The first part of the diploma thesis with name „Evaluation of dynamic damage of composite structure“ focuses on designing device for impact experiments and suitable laminate samples made from prepregs. The conditions and problems of impact tests are also demonstrated here. The second part of the thesis deals with non-destructive control of damaged specimens based on thermography. This is mainly the extent of defects in the impaired area and the evaluation of results using the pulse infrared thermography method. Finally, the relative deviation in the crack size comparison between the visual method and thermographic are compared. Consequently, the residual strength of the damaged samples against undamaged specimens are compared using bending tests.

<p>This paper is concerned with the newly reformed national English test for Chinese college students, called the College English Test (CET) Band 4 (or Level 4). By comparing the test before and after it was reformed, there will be a close examination with regard to the aspects of test reliability, construct validity, authenticity, interactiveness, impact and practicality. With an extra focus on how vocabulary and grammar are tested, the paper aims to investigate the extent to which the new system is considered useful and how effective it is in testing vocabulary and grammar.</p>

This paper is concerned with the newly reformed national English test for Chinese college students, called the College English Test (CET) Band 4 (or Level 4). By comparing the test before and after it was reformed, there will be a close examination with regard to the aspects of test reliability, construct validity, authenticity, interactiveness, impact and practicality. With an extra focus on how vocabulary and grammar are tested, the paper aims to investigate the extent to which the new system is considered useful and how effective it is in testing vocabulary and grammar.

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.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta pesquisa utilizou-se um equipamento experimental que utiliza o método do eco-impacto produzido no Laboratório de Ensaios Físicos do Instituto Politécnico do Rio de Janeiro (UERJ/IPRJ), para estimar a espessuras de placas de concreto através da propagação de ondas de tensão geradas por um impacto. Para determinação dessa espessura, foram investigados vários mecanismos de estruturação do protótipo do equipamento com objetivo de se obter a melhor leitura possível, por meio das literaturas existentes. Entre parâmetros avaliados no estudo, estava o modelo de sensor a ser utilizado, o tipo de impactor, a precisão relacionada à aquisição de dados e o tratamento do mesmo, a distância entre o ponto de impacto e o transdutor (sensor), e o local de teste. Os resultados experimentais concordam com as previsões teóricas e revelam que este método é eficiente para análise de estrutura de concreto. A análise da espessura e resposta em frequência de um novo protótipo desenvolvido e os testes realizados possibilitou um erro médio de espessura real para amostras sem agregados de 0,39% e para as amostras com agregados com de 0,64%. Esses resultados apontam que o equipamento produzido tem potencial e que o mesmo pode ser utilizado para avaliação de estrutura de concreto. / In this research we used an experimental device that uses the method of impact-echo on Physical Testing Laboratory of the Polytechnic Institute of Rio de Janeiro (UERJ/IPRJ), to estimate the thickness of concrete slabs through the propagation of stress waves generated by an impact. To determine this thickness, several mechanisms for structuring the prototype equipment in order to obtain the best possible reading by means of existing literatures were investigated. Among the parameters evaluated in the study was the model of sensor being used, the type of impact, the precision related to the data acquisition and processing thereof, the distance between the impact point and the transducer (sensor), and test site. The experimental results agree with the theoretical predictions and show that this method is effective for analyzing concrete structure. The thickness analysis and frequency response of a new prototype and testing allowed an average error of actual thickness for samples without aggregates and 0.39 % for samples with aggregates with 0.64 %. These results indicate that the product produced has potential and that it can be used for evaluation of concrete structure.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta pesquisa utilizou-se um equipamento experimental que utiliza o método do eco-impacto produzido no Laboratório de Ensaios Físicos do Instituto Politécnico do Rio de Janeiro (UERJ/IPRJ), para estimar a espessuras de placas de concreto através da propagação de ondas de tensão geradas por um impacto. Para determinação dessa espessura, foram investigados vários mecanismos de estruturação do protótipo do equipamento com objetivo de se obter a melhor leitura possível, por meio das literaturas existentes. Entre parâmetros avaliados no estudo, estava o modelo de sensor a ser utilizado, o tipo de impactor, a precisão relacionada à aquisição de dados e o tratamento do mesmo, a distância entre o ponto de impacto e o transdutor (sensor), e o local de teste. Os resultados experimentais concordam com as previsões teóricas e revelam que este método é eficiente para análise de estrutura de concreto. A análise da espessura e resposta em frequência de um novo protótipo desenvolvido e os testes realizados possibilitou um erro médio de espessura real para amostras sem agregados de 0,39% e para as amostras com agregados com de 0,64%. Esses resultados apontam que o equipamento produzido tem potencial e que o mesmo pode ser utilizado para avaliação de estrutura de concreto. / In this research we used an experimental device that uses the method of impact-echo on Physical Testing Laboratory of the Polytechnic Institute of Rio de Janeiro (UERJ/IPRJ), to estimate the thickness of concrete slabs through the propagation of stress waves generated by an impact. To determine this thickness, several mechanisms for structuring the prototype equipment in order to obtain the best possible reading by means of existing literatures were investigated. Among the parameters evaluated in the study was the model of sensor being used, the type of impact, the precision related to the data acquisition and processing thereof, the distance between the impact point and the transducer (sensor), and test site. The experimental results agree with the theoretical predictions and show that this method is effective for analyzing concrete structure. The thickness analysis and frequency response of a new prototype and testing allowed an average error of actual thickness for samples without aggregates and 0.39 % for samples with aggregates with 0.64 %. These results indicate that the product produced has potential and that it can be used for evaluation of concrete structure.