Esta pesquisa apresenta os resultados obtidos em análise laboratorial de misturas asfálticas de módulo elevado para aplicação em camada de base de pavimento. Historicamente, pode-se dizer que este tipo de mistura asfáltica em camadas de base resulta em melhor comportamento mecânico comparado com o de misturas asfálticas usinadas com CAP convencional. As misturas de módulo elevado apresentam vantagens em relação às convencionais com maior resistência à deformação permanente e maior vida de fadiga. Inicialmente, foram realizados ensaios laboratoriais de caracterização dos agregados e de três tipos de ligantes asfálticos: CAP A e CAP B, ambos ligantes duros com penetração entre 10 e 20dmm, e um CAP convencional, CAP 30/45. Foram dosadas três misturas asfálticas, com uma graduação preestabelecida, e com os três ligantes asfálticos estudados, pelos métodos Marshall e SUPERPAVE. Os teores de projeto pelo método Marshall foram de 0,2 a 0,3% superiores ao calculado pelo SUPERPAVE. Verificou-se o atendimento das especificações francesas quanto ao volume de vazios das misturas compactadas com os CAPs A e B pelo compactador giratório francês PCG). Foram determinados os danos por umidade induzida, tendo sido verificado que a mistura com CAP B requer um melhorador de adesividade. Determinaram-se os afundamentos por deformação permanente, as resistências à tração, os módulos de resiliência em dois equipamentos diferentes (MTS e UTM), os módulos dinâmicos, e a vida de fadiga por compressão diametral e por flexão em viga de 4 pontos, das três misturas asfálticas estudadas. As deformações permanentes para as misturas com CAP A e CAP B são menores que o limite máximo estabelecido pelas diretrizes europeias, e inferiores ao valor obtido com o mistura com CAP 30/45. Os módulos de resiliência mostraram rigidez distinta entre as misturas do módulo elevado, sendo que a mistura com CAP B é duas vezes mais rígida que a mistura com CAP A, que por sua vez é similar ao módulo com CAP 30/45. Obtiveram-se resultados similares de módulo de resiliência com equipamentos distintos. Os resultados dos ensaios de módulo dinâmico demonstraram proximidade de comportamento da mistura asfáltica com CAP A com misturas asfálticas com ligantes modificados; o módulo dinâmico da mistura com CAP B é similar àquele com CAP 30/45. Os resultados dos dois ensaios de fadiga empregados neste estudo demonstraram o melhor comportamento de misturas asfálticas compostas por ligantes duros e de módulo elevado, quando comparada com a mistura convencional. Todos os resultados demonstram que há benefícios de misturas de módulo elevado como camada de base em relação às misturas com CAP convencional, e que esta é uma solução com grande potencial para estruturas de pavimento para tráfego pesado. / This study presents the results obtained in laboratory analysis, about high modulus asphalt mixtures for use in base layer of pavement. Historically, it can be said that this type of mixture, when use in base layer, results in better mechanical behavior when compared with conventional asphalts. High modulus mixtures provide better behavior as it related layer`s permanent deformation and a higher fatigue life. Initially, laboratory tests for characterizing aggregates and three types of asphalt binders were carried out: Binder A and Binder B, both hard binders with penetration between 10 and 20dmm, and a conventional binder, namelly 30/45. Three types of asphalt mixtures were designed, with one predefined graduation and with those three asphalt binders, using Marshall and SUPERPAVE methods. Marshall`s binder contents were from 0.2 to 0.3% higher than SUPERPAVE. The compacted asphalt mixtures were in compliance with French specifications in terms of air void content of Binder A and Binder B using the French gyratory compactor (PCG). Moisture-induced damage test was performed and it was verified that Binder B needs an antistrip agent. Rutting, indirect tensile strength, resilient modulus in two different machines (MTS and UTM), dynamic modulus, and fatigue life by diametral compression and four point bending tests, were carried out with the three asphalt mixtures studied. The results of rutting for mixtures with Binders A and B were lower than the maximum limit of European specifications, and lower than the result with Binder 30/45. Resilient modulus showed different stiffness between the high modulus mixtures, where the asphalt mixture with Binder B was twice stiffer than the mixture with Binder A, which in turn is similar to the resilient modulus of the asphalt mixtures with Binder 30/45. Analogous results were observed in different resilient modulus machines. Dynamic modulus results showed similar behavior between the asphalt mixture with Binder A and asphalt mixture with modified binders; dynamic modulus of the asphalt mixture with Binder B was similar to the asphalt mixture with Binder 30/45. Results in the two fatigue tests were better for the asphalt mixtures with hard binders and high modulus in comparison with the conventional asphalt mixture. All the results demonstrate benefits of high modulus mixtures as base layer in pavements in comparison with asphalt mixtures with conventional binders, and the solution has a great potential in pavement structures for heavy traffic.

Este trabalho apresenta os resultados alcançados em uma pesquisa experimental que objetivou estudar misturas asfálticas com módulos de resiliência elevados (EME), para emprego em camadas estruturais de pavimentos. As misturas EME são solução muito utilizada para pavimentos com elevado volume de tráfego, especialmente na França, por serem muito resistentes às deformações permanentes apresentando bom comportamento à fadiga. Foram caracterizados os ligantes asfálticos utilizados e as misturas projetadas. Para caracterização e verificação de desempenho, realizaram-se os ensaios da Metodologia Marshall, ensaios de resistência à tração, módulo de resiliência à compressão diâmetral, fadiga à tensão controlada, resistência ao dano por umidade induzida (Método Lottman Modificado), perda de massa por desgaste (Cântabro) e deformação permanente (creep dinâmico e simulador tipo LCPC). As misturas asfálticas projetadas apresentaram melhor desempenho mecânico em comparação com uma mistura de comparação formulada com ligante convencional (CAP 50/70). Foi construída uma pista experimental com o objetivo de verificar aspectos executivos e monitorar o desempenho da estrutura submetida a ensaios acelerados. Os danos causados pelas solicitações impostas pelo simulador de tráfego UFRGS-DAER/RS foram monitorados através de medidas de deflexões e afundamentos nas trilhas de roda e da inspeção visual para verificar a ocorrência de trincamento superficial. O carregamento aplicado superou os 200 mil ciclos, com cargas de eixo de 100 e 120 kN. O ATR médio observado no final do experimento totalizou 6 mm. Não foi observado trincamento na superfície do pavimento. A partir dos resultados obtidos é possível concluir que o emprego de misturas asfálticas de módulo elevado em camadas estruturais de pavimentos permitirá a construção de estruturas de melhor qualidade técnica, podendo contribuir para o aumento da vida útil das rodovias. / This work presents an experimental study that searched to study high modulus asphalt mixtures (EME) for structural layers of pavements. The EME is a well-known solution for high volume roads, especially in France, presenting better results in terms of rutting and fatigue cracking than conventional mixtures. Asphalt binders and designed mixtures were characterized. To evaluate the laboratorial mixes performance, Marshall Methodology, tensile strength, resilient modulus, fatigue (controlled stress mode), stripping (Modified Lottman test), weight loss (Cantabro Methodology) and permanent deformation (dynamic creep and LCPC simulator) were carried out. The results showed that the EME mixtures present better mechanical behavior than conventional asphalt mixture. An experimental section was built to verify the construction features and to monitor the progressive degradation produced by a linear traffic simulator. For the accompaniment of the degradation were monitored the pavement deflections, rutting and cracking. 200.000 load cycles were applied with axle loads of 100 and 120 kN.The rut depth in the end of experiment totalized 6 mm. Fatigue cracking was not observed in the pavement surface. The study results show that the use of EME mixtures in structural layers of pavements will allow the construction of structures with remarkably good technical quality, contributing to increase pavement life.

Este trabalho apresenta os resultados alcançados em uma pesquisa experimental que objetivou estudar misturas asfálticas com módulos de resiliência elevados (EME), para emprego em camadas estruturais de pavimentos. As misturas EME são solução muito utilizada para pavimentos com elevado volume de tráfego, especialmente na França, por serem muito resistentes às deformações permanentes apresentando bom comportamento à fadiga. Foram caracterizados os ligantes asfálticos utilizados e as misturas projetadas. Para caracterização e verificação de desempenho, realizaram-se os ensaios da Metodologia Marshall, ensaios de resistência à tração, módulo de resiliência à compressão diâmetral, fadiga à tensão controlada, resistência ao dano por umidade induzida (Método Lottman Modificado), perda de massa por desgaste (Cântabro) e deformação permanente (creep dinâmico e simulador tipo LCPC). As misturas asfálticas projetadas apresentaram melhor desempenho mecânico em comparação com uma mistura de comparação formulada com ligante convencional (CAP 50/70). Foi construída uma pista experimental com o objetivo de verificar aspectos executivos e monitorar o desempenho da estrutura submetida a ensaios acelerados. Os danos causados pelas solicitações impostas pelo simulador de tráfego UFRGS-DAER/RS foram monitorados através de medidas de deflexões e afundamentos nas trilhas de roda e da inspeção visual para verificar a ocorrência de trincamento superficial. O carregamento aplicado superou os 200 mil ciclos, com cargas de eixo de 100 e 120 kN. O ATR médio observado no final do experimento totalizou 6 mm. Não foi observado trincamento na superfície do pavimento. A partir dos resultados obtidos é possível concluir que o emprego de misturas asfálticas de módulo elevado em camadas estruturais de pavimentos permitirá a construção de estruturas de melhor qualidade técnica, podendo contribuir para o aumento da vida útil das rodovias. / This work presents an experimental study that searched to study high modulus asphalt mixtures (EME) for structural layers of pavements. The EME is a well-known solution for high volume roads, especially in France, presenting better results in terms of rutting and fatigue cracking than conventional mixtures. Asphalt binders and designed mixtures were characterized. To evaluate the laboratorial mixes performance, Marshall Methodology, tensile strength, resilient modulus, fatigue (controlled stress mode), stripping (Modified Lottman test), weight loss (Cantabro Methodology) and permanent deformation (dynamic creep and LCPC simulator) were carried out. The results showed that the EME mixtures present better mechanical behavior than conventional asphalt mixture. An experimental section was built to verify the construction features and to monitor the progressive degradation produced by a linear traffic simulator. For the accompaniment of the degradation were monitored the pavement deflections, rutting and cracking. 200.000 load cycles were applied with axle loads of 100 and 120 kN.The rut depth in the end of experiment totalized 6 mm. Fatigue cracking was not observed in the pavement surface. The study results show that the use of EME mixtures in structural layers of pavements will allow the construction of structures with remarkably good technical quality, contributing to increase pavement life.

Esta pesquisa apresenta os resultados obtidos em análise laboratorial de misturas asfálticas de módulo elevado para aplicação em camada de base de pavimento. Historicamente, pode-se dizer que este tipo de mistura asfáltica em camadas de base resulta em melhor comportamento mecânico comparado com o de misturas asfálticas usinadas com CAP convencional. As misturas de módulo elevado apresentam vantagens em relação às convencionais com maior resistência à deformação permanente e maior vida de fadiga. Inicialmente, foram realizados ensaios laboratoriais de caracterização dos agregados e de três tipos de ligantes asfálticos: CAP A e CAP B, ambos ligantes duros com penetração entre 10 e 20dmm, e um CAP convencional, CAP 30/45. Foram dosadas três misturas asfálticas, com uma graduação preestabelecida, e com os três ligantes asfálticos estudados, pelos métodos Marshall e SUPERPAVE. Os teores de projeto pelo método Marshall foram de 0,2 a 0,3% superiores ao calculado pelo SUPERPAVE. Verificou-se o atendimento das especificações francesas quanto ao volume de vazios das misturas compactadas com os CAPs A e B pelo compactador giratório francês PCG). Foram determinados os danos por umidade induzida, tendo sido verificado que a mistura com CAP B requer um melhorador de adesividade. Determinaram-se os afundamentos por deformação permanente, as resistências à tração, os módulos de resiliência em dois equipamentos diferentes (MTS e UTM), os módulos dinâmicos, e a vida de fadiga por compressão diametral e por flexão em viga de 4 pontos, das três misturas asfálticas estudadas. As deformações permanentes para as misturas com CAP A e CAP B são menores que o limite máximo estabelecido pelas diretrizes europeias, e inferiores ao valor obtido com o mistura com CAP 30/45. Os módulos de resiliência mostraram rigidez distinta entre as misturas do módulo elevado, sendo que a mistura com CAP B é duas vezes mais rígida que a mistura com CAP A, que por sua vez é similar ao módulo com CAP 30/45. Obtiveram-se resultados similares de módulo de resiliência com equipamentos distintos. Os resultados dos ensaios de módulo dinâmico demonstraram proximidade de comportamento da mistura asfáltica com CAP A com misturas asfálticas com ligantes modificados; o módulo dinâmico da mistura com CAP B é similar àquele com CAP 30/45. Os resultados dos dois ensaios de fadiga empregados neste estudo demonstraram o melhor comportamento de misturas asfálticas compostas por ligantes duros e de módulo elevado, quando comparada com a mistura convencional. Todos os resultados demonstram que há benefícios de misturas de módulo elevado como camada de base em relação às misturas com CAP convencional, e que esta é uma solução com grande potencial para estruturas de pavimento para tráfego pesado. / This study presents the results obtained in laboratory analysis, about high modulus asphalt mixtures for use in base layer of pavement. Historically, it can be said that this type of mixture, when use in base layer, results in better mechanical behavior when compared with conventional asphalts. High modulus mixtures provide better behavior as it related layer`s permanent deformation and a higher fatigue life. Initially, laboratory tests for characterizing aggregates and three types of asphalt binders were carried out: Binder A and Binder B, both hard binders with penetration between 10 and 20dmm, and a conventional binder, namelly 30/45. Three types of asphalt mixtures were designed, with one predefined graduation and with those three asphalt binders, using Marshall and SUPERPAVE methods. Marshall`s binder contents were from 0.2 to 0.3% higher than SUPERPAVE. The compacted asphalt mixtures were in compliance with French specifications in terms of air void content of Binder A and Binder B using the French gyratory compactor (PCG). Moisture-induced damage test was performed and it was verified that Binder B needs an antistrip agent. Rutting, indirect tensile strength, resilient modulus in two different machines (MTS and UTM), dynamic modulus, and fatigue life by diametral compression and four point bending tests, were carried out with the three asphalt mixtures studied. The results of rutting for mixtures with Binders A and B were lower than the maximum limit of European specifications, and lower than the result with Binder 30/45. Resilient modulus showed different stiffness between the high modulus mixtures, where the asphalt mixture with Binder B was twice stiffer than the mixture with Binder A, which in turn is similar to the resilient modulus of the asphalt mixtures with Binder 30/45. Analogous results were observed in different resilient modulus machines. Dynamic modulus results showed similar behavior between the asphalt mixture with Binder A and asphalt mixture with modified binders; dynamic modulus of the asphalt mixture with Binder B was similar to the asphalt mixture with Binder 30/45. Results in the two fatigue tests were better for the asphalt mixtures with hard binders and high modulus in comparison with the conventional asphalt mixture. All the results demonstrate benefits of high modulus mixtures as base layer in pavements in comparison with asphalt mixtures with conventional binders, and the solution has a great potential in pavement structures for heavy traffic.

Este trabalho apresenta os resultados alcançados em uma pesquisa experimental que objetivou estudar misturas asfálticas com módulos de resiliência elevados (EME), para emprego em camadas estruturais de pavimentos. As misturas EME são solução muito utilizada para pavimentos com elevado volume de tráfego, especialmente na França, por serem muito resistentes às deformações permanentes apresentando bom comportamento à fadiga. Foram caracterizados os ligantes asfálticos utilizados e as misturas projetadas. Para caracterização e verificação de desempenho, realizaram-se os ensaios da Metodologia Marshall, ensaios de resistência à tração, módulo de resiliência à compressão diâmetral, fadiga à tensão controlada, resistência ao dano por umidade induzida (Método Lottman Modificado), perda de massa por desgaste (Cântabro) e deformação permanente (creep dinâmico e simulador tipo LCPC). As misturas asfálticas projetadas apresentaram melhor desempenho mecânico em comparação com uma mistura de comparação formulada com ligante convencional (CAP 50/70). Foi construída uma pista experimental com o objetivo de verificar aspectos executivos e monitorar o desempenho da estrutura submetida a ensaios acelerados. Os danos causados pelas solicitações impostas pelo simulador de tráfego UFRGS-DAER/RS foram monitorados através de medidas de deflexões e afundamentos nas trilhas de roda e da inspeção visual para verificar a ocorrência de trincamento superficial. O carregamento aplicado superou os 200 mil ciclos, com cargas de eixo de 100 e 120 kN. O ATR médio observado no final do experimento totalizou 6 mm. Não foi observado trincamento na superfície do pavimento. A partir dos resultados obtidos é possível concluir que o emprego de misturas asfálticas de módulo elevado em camadas estruturais de pavimentos permitirá a construção de estruturas de melhor qualidade técnica, podendo contribuir para o aumento da vida útil das rodovias. / This work presents an experimental study that searched to study high modulus asphalt mixtures (EME) for structural layers of pavements. The EME is a well-known solution for high volume roads, especially in France, presenting better results in terms of rutting and fatigue cracking than conventional mixtures. Asphalt binders and designed mixtures were characterized. To evaluate the laboratorial mixes performance, Marshall Methodology, tensile strength, resilient modulus, fatigue (controlled stress mode), stripping (Modified Lottman test), weight loss (Cantabro Methodology) and permanent deformation (dynamic creep and LCPC simulator) were carried out. The results showed that the EME mixtures present better mechanical behavior than conventional asphalt mixture. An experimental section was built to verify the construction features and to monitor the progressive degradation produced by a linear traffic simulator. For the accompaniment of the degradation were monitored the pavement deflections, rutting and cracking. 200.000 load cycles were applied with axle loads of 100 and 120 kN.The rut depth in the end of experiment totalized 6 mm. Fatigue cracking was not observed in the pavement surface. The study results show that the use of EME mixtures in structural layers of pavements will allow the construction of structures with remarkably good technical quality, contributing to increase pavement life.

Biodegradable thermoplastic composites were prepared using high modulus lyocell fibers and cellulose acetate butyrate (CAB). Two reinforcement fiber types: fabric and continuous fiber tow were used. Fabric had advantages of uniform alignment and easier processing, but lacked the use as a unidirectional reinforcement and a continuous method of matrix application. Three different matrix application methods were screened for both fiber types. Matrix application by suspension of particles in water was not feasible because of particle sizes > 15 &micro m. The other disadvantages were high moisture absorption during matrix application and void formation during consolidation. Melt processing technique using alternating sandwich structure of fabrics and CAB films produced composites with impressive appearance, low void contents and low moisture absorption. However, SEM results revealed interfacial failure and extensive fiber pull out. Relatively larger fiber and matrix regions were present on the scale of 10^-3m. Solution prepregging technique using methyl ethyl ketone (MEK) as a solvent for CAB and continuous fibers as reinforcement produced composites with uniform matrix distribution, high tensile strengths and high modulus, and even wetting of fibers by CAB. A maximum tensile modulus of 21.5 GPa and a maximum strength of 251.7 MPa were achieved for a continuous fiber reinforced composites at a volume fraction of 66.5% compared to 0.8 GPa and 76 MPa for the matrix, respectively. Void contents and water absorption were relatively high compared to comparable carbon fiber composites. / Master of Science

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The development of light and sti aerospace structural panels is very important in the aerospace industry, e.g. a lighter satellite requires less fuel to launch it into space which in turn saves money for the owner of the satellite. This thesis describes the design, optimisation, manufacturing and testing of a ribbed light alloy core - carbon bre face sheets, sandwich-type, satellite panel operating at launch loading conditions (115 m/s2 accelerations and requiring a minimum structural natural frequency of 90 Hz) to determine the optimum sti ness per mass ratio of the panel. The panel layout was based on a satellite panel designed by SunSpace and Information Systems for the Sumbandila satellite. Only the black box mounting positions of the original panel were used in the optimisation of the new panel. The core of the evaluation panel was manufactured from aluminium (6082-T6). The carbon bre skins were manufactured from unidirectional high modulus carbon bre (K63712) in a [0/90/0] wet layup with the 0± direction in the longitudinal direction of the panel. A three-dimensional model of the panel consisting of 3D wedge elements and containing all the boundary conditions was modelled with the use of the nite element software MSC Patran. The model was optimised with the use of optimisation software Genesis to locate the rib positions. Genesis removes all the elements containing the least amount of stress; only 30% of the core elements were kept while restricting the elements to form an extruded con guration (for milling machining) throughout the thickness of the panel. The rib elements remaining were replaced in MSC Patran by shell elements and the shell element thicknesses were optimised with the use of Genesis to ensure the lightest and sti est possible structure. The optimised rib thicknesses were imported into MSC Patran and the numerically optimised model could then be analysed with MSC Nastran. The numerical model was converted into a manufacturable structure and the core was machined from a solid aluminium sheet. The ribs were machined in the shape of an Ibeam to allow for minimum weight and a su cient bonding area for the two carbon bre face sheets. Elevated circular surfaces, protruding through the carbon bre sheets, were machined in the position of the black box mountings to allow for better heat transfer away from the black boxes. The carbon bre face sheets were bonded to the metal core (3M Scotch-Weld 9323 B/A). The nished panel was put through various tests to determine whether it is suitable for use in the aviation industry. The tests included modal testing, random vibration testing and temperature testing to determine if the structure is durable enough for use in satellites. The test results are promising and show that a substantive amount of money can be saved by reducing the mass on the structure. By using optimisation software and ribbed light alloy - carbon bre face sheets sandwich structures the performance of the structures can be improved without adding mass to the structure. / AFRIKAANSE OPSOMMING: Die ontwikkeling van ligter en stywer lugvaartstruktuur panele is baie belangrik in die lugvaart-industrie, bv. 'n ligter satelliet benodig minder brandstof om tot in 'n wentelbaan lanseer te word. Dit bespaar sodoende lanseerkostes vir die eienaar van die satelliet. In die verslag word die ontwerp, optimering, vervaardiging en toets van 'n gewebde, ligte allooi kern - koolstofveselvel, saamgestelde materiaal, satelliet struktuurpaneel wat onderwerp word aan lanseer belastingstoestande van ongeveer 115 m/s2 versnellings ondersoek. Die tegnieke word gebruik om die optimale styfheid per eenheidsmassa-verhouding te bepaal. Die paneel benodig 'n minimum strukturele eerste natuurlike frekwensie van 90 Hz. Die basiese paneel uitleg is verkry vanaf 'n satellietpaneel wat deur SunSpace and Information Systems ontwerp is vir die basisplaat van die Sumbandila satelliet. Die enigste geometrie wat van die oorspronklike struktuur behou is om die nuwe struktuur te optimeer is die vashegtingspunt-posisies van die swart-kassies. Die kern van die ge-optimeerde struktuur is vervaardig uit gemasjieneerde aluminium (6082-T6). Die koolstofvesel-velle is vervaardig uit enkelrigting hoë-modulus koolstofvesel-doek (K63712). Die oplegging is gedoen met 'n nat-opleggingsproses waar die drie lae van elke vel 'n [0/90/0] oriëntasie het met, die 0± lae in die langsrigting van die paneel. 'n Drie-dimensionele eindige element model van die paneel is geskep met behulp van die MSC Patran sagteware pakket met die model hoofsaaklik opgebou uit 3D wig-elemente. Al die lanseertuig vashegtingsrandwaardes is in die eindige element model ingebou. Om die web posisies te bepaal is die Genesis optimeringsagteware pakket gebruik. Verskeie ontwerpsvoorwaardes is gespesi seer waaraan die optimeringsproses moes voldoen. Slegs 30% van die wig-elemente mag behoue bly in die optimeringsproses en al die elemente deur die dikte van die paneel moet of behou of verwyder word. Dit verseker dat die resultaat masjieneerbaar is met 'n freesmasjien. Die oorblywende wig-elemente is in MSC Patran vervang met dop-elemente. Die dopelemente se diktes is ge-optimeer met Genesis om die ligste en styfste struktuur moontlik te kry. Die ge-optimeerde dop-element diktes is in die MSC Patran model ingetrek. Die numeries ge-optimeerde model is daarna met behulp van MSC Nastran ge-analiseer. Nadat die numeriese model omgeskakel is in 'n vervaardigbare struktuur is die kern gemasjieneer uit 'n soliede blok aluminium. Die webbe is ontwerp en vervaardig in 'n I-balk vorm. Dit laat toe dat die webbe 'n minimum gewig en genoegsame area het waarop die koolstofvesel velle geheg kan word. Verhewe vlakke is gemasjieneer op die aluminium kern in die posisies van die swart-kassie vashegtingpunte. Hierdie verhewe vlakke steek deur die koolstofvesel-vel aan die kant waar die swart-kassies vasgeheg word. Dit verseker 'n metaal-op-metaal verbinding tussen die kern en die swart-kassies vir beter hittegeleiding. 3M Scotch-Weld 9323 B/A epoksie is gebruik om die koolstofvesel-velle aan die aluminium kern te heg. Die voltooide struktuur is aan 'n reeks toetse onderwerp om te bepaal of dit geskik is om in die ruimtevaart-industrie gebruik te kan word. Dit sluit modale toetse, lukrake vibrasie toetse en temperatuursverandering toetse in. Die toetsresultate sal bepaal of die struktuur duursaam genoeg is om in satelliete gebruik te word. Die toetsresultate is belowend en dui daarop dat deur massa te bespaar op die struktuur, 'n aansienlike bedrag op satelliet lanseer-kostes bespaar kan word. Deur optimeringsagteware tesame met gewebde ligte allooi kern - koolstofvesel vel, saamgestelde materiaal strukture te gebruik kan die werksverrigting van die strukture verbeter sonder dat massa bygevoeg word.

Fibre reinforced composites have higher specific strength and stiffness in comparison to metals. However, composites are susceptible to impact damage resulting in degradation of mechanical properties especially compression strength. Numerous studies have been conducted to improve the impact damage tolerance of composite laminates using modified resin systems, thermoplastic matrices, 3-D fibre architectures and through thickness reinforcement. This work is primarily focussed on incorporating non dissolvable polypropylene fibres (PP) in a thermoset matrix for improving the damage tolerance. Commingling and wrapping techniques have been investigated. PP fibres have been incorporated at the preform stage and hence do not adversely affect the viscosity of the resin during infusion. The healing effect of PP fibres on impact damaged composite laminates when heating is introduced has also been studied. High velocity impact test results showed that using commingled glass/PP fibres increased the total energy absorption of composite laminates by 20% due to the extensive plastic deformation of the PP fibres and through the use of toughening mechanisms in the form of resin cracking and delamination. It has been found that PP fibres provide protection to the glass fibres during low velocity impact loading, so fewer fibre breakages occur which lead to improved residual properties compared with pristine glass laminates. Compression after impact (CAI) tests showed that the residual strength as a percentage of non-impacted strength increased with percentage of PP fibres used. For impact of 20-50J, glass/epoxy laminates retained 32 45% of their compressive strength while laminates with 7%, 13% and 18% PP fibres retained 37 50%, 42-52% and 43-60% of their compressive strength, respectively. It was also observed that glass/PP woven laminates had better compressive strength retention (62 83%) than the glass/PP non-crimp laminates (37-50%). Composite laminates with high-modulus PP fibres (Innegra) exhibited higher residual compression strengths in comparison to laminates with lower modulus PP fibres. For 15-50J impact, glass/Innegra laminates showed residual compression strength of 50 63% in comparison to 39-60%; laminates without thermoplastic fibres exhibited 33 43% residual compression strength. Modulus of thermoplastic fibres appears to be important at higher energy levels. Healing of damaged commingled laminates produced a significant reduction in the damage area and a corresponding increase in CAI strength after heating at 200ºC; CAI strength of healed laminates is about 85% of undamaged samples in comparison to 60% for non-healed samples. A novel micro-wrapping technique, developed in this work, demonstrated significant reduction in damage area (46%) in comparison to the commingling method. Core wrapped laminates had higher residual strength (43-60%) than glass laminates (33-43%). Better PP distribution in core-wrapped composites helped to decrease the PP rich areas and the impact damage did not propagate easily in comparison to commingled composites. However due to the reduction in damage area, impact energy absorption in core wrapped laminates was lower than for commingled.

Der derzeitige technische Fortschritt stützt sich maßgeblich auf die Nutzung von elektrischem Strom. Der Anteil der Stromerzeugung aus Sonnenlicht hat mittlerweile in Deutschland den der Wasserkraft überschritten, der 1990 noch der größte regenerative Energielieferant war. Die Technologie der Photovoltaik (PV) wandelt die hochenergetische Strahlung der Sonne in elektrischen Strom um und nutzt dabei häufig Glasplatten als tragende Struktur. Der Hauptanspruch dieser Arbeit liegt in der Entwicklung und Untersuchung eines Befestigungssystems mit einer höher- oder hochmoduligen Klebverbindung zum gläsernen PV-Modul sowie einer möglichst universell einsetzbaren Fügeverbindung zur Unterkonstrukion. Die systematische Enwicklung der Fügeverbindung zum PV-Modul basiert auf dem Ansatz eines flexiblen, stützenden \\hbox{Ringes} für das Fügeelement (Halter), um die durch eine mechanische Belastung der Module induzierten Zugspannungen im Glas über der Fügeelementkante zu reduzieren. Eine neuartige, kombinierte Klammer-Keil-Verbindung sichert die Befestigung auf einer von ihr unabhängigen Unterkonstruktion sowohl quer als auch längs zur Schienenrichtung. Experimentelle Arbeiten charakterisieren die eingesetzte Klebverbindung unter verschiedenen Beanspruchungsszenarien, um sowohl konstruktions- als auch klebstoffbedingte Möglichkeiten und Grenzen der Fügeverbindung für die vorliegende Anwendung zu identifizieren. Die Untersuchungen weisen zudem geeignete Vorbehandlungsmaßnahmen der Aluminiumoberflächen aus. Sowohl numerische Simulationen als auch die neuartig eingesetzte Nahbereichsphotogrammetrie bestätigen in Bauteiluntersuchungen die vorteilige Wirkung des flexiblen, höhermodulig geklebten Ringes. Die vorliegende Arbeit setzt sich hierbei auch kritisch mit unterschiedlichen Einflüssen auf die Ergebnisse auseinander, die einerseits durch verschiedene Prüfstände hervorgerufen werden können und andererseits auch den verwendeten Methoden zugrunde liegen. / Today much of technical advances are due to the usage of electricity. The contribution of solar power to the production of electricity in Germany currently surpasses water powered electricity which was in 1990 the almost exclusive renewable energy source. The technology of photovoltaic systems based on high-powered sun radiation, often utilizes glass plates as a supporting structure. This dissertation primarily focuses on the research and development of a mounting system with a higher or high modulus adhesively bonded joint to the PV-module as well as an all-purpose connection to the substructure. The systematical development process of the connection to the PV-module is based on the approach of a flexible supporting ring-shaped mounting element. This reduces the tension within the glass surface at the edge of the mounting element when mechanically loading the PV-module. A novel connection using a clamp-wedge combination ensures the ability to mount the PV-module horizontally or vertically to the rail substructure. Through the development process, the bonded joint is exposed to various scenarios where the construction as well as the adhesive possibilities and limitations under each scenario are analyzed. Research outcomes yield recommendations for appropriate pre-treatment of the aluminum surfaces. Numerical simulations as well as the novel use of the near-field photogrammetry method confirmed beneficial action of the flexible ring-shaped mounting element within assembly testing of large glass specimens. This dissertation discusses how different variables can have a considerable effect on results when introduced through the testing device and through monitoring methods.

Le but de ce travail est d’étudier le potentiel d’un bitume naturel (BN) extrait en Albanie pour la production des bitumes durs (BD) et des enrobés à module élevé (EME). Pour la production des BD, différentes techniques de raffinage du pétrole existent. Néanmoins, avec certains bruts pétroliers il est impossible de les fabriquer. De plus, les BD de raffinerie comportent souvent des défauts qui limitent leurs applications. Ces raisons, couplées à des questions d’approvisionnement, conduisent à chercher des méthodes de substitution. Dans ce contexte, il est intéressant d’utiliser des BN. Cette étude a montré que le BN d’Albanie donne des BD et des EME en conformité avec la Normalisation Européenne, résistants au vieillissement et performants aux basses températures. Un dosage adéquat permet de formuler des matériaux d’une dureté désirée en réponse des exigences techniques des applications routières visées tout en facilitant la gestion des stocks de bitumes dans les centrales d’enrobages. / The aim of this thesis is to study the potential of a natural bitumen (NB) mined in Albania in the production of hard bitumens (HB) and that of high modulus asphalt concrete (HMAC). Various petroleum refining techniques are available for the production of HB. Nevertheless, this is impossible with some crude oils. In addition, HB from refineries often present shortcomings which limit their applications. These reasons, coupled with practical issues related to HB supply, motivate the research of alternative methods. In this industrial context it is interesting to use NB. This study has shown that the Albanian NB provides HB and HMAC in accordance with European Standards, resistant to aging and relatively performant at low temperatures. The proper dosage of this NB allows the formulation of materials of desired properties, in response to the technical requirements of the considered road applications, facilitating in this way the use of bitumen stocks in asphalt concrete production plants.