Numerical Simulation Of Resin Flowing In 3-dimensional L-shaped Fiber Preform

Over the years,the process of resin infiltrating fiber preform has been regarded as Newtonian fluid flowing in single-scale porous media.However,fiber preform tend to have a dual-scale porous media characteristic in the actual production.In recent years,researchers found that there is a half-saturation region moving with flow front near the upstream of flow front during the resin flowing in dual-scale porous media.With gradually deepening understanding of dual-scale effect,immersed model has been proposed by some scholars to study resin flowing in a dual-scale porous media.The flowing characteristic of resin in 1-dimensional and 2-dimensional dual-scale porous media has been many research,but rarely involved in the numerical simulation of resin flowing in 3-dimensional dual-scale porous media.However,both of the practical engineering problems are complex 3-dimensional problems.So the research on 3-dimensional problems has more practical value.Therefore,the simulation of resin flowing features in 3-dimensional dual-scale porous medium fiber preform has important reference value for LCM processes.In this thesis,the main work and content are as follows:1.The basic principles of the finite element method have been introduced.And the specific steps of forming finite element equation on hexahedral element have been introduced in detail.2.The pressure control equation of resin flowing in dual-scale porous fiber preform is established by using the method of volume homogenization.And the mathematical expression of sink term is deduced.At last,the boundary conditions of resin filling process are set,then a complete mathematical model is established.3.The finite element equation of pressure field is set up when resin flows in three-dimensional preform.The 3-dimensional L-shaped skew template is dispersed by hexahedral elements.Algorithms are designed and PATRAN programs are compiled.Then the displace distribution of different time,the pressure distribution and the filling time of different displace in the mold cavity are tracked by using control volume method at constant pressure when resin flowing 3-dimensional L-shaped fiber preform.4.The results of numerical simulation show that: under the same conditions,it takes longer time that resin flows in dual-scale porous medium than in single porous medium.And the greater the pressure,the less filling time spent.Near the inlet,greater pressure results in greater gradient of pressure dropping,and the filling volume of cavity increases rapidly.So less filling time is spent near the inlet.With the volume of unfilled cavity is smaller and smaller,there is less pressure father away from the inlet.Then the gradient of pressure dropping is less.Therefore,more time is spent to reach saturation father away from the inlet.