Experiment Study On Fabrication And Mechanical Properties Of Three-dimensional Aramid Woven Composites

With high integrity, good shape weaving and outstanding designability, as well as can be produced in a higher production efficiency by ordinary equipment orequipment with a little modification, 3D woven fabric composite material is becoming more and more popular in various fields. However, structure of 3D woven fabric is various and complex. Fabrics with different structures show different mechanical properties. So studying the relationship between the 3D woven structures and the mechanical properties of composites which was enforced by these structures has great significance to the development of 3D woven fabric composite materials.All the works in this paper can be divided into two parts. First, by the loom for weaving small sample in the lab, using Twaronfiber,three-dimensional woven fabrics with the same layers such as six layers orthogonal organization, six layers enhanced orthogonal organization, six layers angle-interlock, six layers enhanced orthogonal and six layers multilayer fabrics are weaved. Tensile and bending tests were made to the five kinds of fabrics, and measured results were analyzed in the paper.Second, complexed orthogonal woven fabric, angle interlocking fabric and multi-layer stitching fabric with resin respectively and test the tensile as well as bending properties of these three 3D woven fabric composite materials and then make a comparison between these result data with the result data of different laminated composite materials,and analysis their mechanical performance. Some conclusions can be found in these tests. The mechanical properties of the fabrics and its composite materials are affected by the arrangement ways, buckling degree and the density of mainly stress-bearing yarns in the 3D woven fabrics.And within a certain range of density, the buckling degree of the yarns does bigger effect on the stress than density. Generally speaking, if the buckling degree of the main stress-bearing yarns as well as the angle between the mainly stress-bearing yarns and the stress are small, or the density of the stresses-bearing yarns is big, the biggest strength which thesample can bear in the stress direction will be enlarged. So,multilayer plain fabrics and its reinforced composites own the highest tensile strength in the warp direction, but lowest tensile strength in the weft direction.The increasing of the Z-binders in the orthogonal structures will reduce the tensile strength of its fabrics and its reinforced composites while improve their bending strength at the same time.With the increasing of the stuffer liner yarns, rigidity andbending strength of the angle interlock fabrics and its composites being improved, at the same time the tensile breaking loads that they can bear becoming bigger while their tensile stresses becoming small. The main reason that fabric layer’s increasing in laminated composite can enhance its tensile stress is that the density of the stress-bearing yarns has been increased. But, the laminated composite is prone to spalling in the stretching process. The increasing of the fabric layers in the laminate can improve its bending strength. Under the same thickness,the biggest breaking load of the fabric has positive correlation with its surface density but the bulk density. The influence on the mechanics performance of the compound material by fabric’s areal density, composite’s surface density, bulk density, fiber column fraction and other parameters is smaller than the influence by the yarns’ arrangement ways and straight or crimp state under the same porosity. Under the same fabric structure, the bigger the fiber volume fraction andthe fiber weight fraction are, the higher the strengths of the fabric and its composite are. To the different sample with different fabric structures but the same straight degree of the stress-bearing yarns, the one which won the biggest fiber volume fraction of the bearing-yarns can show the high strength.So, it can be conclude in this paper that orthogonal woven fabric and its composite material own the highest comprehensive strength, and the orthogonal is the most suitable structure for the armored vehicle and aerospace materials. But the problem of that the increasing of the Z-binder yarns’ content will reduce the composite materials’ warp tensile strength should be taken into consideration when design the fabrics which was used for the armored vehicle and aerospace materials. The consistent of the fiber volume content both in the warp and weft direction can decrease the composites’ anisotropy. It is better to reduce the buckling degree of mainly load-bearing yarn when design the fabrics. If the thickness is confirmed, improving the fabric’s surface density can increase the composite materials’ breaking strength of the composite materials.