No description available.

The present study reviews applications of FRP materials joined by structural adhesives in civil engineering. FE analysis with mix-mode cohesive zone material model (CZM) was used to analyze stresses induced in two structural adhesives joining dissimilar materials (concrete GFRP-CFRP) of the hybrid-composite unit. The predicted failure loads, displacements and deformation by the 3-D non-linear FE analysis in the present study are in good agreement with the experimental results of the hybrid-composite unit reported by Deskovic et al. (1995). The contact analysis revealed a complex 3-D state of stress in the bondlines of both structural adhesives. It is concluded that higher joint strength is expected when a ductile adhesive is used. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Abstract not available

Abstract not available

Osteoarthritis (OA) of the knee is a common condition. The condition causes pain and swelling in the knee joint and as a consequence knee range of motion, particularly knee extension, can be decreased. While a number of studies have indicated increases in knee extension range of motion (ROM) can be achieved following stretching interventions, these studies have been undertaken in young healthy populations mostly. To date, there have been no investigations of stretching as a single intervention in people with OA knee. Review of Literature: To gain an appreciation of the literature in this area, three structured literature reviews were undertaken. The first examined the efficacy of acute stretching interventions on lower limb joint ROM in young and elderly subjects, the second examined the efficacy of periodic muscle stretching interventions on lower limb joint ROM in elderly subjects and the third examined the efficacy of periodic muscle stretching interventions on ROM in subjects with OA of the knee joint. The results of the first review indicated that there is strong evidence for acute stretching interventions to increase joint ROM in the lower limb of young and elderly subjects. The results of the second review indicated that there is strong evidence for periodic stretching interventions to increase joint ROM in the lower limb of elderly subjects. The result of the third review indicated that there is limited evidence for stretching interventions alone to improve ROM in the lower limb in subjects with OA of the knee joint. As consequence of these findings two studies were designed to investigate the effects of acute and periodic stretching in people with OA of the knee joint. Study 1 Objective: The objective of this study was to investigate the effects of an acute hamstring-stretching programme on knee extension range of motion in individuals with osteoarthritis (OA) of the knee and compare them to individuals of a similar age without OA of the knee. Study Design: A cross sectional study design was used. Participants: Thirty one subjects (16 male and 15 female) with OA of the knee were recruited from the local population (mean age 67.8 yrs SD: 5.0, mass 81.4 kg, SD: 15.2, height 168.5 cm, SD 11.1). Thirty one subjects of a similar age (9 male and 23 female) were also recruited who were otherwise fit and healthy and did not have OA of the knee (mean age 68.8 yrs SD: 5.2, mass 71.4 kg, SD: 13.2, height 163.8 cm, SD 8.1). Method: Hamstring extensibility was assessed by a passive knee extension test using a Kincom® isokinetic dynamometer. Subjects undertook two trials of maximum knee extension. The Kincom® then stretched the hamstrings to a point determined as 80% of the initial maximum knee extension test. Three sets of 60 seconds stretching were undertaken with 60 seconds rest between sets. Two further maximal knee extension tests were performed after the stretching intervention. The variables of interests were maximal knee extension, peak passive torque and stiffness. Analysis: A 2-factor repeated measures ANOVA model was utilised. The alpha level was set at 0.05. Results: There was a significant main effect by time for knee extension ROM, peak passive torque and stiffness (p<0.05). There was no interaction effect between groups across time (p>0.05). Knee extension range of motion (ROM) in the OA group increased significantly from 75.6 (SD: 17.2) degrees to 80.5 (SD: 22.3) degrees after the intervention (p<0.05). Subjects in the non OA group increased significantly from 77.5 (SD: 15.5) degrees to 81.9 (SD: 18.2) degrees after the intervention (p<0.05). The knee extension ROM recorded at 50% of the peak torque level pre intervention for the OA group was 60.3 (SD: 18.7) degrees and this increased significantly to 67.2 (SD 16.7) degrees post intervention (p<0.05). For the non OA group, knee extension ROM at 50% of peak torque increased significantly from 60.1 (SD: 15.2) degrees to 65.8 (SD 16.0) degrees (p<0.05). Peak passive torque in the OA group increased significantly from 18.1 (SD: 9.6) Nm to 22.5 (SD: 12.9) Nm after the intervention (p<0.05). Subjects in the non OA group increased significantly from 21.05 (SD: 11.6) Nm to 22.05 (SD: 12.8) Nm after the intervention (p<0.05). For stiffness, there was a significant interaction effect (p <0.05) between groups across time. The OA group increased significantly from 0.70 (SD: 0.35) Nm/deg to 0.89 (SD: 0.5) Nm/deg after the intervention (p<0.05). Subjects in the non OA group increased significantly 0.78 (SD: 0.36) Nm/deg to 0.82 (SD: 0.42) Nm/deg after the intervention (p<0.05). Conclusions: The study demonstrated that knee extension ROM, passive resistive torque and stiffness increased with a single bout of stretching. These results indicate that both elderly subjects and those with degenerative joint disease are able to demonstrate immediate tissue adaptations with acute stretching interventions. This is important as clinicians often prescribe acute stretching exercises in the preparation for other activities such as strengthening and walking programmes. Improving joint range of motion prior to other subsequent activities may be beneficial to those people with OA in particular, as management guidelines for these populations recommend regular exercise to reduce the deterioration of the condition. Study 2 Objective: The purpose of this study was to investigate the effects of a six week stretching intervention to the key muscles of the lower limb, in people with osteoarthritis (OA) of the knee joint and compare them to individuals of a similar age without OA of the knee. A 12 week follow up was undertaken to see if these effects were maintained following the intervention. This study builds on the effects of an acute stretching intervention as demonstrated in Study 1. Study Design: A randomised control trial design was used. Participants: Forty three subjects (24 OA and 19 non OA) were recruited from the local population (mean age 68.8 yrs SD: 5.0, mass 79.5 kg, SD: 14.6, height 166 cm, SD 9.8). Subjects were randomly allocated by condition to either a stretch group or a control group. Methods: Hamstring extensibility was assessed by a passive knee extension test using a Kincom® isokinetic dynamometer at baseline, following the intervention and at a 12 week follow-up. Subjects in the intervention groups stretched the main lower limb muscles 3 x 60 seconds, 5 days a week for 6 weeks. The control groups did not stretch but received a placebo intervention of interferential current. The variables of interest were maximal knee extension, peak passive torque and stiffness. The following outcome measures were also used to assess activity levels: the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Lower Limb Task Questionnaire (LLTQ) and the Aggregated Locomotor Functional (ALF) score. Analysis: A 3-factor (group x condition x time) repeated measures ANOVA model was utilised. The alpha level was set at 0.05. Results: There was a significant main effect for time and a significant interaction effect for group (stretch and control) by time for knee extension ROM, peak passive torque and stiffness (p<0.05). There was no significant interaction for condition (OA vs non OA) (p>0.05). Subjects in the stretch group had 68.9 (SD: 15.5) degrees of knee extension before the intervention and this increased significantly to 76.8 (SD: 14.4) degrees after the intervention (p<0.05). At the 12 week follow up assessment, subjects had a mean of 72.5 (SD: 20.51) degrees. This difference was not significant when compared to the post intervention assessment (p>0.05). Subjects in the control group were not significantly different for knee extension ROM following the intervention or at the 12 week follow up (p>0.05). For the knee extension ROM at 50% of the maximum torque level, there was a significant main effect for time (p<0.05) but no significant interaction effect between groups across time (p >0.05). The mean knee extension ROM recorded at 50% of the peak torque level for the stretch group pre intervention was 55.9 (SD: 15.0) degrees and this decreased significantly to 50.8 (SD 12.3) degrees post intervention (p<0.05). The mean knee extension ROM recorded at 50% of the peak torque level pre intervention for the control group was 60.2 (SD: 11.4) degrees and this decreased significantly to 57.1 (SD 11.0) degrees post intervention (p<0.05). With respect to peak passive torque subjects in the stretch group were 13.2 (SD: 7.7) Nm before the intervention and increased significantly to 19.7 (SD: 9.5) Nm after the intervention (p<0.05). At the 12 week follow up assessment, the subjects in the stretch group generated a mean peak torque of 20.2 (SD: 11.5) Nm. This difference was not significant when compared to the post intervention assessment (p>0.05). With respect to stiffness, subjects in the stretch group were 0.62 (SD: 0.3) Nm/deg before the intervention and this increased significantly to 0.84 (SD: 0.3) Nm/deg after the intervention (p<0.05). At the 12 week follow up time point, the subjects in the stretch group had a mean stiffness of 0.88 (SD: 11.5) Nm/deg. This increase was not significant when compared to the post intervention assessment (p>0.05). Subjects in the control group were not significantly different for peak passive torque or stiffness following the intervention or at the 12 week follow up. There was no significant difference for time or condition for the WOMAC or LLTQ scores. There was a significant main effect for time for both groups for the ALF score (p<0.05), however there was no significant interaction for time by condition (p>0.05). Subjects in the stretch group had a mean ALF score of 23.1 (SD: 3.9) seconds pre intervention and this reduced significantly to 19.8 (SD: 5.4) seconds post intervention (p<0.05). Subjects in the control group had a mean AFL score of 24.8 (SD: 3.1) seconds pre intervention and this reduced significantly to 22.3 (SD: 3.0) seconds post intervention (p<0.05). Conclusions: The study demonstrated that knee extension range of motion, peak passive torque and stiffness increased in those subjects who undertook the six week stretching programme. Knee extension ROM was not maintained at the 12 week follow up assessment, however peak passive torque and stiffness were. These results indicate that both elderly subjects and those with degenerative joint disease are able to demonstrate long term adaptations with periodic stretching interventions. Functional improvements were also observed following the intervention in the stretch groups and the control groups. As previous studies investigating exercise interventions in subjects with OA of the knee joint have combined stretching and strengthening exercises, this study has provided a clear picture of the effects of stretching alone in this population. However, to gain a more obvious change in function in subjects with OA of the knee joint, the combination of stretching with other exercises such as strengthening, may be required in future studies.

This thesis systematically investigates the properties of the aluminium adherend which influence the fracture toughness of aluminium-epoxy adhesive joints in humid environments. The fracture energy of the adhesive joint exposed to a humid environment in comparison with the fracture energy in a dry environment provides a measure of the joint durability. A 500C and 95% relative humidity environment is used to simulate aging of an adhesive joint over several years under normal service conditions. Initially, surface roughness is found to have a significant influence on the fracture toughness of the adhesive joint in humid conditions. A direct correlation between the bond durability and the angle of deliberately machined micro-roughness in the aluminium surface is determined. Consequently a model is developed which initially has the capacity to describe the bond durability performance. The preparation of aluminium surfaces involves the use of a novel ultramilling tool to produce well defined and controlled surface topography. This work represents the first time surface angles of features in the 1????m to 10????m range have been systematically varied and a direct relationship with bond durability has been determined. The use of surface analytical tools aids in elucidating mechanisms involved in the failure of the adhesive joint and contributes to the development of the stress based diffusion model. Examination of the aluminium oxide hydration level reveals this property has a negligible effect on the fracture toughness of the aluminium-epoxy joints exposed to humid environments. This information confirms the dominant role of the physical properties of the aluminium surface in determining the adhesive joint durability. This is the first occasion that planer oxide films grown in an RF plasma have had their hydration state adjusted in a controlled manner and their properties subsequently assessed in terms of bond durability properties. Further alteration of the aluminium surface chemistry is achieved through the application of an organo-silane coupling agent and a series of novel organo-phosphonate compounds. This work further develops the stress based diffusion model developed in conjunction with the micro-machining studies. The components of surface roughness and the ability of interfacial bonds to co-operatively share load are essential for the maintenance of fracture toughness of adhesive joints exposed to humid conditions. The ability of the silane coupling agent to share load through a chemically cross-linked film is a significant property which provides the superior fracture toughness in comparison with the phosphonate treated joints. Although the organo-phosphonate treated aluminium provides hydrolytically more stable bonds than the silane coupling agent, the film is not cross-linked via primary chemical bonds and the reduced load sharing capacity of interfacial bonds increases the bond degradation rate. The stress based diffusion model evolving from the initial work in the thesis can be used to predict the performance of more complex systems based on a thorough characterisation of the aluminium surface chemistry and topography. The stress based diffusion model essentially describes the concept of the production of micro-cavities at the epoxy-aluminium interface under mode 1 load, as a result of the distribution of strong and weak adhesive bonds. Alternatively, micro-cavities may result from an inhomogeneous stress distribution. In areas where the adhesive bonds are weak, or the local stresses are high, the interfacial load produces larger micro-cavities which provide a path of low resistance for water to diffuse along the bond-line. The water then degrades the adhesive bond either through the displacement of interfacial epoxy bonds or the hydration of the oxide to form a weak barrier layer through which fracture can occur. Alternatively, the water can hydrolyse the adhesive in the interfacial region, leading to cohesive failure of the epoxy resin. The bond durability performance of a series of complex hydrated oxide films used to pre-treat the aluminium adherend provides support for the stress based diffusion model. Whilst surface area is an important property of the aluminium adherend in producing durable bonding, the best durability achievable, between an epoxy adhesive and aluminium substrate, requires a component of surface roughness which enhances the load sharing capability in the interfacial bonding region. This component of durability performance is predicted by the model. In more specific terms, a boiling water treatment of the aluminium adherend indicates a direct correlation between bond durability, surface area and topography. The characterisation of film properties indicates that the film chemistry does not change as a function of treatment conditions, however, the film topography and surface area does. The overall bond durability performance is linked to both of these properties. The detailed examination of the hydrated oxide film, produced by the boiling water treatment of aluminium, is the first time the bond durability performance has been related to the film topography. It is also the first occasion that the mechanism of film growth has been examined over such a large treatment time. The combination of surface analysis and bond durability measurements is invaluable in confirming the properties, predicted by the stress based diffusion model, which are responsible in forming fracture resistant adhesive bonds in humid conditions. The bond durability of high surface area and low surface area hydrated oxide films indicates that surface area is an important property. However, this study confirms that the absence of the preferred surface topography limits the ultimate bond durability performance attainable. The fracture toughness measurements performed on aluminium adherends pre-treated with a low surface area film also supports the mechanism of load sharing of interfacial adhesive bonds and its contribution to the overall bond durability. The role performed by the individual molecules and particles in an oxide film is similar to the load sharing performed by the silane coupling agent molecules. Further support for the stress based diffusion model is provided by films produced on aluminium immersed in nickel salt solutions. The topography of these film alters as a function of treatment time and this is directly related to fracture toughness in humid environments. This work provides the first instance where such films have been characterised in detail and their properties related to bond durability performance. The study is also the first time that the growth mechanism of the film produced on the aluminium substrate has been examined in detail. The film growth mechanism supports the film growth model proposed for the hydrated oxide film produced by the boiling water treatment. The major findings presented in this thesis are summarised as the direct correlation between surface profile angle, the importance of co-operative load sharing of interfacial adhesive bonds and the relative insignificance of surface oxide hydration in the formation of durable aluminium-epoxy adhesion. This information is used to develop a stress based diffusion model which has the capacity to describe the fracture toughness of a range of aluminium-epoxy adhesive joint systems in humid environments. The stress based diffusion model is also capable of predicting the relative performance of the bond systems examined in the final chapters of the thesis, where complex interfacial oxide films are involved in the formation of adhesive bonds.

Passive knee motion is guided by the interaction of the articular surfaces and the restraining role of the soft-tissue structures. It is defined by characteristic kinematics within an envelope of motion. The main goal of this thesis was to simulate this characteristic motion by developing a subject-specific anatomically based finite element model. CT and MR image stacks were used to develop the geometry model and experimental (mechanical) test data was used as model input. Passive knee flexion was simulated and translational and rotational motion described using the Joint Coordinate System (JCS). The model was validated using clinical flexion and AP drawer tests. An ACL reconstruction model was also developed. Highest AP laxity was found at 30?? of flexion when the graft was positioned in the original native ACL insertion point. ACL tunnel positions were simulated according to surgical techniques. For this case, the highest AP laxity was displayed at 0?? of flexion. Four different graft materials were examined, with the quadriceps tendon graft exhibiting highest laxity, followed by the patellar tendon, braided hamstring and finally unbraided hamstring graft. The effect of malpositioning the graft's femoral attachment point from its central location was also investigated. The proximal femoral attachment point most closely mimicked the central attachment point in terms of AP laxity in the native ACL insertion group. In the ACL tunnel group, the posterior femoral attachment point most closely mimicked the intact knee. In this thesis it was found that changing the femoral insertion point of the graft can highly influence the AP laxity behaviour. Also using the surgical technique to create ACL tunnels may not necessarily produce the same kinematic behaviour as the intact knee. Lastly, this thesis has shown the importance of explicitly defining the local reference coordinate system when describing knee kinematics. Changing the coordinate system markedly alters the calculated kinematics. Ideally, a standardisation of local coordinate systems, similar to the JCS, would be proposed within the biomechanics community.

Attempts to understand the effects of ageing on the condition of a synovial joint. Knee joints of individuals with no known history of joint disease were examined and the pattern of cartilage damage was mapped macroscopically in a manner that allowed quantitation of the affected areas. / Bibliography: leaves 267-277. / vi, 277 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Pathology, 1993

Bibliography: leaves 240-257. / xvii, 274 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The main objective of this research is to develop a fundamentally new fatigue design and assessment procedure which can be used to predict the variation in crack size, strength and inspection periods as well as endurances. Basic fracture mechanics and fatigue procedures are used to illustrate this new technique. / Thesis (Ph.D.)--University of Adelaide, Depts. of Civil & Environmental Engineering and Mechanical Engineering, 1997?

The purpose of this study was to characterize glenohumeral joint laxity and stiffness using instrumented arthrometry. To evaluate the validity of an instrumented measurement system we compared cutaneous and bone-pinned measures of laxity and stiffness that replicate previously reported in vivo methodology. Characterization of capsular laxity was achieved through determination of the sagittal plane translational area at increasing levels of quantified force. Finally, a method for increasing the objectivity of the standard manual laxity examination was developed for the orthopaedic clinician to quantify humeral head translation and capsular volume in vivo. We hypothesized that: 1) cutaneous measures could accurately predict bone-pinned measures, 2) capsular laxity would increase with increasing levels of applied force, and 3) manual cutaneous, manual bone-pinned, and force-displacement bone-pinned measures of translation would be equal. Thirty fresh frozen cadaveric shoulder specimens (mean age=70��14 years) were tested. The shoulders were thawed and mounted to a custom-made shoulder-testing apparatus. Displacement was measured using an electromagnetic tracking system. Sensors were secured cutaneously and with bone-pins to the scapula and humerus. Force-displacement testing was performed using a load applicator and manual displacement testing utilized the anterior/posterior drawer and inferior sulcus tests. A comparison of cutaneous and bone-pinned measures of laxity and stiffness revealed good to excellent criterion validity (r=0.68 to 0.79). Examination of displacement measures at increasing levels of force revealed increasing capsular laxity with symmetric directional compliance. No significant difference was observed between anterior and posterior translation (0.4 mm, p=.55), with significant differences between inferior and anterior (4.6 mm, p<.0001) and between inferior and posterior (5.1 mm, p<.0001). A comparison of manual cutaneous to bone-pinned manual and kinetic measures of translation revealed a significant difference between methods (p=.0024) and between directions (p<.0001) with no significant interaction (p=.0948). Estimations of the force required to achieve clinical end-point suggest that greater force is required in the anterior (173 N) direction compared to posterior (123 N) and inferior (121 N). We have developed two new methods to measure glenohumeral joint kinematics and reported new information regarding normal kinematics of the glenohumeral joint. / Graduation date: 2001