good agreement between the two is observed. The model is then utilized in the development of a new structural system that utilizes the positive attributes of timber and concrete to form a parallel. Timber has the advantage of being a light weight construction material, easy to handle, is environmentally friendly. However, large creep deflections and significant issues with sound transmission (the footfall problem) generally limit timber use to small spans and low rise buildings. Concrete topping on timber sub-floors mitigate some of these issues, but even with well engineered wood systems, the spans are relatively short. In this study, a new structural system called structural boxed-concrete, which utilizes the positive attributes of both timber and reinforced concrete to form a parallel system (different from timber-concrete composite system) is explored. A stress-block approach is developed to calculate strength and deformation. An analytical stress-block based moment-curvature analysis is performed on the timber-boxed concrete structural elements. Results show that the structural timber-boxed concrete members may have better strength and ductility capacities when compared to an equivalent ordinary reinforced concrete member.

Stress-strain relations for unconfined and confined concrete are proposed to overcome some shortcomings of existing commonly used models. Specifically, existing models are neither easy to invert nor integrate to obtain equivalent rectangular stress-block parameters for hand analysis and design purposes. The stress?strain relations proposed are validated for a whole range of concrete strengths and confining stresses. Then, closed form expressions are derived for the equivalent rectangular stress-block parameters. The efficacy of the results is demonstrated for hand analysis applied for deriving the moment-curvature performance of a confined concrete column. Results are compared with those obtained from a computational fiber-element using the proposed stress-strain model and another widely used model; good agreement between the two is observed. The model is then utilized in the development of a new structural system that utilizes the positive attributes of timber and concrete to form a parallel. Timber has the advantage of being a light weight construction material, easy to handle, is environmentally friendly. However, large creep deflections and significant issues with sound transmission (the footfall problem) generally limit timber use to small spans and low rise buildings. Concrete topping on timber sub-floors mitigate some of these issues, but even with well engineered wood systems, the spans are relatively short. In this study, a new structural system called structural boxed-concrete, which utilizes the positive attributes of both timber and reinforced concrete to form a parallel system (different from timber-concrete composite system) is explored. A stress-block approach is developed to calculate strength and deformation. An analytical stress-block based moment-curvature analysis is performed on the timber-boxed concrete structural elements. Results show that the structural timber-boxed concrete members may have better strength and ductility capacities when compared to an equivalent ordinary reinforced concrete member.

There is currently a knowledge gap regarding the plastic material properties of many steel types that Atlas Copco use in their high torque power tools. This makes it difficult to fully utilise the capabilities of the Finite Element Method (FEM) to aid the developmental process. Case hardened steel is of special interest as there is not any established method on how to model it numerically.Test specimens of steel type 9195 and 2541 has been developed with two different geometries; hollow and solid. Specimen were heat treated to create case hardened specimens with different Case Depths (CD) as well as specimens made to mimic the material behaviour of the case and core of case hardened steel.Monotone torsion tests were conducted to generate stress-strain data for material models. Hardness tests of case hardened steel were made to determine hardness profiles. By combining these results, a spatially dependent case hardened steel material in an FE-model was created.Test results of the homogeneous specimen tests were successfully modelled using FEA. The case hardened steel could also be modelled, but with a discrepancy against the test results as the model core material were not representative actual core. However, the spatially dependent material model has high potential for simulating the case hardened steel, given the correct inputs. / Det finns för närvarnade bristfällig kännedom gällandes plastiska materialegenskaper hos många av de stål Atlas Copco använder i sina högmomentsverktyg för åtdragning av förband. Detta gör det svårt att fullt ut använda finita elementmetoden (FEM) som ett verktyg i produkters utvecklingsprocess. Sätthärdat stål är av intresse då det inte finns någon etablerad metod för hur det ska modelleras numeriskt.Provstavar gjorda av ståltyperna 9195 och 2541 har tagits fram med två olika geometrier; ihåliga och solida. Provstavarna var värmebehandlade vilket gav sätthärdade material med olika sätthärdningsdjup samt provstavar i material som skulle efterlikna materialet hos höljet och kärnan av sätthärdat stål.Monotona vridprov utfördes för att generera spännings-töjningsdata för användning i materialmodeller. Hårdhetstester gjordes för att fastställa hårdhetsprofiler hos sätthärdat stål. Genom att kombinera dessa provresultat skapades en numerisk material-model av sätthärdat stål med FEM.Testresultaten från de homogena provstavarna återskapades numeriskt med goda resultat. De sätthärdade provstavarnas beteende kunde också återskapas, men med ett något bristfälligt resultat då kärnmaterialet hos modellen inte var representativt av riktigt kärnmaterial hos sätthärdat stål. Modellen har dock hög potential för att återskapa sätthärdat stål, givet korrekt materialdata.

No / The effect of matrix polymer and filler content on the rheological behavior of hydroxyapatite-filled injection molding grade high-density polyethylene (HDPE) has been studied. Studies of the flow curves revealed that the matrix and the composite exhibit three distinct regions in the flow curve, namely, a pseudoplastic region at low to moderate shear rates, a plateau and a second pseudoplastic region at high shear rates. The shear stress corresponding to the plateau (Tc) is dependent on both the filler concentration and the melt temperature. Addition of HA in the HDPE matrix increases the value of Tc and decreases compressibility of the melt. An increase in temperature also raises the value of Tc. From the nature of flow curves it is concluded that the matrix polymer largely decides the rheology of the composite.

In the present work, the load-bearing behaviour of Textile Reinforced Concrete (TRC), which is a composite of a fine-grained concrete matrix and a reinforcement of high-performance fibres processed to textiles, exposed to uniaxial tensile loading was investigated based on numerical simulations. The investigations are focussed on reinforcement of multi-filament yarns of alkali-resistant glass. When embedded in concrete, these yarns are not entirely penetrated with cementitious matrix, which leads associated with the heterogeneity of the concrete and the yarns to a complex load-bearing and failure behaviour of the composite. The main objective of the work was the theoretical investigation of effects in the load-bearing behaviour of TRC, which cannot be explained solely by available experimental results. Therefore, a model was developed, which can describe the tensile behaviour of TRC in different experimental test setups with a unified approach. Neglecting effects resulting from Poisson’s effect, a one-dimensional model implemented within the framework of the Finite Element Method was established. Nevertheless, the model takes also transverse effects into account by a subdivision of the reinforcement yarns into so-called segments. The model incorporates two types of finite elements: bar and bond elements. In longitudinal direction, the bar elements are arranged in series to represent the load-bearing behaviour of matrix or reinforcement. In transverse direction these bar element chains are connected with bond elements. The model gains most of its complexity from non-linearities arising from the constitutive relations, e. g., limited tensile strength of concrete and reinforcement, tension softening of the concrete, waviness of the reinforcement and non-linear bond laws. Besides a deterministic description of the material behaviour, also a stochastic formulation based on a random field approach was introduced in the model. The model has a number of advantageous features, which are provided in this combination only in a few of the existing models concerning TRC. It provides stress distributions in the reinforcement and the concrete as well as properties of concrete crack development like crack spacing and crack widths, which are in some of the existing models input parameters and not a result of the simulations. Moreover, the successive failure of the reinforcement can be studied with the model. The model was applied to three types of tests, the filament pull-out test, the yarn pull-out test and tensile tests with multiple concrete cracking. The results of the simulations regarding the filament pull-out tests showed good correspondence with experimental data. Parametric studies were performed to investigate the influence of geometrical properties in these tests like embedding and free lengths of the filament as well as bond properties between filament and matrix. The presented results of simulations of yarn pull-out tests demonstrated the applicability of the model to this type of test. It has been shown that a relatively fine subdivision of the reinforcement is necessary to represent the successive failure of the reinforcement yarns appropriately. The presented results showed that the model can provide the distribution of failure positions in the reinforcement and the degradation development of yarns during loading. One of the main objectives of the work was to investigate effects concerning the tensile material behaviour of TRC, which could not be explained, hitherto, based solely on experimental results. Hence, a large number of parametric studies was performed concerning tensile tests with multiple concrete cracking, which reflect the tensile behaviour of TRC as occurring in practice. The results of the simulations showed that the model is able to reproduce the typical tripartite stress-strain response of TRC consisting of the uncracked state, the state of multiple matrix cracking and the post-cracking state as known from experimental investigations. The best agreement between simulated and experimental results was achieved considering scatter in the material properties of concrete as well as concrete tension softening and reinforcement waviness. / Die vorliegende Arbeit beschäftigt sich mit Untersuchungen zum einaxialen Zugtragverhalten von Textilbeton. Textilbeton ist ein Verbundwerkstoff bestehend aus einer Matrix aus Feinbeton und einer Bewehrung aus Multifilamentgarnen aus Hochleistungsfasern, welche zu textilen Strukturen verarbeitet sind. Die Untersuchungen konzentrieren sich auf Bewehrungen aus alkali-resistentem Glas. Das Tragverhalten des Verbundwerkstoffs ist komplex, was aus der Heterogenität der Matrix und der Garne sowie der unvollständigen Durchdringung der Garne mit Matrix resultiert. Das Hauptziel der Arbeit ist die theoretische Untersuchung von Effekten und Mechanismen innerhalb des Lastabtragverhaltens von Textilbeton, welche nicht vollständig anhand verfügbarer experimenteller Ergebnisse erklärt werden können. Das entsprechende Modell zur Beschreibung des Zugtragverhaltens von Textilbeton soll verschiedene experimentelle Versuchstypen mit einem einheitlichen Modell abbilden können. Unter Vernachlässigung von Querdehneffekten wurde ein eindimensionales Modell entwickelt und im Rahmen der Finite-Elemente-Methode numerisch implementiert. Es werden jedoch auch Lastabtragmechanismen in Querrichtung durch eine Unterteilung der Bewehrungsgarne in sogenannte Segmente berücksichtigt. Das Modell enthält zwei Typen von finiten Elementen: Stabelemente und Verbundelemente. In Längsrichtung werden Stabelemente kettenförmig angeordnet, um das Tragverhalten von Matrix und Bewehrung abzubilden. In Querrichtung sind die Stabelementketten mit Verbundelementen gekoppelt. Das Modell erhält seine Komplexität hauptsächlich aus Nichtlinearitäten in der Materialbeschreibung, z.B. durch begrenzte Zugfestigkeiten von Matrix und Bewehrung, Zugentfestigung der Matrix, Welligkeit der Bewehrung und nichtlineare Verbundgesetze. Neben einer deterministischen Beschreibung des Materialverhaltens beinhaltet das Modell auch eine stochastische Beschreibung auf Grundlage eines Zufallsfeldansatzes. Mit dem Modell können Spannungsverteilungen im Verbundwerkstoff und Eigenschaften der Betonrissentwicklung, z.B. in Form von Rissbreiten und Rissabständen untersucht werden, was in dieser Kombination nur mit wenigen der existierenden Modelle für Textilbeton möglich ist. In vielen der vorhandenen Modelle sind diese Eigenschaften Eingangsgrößen für die Berechnungen und keine Ergebnisse. Darüber hinaus kann anhand des Modells auch das sukzessive Versagen der Bewehrungsgarne studiert werden. Das Modell wurde auf drei verschiedene Versuchstypen angewendet: den Filamentauszugversuch, den Garnauszugversuch und Dehnkörperversuche. Die Berechnungsergebnisse zu den Filamentauszugversuchen zeigten eine gute Übereinstimmung mit experimentellen Resultaten. Zudem wurden Parameterstudien durchgeführt, um Einflüsse aus Geometrieeigenschaften wie der eingebetteten und freien Filamentlänge sowie Materialeigenschaften wie dem Verbund zwischen Matrix und Filament zu untersuchen. Die Berechnungsergebnisse zum Garnauszugversuch demonstrierten die Anwendbarkeit des Modells auf diesen Versuchstyp. Es wurde gezeigt, dass für eine realitätsnahe Abbildung des Versagensverhaltens der Bewehrungsgarne eine relativ feine Auflösung der Bewehrung notwendig ist. Die Berechnungen lieferten die Verteilung von Versagenspositionen in der Bewehrung und die Entwicklung der Degradation der Garne im Belastungsverlauf. Ein Hauptziel der Arbeit war die Untersuchung von Effekten im Zugtragverhalten von Textilbeton, die bisher nicht durch experimentelle Untersuchungen erklärt werden konnten. Daher wurde eine Vielzahl von Parameterstudien zu Dehnkörpern mit mehrfacher Matrixrissbildung, welche das Zugtragverhalten von Textilbeton ähnlich praktischen Anwendungen abbilden, durchgeführt. Die Berechnungsergebnisse zeigten, dass der experimentell beobachtete dreigeteilte Verlauf der Spannungs-Dehnungs-Beziehung von Textilbeton bestehend aus dem ungerissenen Zustand, dem Zustand der Matrixrissbildung und dem Zustand der abgeschlossenen Rissbildung vom Modell wiedergegeben wird. Die beste Übereinstimmung zwischen berechneten und experimentellen Ergebnissen ergab sich unter Einbeziehung von Streuungen in den Materialeigenschaften der Matrix, der Zugentfestigung der Matrix und der Welligkeit der Bewehrung.

In the present work, the load-bearing behaviour of Textile Reinforced Concrete (TRC), which is a composite of a fine-grained concrete matrix and a reinforcement of high-performance fibres processed to textiles, exposed to uniaxial tensile loading was investigated based on numerical simulations. The investigations are focussed on reinforcement of multi-filament yarns of alkali-resistant glass. When embedded in concrete, these yarns are not entirely penetrated with cementitious matrix, which leads associated with the heterogeneity of the concrete and the yarns to a complex load-bearing and failure behaviour of the composite. The main objective of the work was the theoretical investigation of effects in the load-bearing behaviour of TRC, which cannot be explained solely by available experimental results. Therefore, a model was developed, which can describe the tensile behaviour of TRC in different experimental test setups with a unified approach. Neglecting effects resulting from Poisson’s effect, a one-dimensional model implemented within the framework of the Finite Element Method was established. Nevertheless, the model takes also transverse effects into account by a subdivision of the reinforcement yarns into so-called segments. The model incorporates two types of finite elements: bar and bond elements. In longitudinal direction, the bar elements are arranged in series to represent the load-bearing behaviour of matrix or reinforcement. In transverse direction these bar element chains are connected with bond elements. The model gains most of its complexity from non-linearities arising from the constitutive relations, e. g., limited tensile strength of concrete and reinforcement, tension softening of the concrete, waviness of the reinforcement and non-linear bond laws. Besides a deterministic description of the material behaviour, also a stochastic formulation based on a random field approach was introduced in the model. The model has a number of advantageous features, which are provided in this combination only in a few of the existing models concerning TRC. It provides stress distributions in the reinforcement and the concrete as well as properties of concrete crack development like crack spacing and crack widths, which are in some of the existing models input parameters and not a result of the simulations. Moreover, the successive failure of the reinforcement can be studied with the model. The model was applied to three types of tests, the filament pull-out test, the yarn pull-out test and tensile tests with multiple concrete cracking. The results of the simulations regarding the filament pull-out tests showed good correspondence with experimental data. Parametric studies were performed to investigate the influence of geometrical properties in these tests like embedding and free lengths of the filament as well as bond properties between filament and matrix. The presented results of simulations of yarn pull-out tests demonstrated the applicability of the model to this type of test. It has been shown that a relatively fine subdivision of the reinforcement is necessary to represent the successive failure of the reinforcement yarns appropriately. The presented results showed that the model can provide the distribution of failure positions in the reinforcement and the degradation development of yarns during loading. One of the main objectives of the work was to investigate effects concerning the tensile material behaviour of TRC, which could not be explained, hitherto, based solely on experimental results. Hence, a large number of parametric studies was performed concerning tensile tests with multiple concrete cracking, which reflect the tensile behaviour of TRC as occurring in practice. The results of the simulations showed that the model is able to reproduce the typical tripartite stress-strain response of TRC consisting of the uncracked state, the state of multiple matrix cracking and the post-cracking state as known from experimental investigations. The best agreement between simulated and experimental results was achieved considering scatter in the material properties of concrete as well as concrete tension softening and reinforcement waviness. / Die vorliegende Arbeit beschäftigt sich mit Untersuchungen zum einaxialen Zugtragverhalten von Textilbeton. Textilbeton ist ein Verbundwerkstoff bestehend aus einer Matrix aus Feinbeton und einer Bewehrung aus Multifilamentgarnen aus Hochleistungsfasern, welche zu textilen Strukturen verarbeitet sind. Die Untersuchungen konzentrieren sich auf Bewehrungen aus alkali-resistentem Glas. Das Tragverhalten des Verbundwerkstoffs ist komplex, was aus der Heterogenität der Matrix und der Garne sowie der unvollständigen Durchdringung der Garne mit Matrix resultiert. Das Hauptziel der Arbeit ist die theoretische Untersuchung von Effekten und Mechanismen innerhalb des Lastabtragverhaltens von Textilbeton, welche nicht vollständig anhand verfügbarer experimenteller Ergebnisse erklärt werden können. Das entsprechende Modell zur Beschreibung des Zugtragverhaltens von Textilbeton soll verschiedene experimentelle Versuchstypen mit einem einheitlichen Modell abbilden können. Unter Vernachlässigung von Querdehneffekten wurde ein eindimensionales Modell entwickelt und im Rahmen der Finite-Elemente-Methode numerisch implementiert. Es werden jedoch auch Lastabtragmechanismen in Querrichtung durch eine Unterteilung der Bewehrungsgarne in sogenannte Segmente berücksichtigt. Das Modell enthält zwei Typen von finiten Elementen: Stabelemente und Verbundelemente. In Längsrichtung werden Stabelemente kettenförmig angeordnet, um das Tragverhalten von Matrix und Bewehrung abzubilden. In Querrichtung sind die Stabelementketten mit Verbundelementen gekoppelt. Das Modell erhält seine Komplexität hauptsächlich aus Nichtlinearitäten in der Materialbeschreibung, z.B. durch begrenzte Zugfestigkeiten von Matrix und Bewehrung, Zugentfestigung der Matrix, Welligkeit der Bewehrung und nichtlineare Verbundgesetze. Neben einer deterministischen Beschreibung des Materialverhaltens beinhaltet das Modell auch eine stochastische Beschreibung auf Grundlage eines Zufallsfeldansatzes. Mit dem Modell können Spannungsverteilungen im Verbundwerkstoff und Eigenschaften der Betonrissentwicklung, z.B. in Form von Rissbreiten und Rissabständen untersucht werden, was in dieser Kombination nur mit wenigen der existierenden Modelle für Textilbeton möglich ist. In vielen der vorhandenen Modelle sind diese Eigenschaften Eingangsgrößen für die Berechnungen und keine Ergebnisse. Darüber hinaus kann anhand des Modells auch das sukzessive Versagen der Bewehrungsgarne studiert werden. Das Modell wurde auf drei verschiedene Versuchstypen angewendet: den Filamentauszugversuch, den Garnauszugversuch und Dehnkörperversuche. Die Berechnungsergebnisse zu den Filamentauszugversuchen zeigten eine gute Übereinstimmung mit experimentellen Resultaten. Zudem wurden Parameterstudien durchgeführt, um Einflüsse aus Geometrieeigenschaften wie der eingebetteten und freien Filamentlänge sowie Materialeigenschaften wie dem Verbund zwischen Matrix und Filament zu untersuchen. Die Berechnungsergebnisse zum Garnauszugversuch demonstrierten die Anwendbarkeit des Modells auf diesen Versuchstyp. Es wurde gezeigt, dass für eine realitätsnahe Abbildung des Versagensverhaltens der Bewehrungsgarne eine relativ feine Auflösung der Bewehrung notwendig ist. Die Berechnungen lieferten die Verteilung von Versagenspositionen in der Bewehrung und die Entwicklung der Degradation der Garne im Belastungsverlauf. Ein Hauptziel der Arbeit war die Untersuchung von Effekten im Zugtragverhalten von Textilbeton, die bisher nicht durch experimentelle Untersuchungen erklärt werden konnten. Daher wurde eine Vielzahl von Parameterstudien zu Dehnkörpern mit mehrfacher Matrixrissbildung, welche das Zugtragverhalten von Textilbeton ähnlich praktischen Anwendungen abbilden, durchgeführt. Die Berechnungsergebnisse zeigten, dass der experimentell beobachtete dreigeteilte Verlauf der Spannungs-Dehnungs-Beziehung von Textilbeton bestehend aus dem ungerissenen Zustand, dem Zustand der Matrixrissbildung und dem Zustand der abgeschlossenen Rissbildung vom Modell wiedergegeben wird. Die beste Übereinstimmung zwischen berechneten und experimentellen Ergebnissen ergab sich unter Einbeziehung von Streuungen in den Materialeigenschaften der Matrix, der Zugentfestigung der Matrix und der Welligkeit der Bewehrung.