Study On Damage And Strengthen Mechanism Of Holey Fiber And Section Parameters Design Based On 3-D Finite Element Analysis

The fiber technology has been developed from traditional fiber technology to new style holey fiber technology with the progress of modem science.Although the manufacture technology of holey fiber has been carried out perfectly,there will be some kinds of defects appearing in or on the surface of the fiber inevitably,for example the delamination between the core and the coating.In addition,micro crack appears on the surface of the holey fiber in the progress of application.The strength of holey fibers will be affected markedly if they get the defects above,and fiber will damage by the way of brittleness fracture.The economy loss caused by the brittleness fracture of holey fiber is incredible,the research in this paper is based on the above engineering background.In this paper,the ANSYS Parametric Design Language(APDL)is applied to research the damage and strengthen mechanism of holey fiber based on the 3-D finite element analysis technology.ANSYS Parametric Design Language(APDL)is advanced analysis technology of ANSYS. Modeling with parameters,applying load with parameters and solution,postprocessor by parameter would be realized by APDL.In the progress of finite element analysis,the user can change parameter of model to obtain all kinds of projects with different size and loads, analysis efficiency will be improved obviously.In this paper,different kinds of fibers will be taken into account,so the APDL is a better choice.In this paper,program and automatization of modeling are realized.The finite element models of naked fiber,the finite element models of coated fiber,the finite element model of fiber with delamination damage,the finite element model of fiber with cracks under different loadings and boundary conditions are realized by employing APDL.The conclusion obtained from this paper can be shown as follows:◆For fiber ASC026 and OD0036B,there are two highest stress areaⅠand areaⅡ,areaⅡshould be paid more attention.◆For the coated fiber,the high stress area will exist on the bonded end and loading end.If the parameters are chosen properly,stress of this area will be reduced obviously.◆For the holey fiber with delamination damage on the interface between fiber core and fiber coating,local maximum axial stress exists on the surface of delamination area.Delamination will develop due to this reason. ◆For the holey fiber with delamination damage,the dimension of delamination has obvious influence on local area axial maximum stress,the location of delamination has slight influence on local axial maximum stress;The dimension of delamination has slight influence on global axial maximum stress and the location of delamination has slight influence on global axial maximum stress.◆The global axial maximum stress of fiber with delamination damage exist on the surface of coating near the one side bonded surface.The coating of the fiber easily damages from this area,and the coating will disjoin from fiber core.◆For fiber with surface crack,crack depth and size are two key factors that effect stress intensity factor of crack front.◆Increasing thermal expansion coefficient of the coating material and the difference in temperature between the curing temperature and room temperature to generate higher closure stress,which can retard the crack propagation more effectively.