Investigation On Mechanical Properties Of 2D Laminated And 3D Orthogonal Woven Composites And Design Of 3D Sandwish Structure

Since 1960,the advanced composite,especially the advanced resin matrix composites,has been greatly developed in the world for its unique characteristic,and it has been one of the most important materials of modem aerospace industry.Because of the whole woven of introducing Z-direction,three-dimensional woven composite materials overcome the defects of the traditional laminate composite and improve the whole performance in each direction,and will widely apply in many industries, such as aerospace industry etc.This research includes two aspects:"Investigation on Mechanical Properties of 2D laminated and 3D Woven Composites" and "Design of 3D Sandwich Structure Composite".In the first part,the weaving technique,molding technics of three-dimensional woven composite and mechanics- performance study method are summarized.The E-glass continuous reinforced fiber was used to manufacture the three-dimensional orthogonal woven fabric.The size of the fiber were 2400tex,1200tex and 200tex.The 3-D orthogonal weaving machine was designed by the National Textile Fabric Key Laboratory of Donghua University.After the weaving,the Vacuum Assisted Resin Transfer Molding process was used to manufacture the 3-D composite.In order to increase the fiber volume content and keep a stable level,a pressure was puted on the mould before solidifying of the resin.Vinyl resin was used.According to the mechanical tests of 2D laminated and 3D Woven Composites,the compression property of 3D woven composite is better than 2D laminated composite.It’s mainly because under the tension of the machine,as a entirety,there are less flexural wave in warp yarn and weft yam,better fiber failure simultaneous.In addition,Z-yarn in the warp direction lead to the excellent property of 3D woven composite. Meanwhile,3D woven composite has better shear strength,especially in warp direction.It shows in the load-displacement curve of shear strengh test,2D laminated composite had failured under small strain.However, the strain of 3D woven composite is twice the length than 2D laminated composite.It’s also the effect of Z-yarn.After partial failure,Z-yarn can support the structure and enhance the composite,so it concludes that the mechanical property is better than 2D laminated composite.In the second part,preliminary study on Design of 3D Sandwich Structure Composite was done,to increase the thickness,save the weight and improve the stiffness greatly is the objective of the research.To meet the weaving demand of the sandwich structure,six harnesses were used rather than two harnesses.And the control system was designed to be more flexible.Kevlar49 and PVC foam were used because of its low weight.This unique composite has many advantages such as high strength/stiffness and low density,excellent through- thickness properties, low dielectric constant and low dielectric loss.So it can be widely used in the commercial and industrial areas,which include aerospace,automotive, marine engineering,satellites,sports goods,radar antenna cover and so on.