No abstract

The tensile tests of three‐dimensional (3Dim) and four‐directional (4Dir) carbon fiber braided/epoxy resin composites and carbon fiber woven plain fabric laminated/epoxy composites after heat accelerated aging at 150 and 180°C for 60, 120, and 180 h were carried out respectively. The reason of the changes of tensile property of these composites after different aging period of time at different high temperature was explained. The results of two‐way ANOVA analyzing indicate that the aging time has a significant effect on tensile strength of these composites. With the increase of accelerated aging period of time at high temperature, the tensile strengths of these composite samples decreased compared with that of composite samples without aging. However the decrease of tensile strength of 3Dim and 4Dir braided composites is less than that of laminated composites. One of the reasons is after aging for a long time at high temperature, the resin is damaged and becomes brittle which make the bonding force between fiber and resin decrease. Another reason is the structure of reinforcement of composites. After aging, the structure of 3Dim and 4Dir braided/epoxy resin composites still keeps the integrity which makes the 3Dim and 4Dir composites have less tensile performance degradation (3Dim and 4 Dir: three‐dimensional and four‐directional). POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

It is believed that HSO3−and SO32−play important roles in several physiological processes.

In this study, the fiber-shift method is presented to generate the three-dimensional geometric model of carbon fiber needled felt, and curved carbon fiber is regarded as beam under pure bending. The finite mixture model is applied to describe the fiber length distribution for the experiments and models. Closed model, open model and cut model are proposed, and cut model is thought to be more close to reality. A series of analytical methods are proposed to investigate the full-scale three-dimensional geometric model. The fiber-length distributions of cut models with different dimensions are obtained. The results show that, with the increasing of border length of cut model, the percentage of carbon fiber been cut is getting smaller, and the average fiber length is increased. In addition, the compression and needling process of pre-needling technique are simulated, and the needling hole obtained by simulation is similar to reality.