Aplicações dos laminados híbridos metal-fibra incluem, além da indústria aeronáutica, as indústrias naval e automobilística. Diferentemente do setor aeronáutico, pesquisas sobre impactos mecânicos nas duas outras áreas da mobilidade são freqüentemente limitadas pela disponibilidade de equipamentos laboratoriais, de modo que é desejável o desenvolvimento de procedimentos de baixo custo para a determinação da resistência e tolerância a danos por impacto dos materiais de construção. Neste trabalho, a resistência a danos por impacto transversal do laminado híbrido metal-fibra Glare-5® foi determinada via três diferentes metodologias. A primeira utiliza um aparato sofisticado aparato Laser-Doppler para monitorar a aceleração e desaceleração de um impactador esférico de aço com 5 mm de diâmetro durante o evento do choque mecânico. O segundo método se baseia apenas nos valores de carga (força aplicada) vs. o tempo de impacto para a obtenção da energia absorvida pelo material. O terceiro considera somente os dados da velocidade do impactador, ou projétil, imediatamente antes e após o impacto. Concluiu-se que os valores de energia obtidos segundo as duas primeiras metodologias são similares, com o Laser-Doppler gerando resultados levemente não-conservadores, comprovando assim a possibilidade da derivação da resistência ao impacto do laminado através de um experimento simples e rápido, que utiliza apenas uma célula de carga digital para a monitoração da força aplicada em função do tempo. O terceiro método apresentou resultados substancialmente superiores às duas primeiras metodologias, sendo classificado como inadequado aos propósitos do projeto. Determinou-se que o laminado híbrido Glare-5®; absorve entre 60% e 80% da energia disponibilizada em impactos ditos leves, no intervalo de 1 a 6 Joules. Por fim, comprovou-se que a rigidez do material (módulo de elasticidade) é a propriedade residual (numa base de tolerância a danos) mais clara e consistentemente degradada pelo impacto previamente aplicado ao material. / Applications of hybrid fiber-metal laminates include, besides aeronautical industry, the automotive and naval industries. Unlike aeronautical field, impact research activities in the former areas of mobility industry are frequently limited by available laboratory equipment, so that it would be desirable to develop low-cost procedures to determine impact resistance and tolerance properties of construction materials. In this work, the transversal (trans-thickness) impact resistance and tolerance of hybrid fiber-metal laminate Glare-5® have been determined via three different methodologies. The first one utilizes sophisticated apparatus comprising a Laser-Doppler device to monitor deceleration/re-acceleration of 5 mm-diameter steel-ball impactor during the mechanical shock event. The second approach merely relies on the force (applied load) vs. impact time for determining the absorbed energy during the dynamic process. The third methodology requires only impactor velocity data points, immediately before and after the impact. It has been concluded that the energy values obtained from Laser- Doppler and load cell methods are very similar, with the former method producing slightly non-conservative results, allowing one to rapidly derive the impact resistance of hybrid laminate materials through very simple experimental set-ups employing digital load cells only. The third method presented somewhat higher results as compared to the concurrent techniques, so that it has been considered as inadequate for the research purposes. This study has shown that the fibre-metal laminate Glare absorbs between 60% and 80% of the apported impact energy during light impact events (ranging from 1 to Joules). Last, but not the least, materials stiffness was the most clearly and consistently imparted residual mechanical property (in a damage tolerance basis) due to the previous applied impact loading.

Aplicações dos laminados híbridos metal-fibra incluem, além da indústria aeronáutica, as indústrias naval e automobilística. Diferentemente do setor aeronáutico, pesquisas sobre impactos mecânicos nas duas outras áreas da mobilidade são freqüentemente limitadas pela disponibilidade de equipamentos laboratoriais, de modo que é desejável o desenvolvimento de procedimentos de baixo custo para a determinação da resistência e tolerância a danos por impacto dos materiais de construção. Neste trabalho, a resistência a danos por impacto transversal do laminado híbrido metal-fibra Glare-5® foi determinada via três diferentes metodologias. A primeira utiliza um aparato sofisticado aparato Laser-Doppler para monitorar a aceleração e desaceleração de um impactador esférico de aço com 5 mm de diâmetro durante o evento do choque mecânico. O segundo método se baseia apenas nos valores de carga (força aplicada) vs. o tempo de impacto para a obtenção da energia absorvida pelo material. O terceiro considera somente os dados da velocidade do impactador, ou projétil, imediatamente antes e após o impacto. Concluiu-se que os valores de energia obtidos segundo as duas primeiras metodologias são similares, com o Laser-Doppler gerando resultados levemente não-conservadores, comprovando assim a possibilidade da derivação da resistência ao impacto do laminado através de um experimento simples e rápido, que utiliza apenas uma célula de carga digital para a monitoração da força aplicada em função do tempo. O terceiro método apresentou resultados substancialmente superiores às duas primeiras metodologias, sendo classificado como inadequado aos propósitos do projeto. Determinou-se que o laminado híbrido Glare-5®; absorve entre 60% e 80% da energia disponibilizada em impactos ditos leves, no intervalo de 1 a 6 Joules. Por fim, comprovou-se que a rigidez do material (módulo de elasticidade) é a propriedade residual (numa base de tolerância a danos) mais clara e consistentemente degradada pelo impacto previamente aplicado ao material. / Applications of hybrid fiber-metal laminates include, besides aeronautical industry, the automotive and naval industries. Unlike aeronautical field, impact research activities in the former areas of mobility industry are frequently limited by available laboratory equipment, so that it would be desirable to develop low-cost procedures to determine impact resistance and tolerance properties of construction materials. In this work, the transversal (trans-thickness) impact resistance and tolerance of hybrid fiber-metal laminate Glare-5® have been determined via three different methodologies. The first one utilizes sophisticated apparatus comprising a Laser-Doppler device to monitor deceleration/re-acceleration of 5 mm-diameter steel-ball impactor during the mechanical shock event. The second approach merely relies on the force (applied load) vs. impact time for determining the absorbed energy during the dynamic process. The third methodology requires only impactor velocity data points, immediately before and after the impact. It has been concluded that the energy values obtained from Laser- Doppler and load cell methods are very similar, with the former method producing slightly non-conservative results, allowing one to rapidly derive the impact resistance of hybrid laminate materials through very simple experimental set-ups employing digital load cells only. The third method presented somewhat higher results as compared to the concurrent techniques, so that it has been considered as inadequate for the research purposes. This study has shown that the fibre-metal laminate Glare absorbs between 60% and 80% of the apported impact energy during light impact events (ranging from 1 to Joules). Last, but not the least, materials stiffness was the most clearly and consistently imparted residual mechanical property (in a damage tolerance basis) due to the previous applied impact loading.

3D woven composites, due to the presence of through-thickness fibre bridging, have the potential to improve damage tolerance and at the same time to reduce the manufacturing costs. However, the ability to withstand damage depends on weave architecture as well as the geometry of individual tows. A substantial amount of research has been performed to understand in-plane properties as well as the performance of 3D woven composites exposed to impact loads, but there is limited research on the damage tolerance and notch sensitivity of 3D weaves and no work is reported on the damage tolerance of 3D weaves with a weft binding pattern. In view of the recent interest in 3D woven composites, the influence of weft binder on the tensile, open hole tensile, impact resistance and subsequent residual compressive strength properties and failure mechanisms of 3D woven composites was investigated against equivalent UD cross-ply laminate. Four different 3D woven architectures; layer-to-layer, angle interlocked, twill angle interlock and modified angle interlock structures were produced under identical weaving conditions. All the above mentioned tests were performed in both the warp and weft directions on 3D woven and UD cross-ply laminates. Stress concentration and yarn waviness due to through-thickness reinforcement led to lower mechanical properties compared with the UD cross-ply laminate. However, improved in-plane and damage tolerance properties of 3D woven composites under tensile loads were achieved by modifying the weave architecture. The influence of the weave architecture and binder yarn orientation on the notch insensitivity and damage tolerance of 3D woven composites was less significant for compressive loads. Despite the lower undamaged compression strength of 3D woven structures, their residual compressive strength was found to be superior to their equivalent UD cross-ply laminates. The lower rate of strength reduction in the 3D woven fabrics laminates was attributed to a crack bridging mechanism, effectively inhibiting delamination propagation.