Research On Delamination Of Novel Composite Container Floor

Traditional container floor is 19 layers of plywood, manufactured by tropical broadleaf trees. However, the development of container floor industry have faced serious restriction because of the reduction of hardwood resource and the backward production technology, that is why the research of the container floor of alternative materials and structure optimization is extremely urgent.Sandwich structure is chosen to instead of plywood to be the structure of the container floor based on the normal stress distribution of the component resulting from bending deformation. A new kind of sandwich composite floor, which uses glass fiber reinforced epoxy resin matrix composites as panel and ABS plastic as the core layer, has been put forward under the consideration of comprehensive performance and production costs. The engineering elastic constants of unidirectional fiber board are predicted through series and parallel model according to the elastic constants of the glass fiber and epoxy resin curing agent. By taking composite delamination failure criterion as evaluation basis, the new container floors have carried on the numerical simulation based on orthogonal test design, and then four optimal schemes are obtained. The two constraint conditions of stiffness and bonding strength are determined by the operating requirements of container floor and common failure modes. The thickness of panel and the density of core layer are selected as the design variables of sandwich plate, after that an optimization program is written with the bending rigidity of unit mass as the objective function. The best technological parameters of four groups of solutions can be obtained by optimization programs.Drainage method is used to measure the density value of the epoxy resin curing agent and glass fiber, and then compression experiments based on different ratios of the epoxy resin curing agent are carried out to determine the best ratio. According to four groups of solutions based on different fiber angles and volume contents, the three-point bending test of the new sandwich floor has carried on the simulation. Results show that four groups of new sandwich structure plate can meet the design requirements. Corresponding sandwich plates are prepared for the three point bending tests that are used to verify the simulation results.A single parameter plasticity model is set up based on stress update algorithm which has been improved by the backward Euler method. User element subroutine(UEL) is written by FORTRAN language based on the above algorithm and through the finite element software ABAQUS compiling. After that this UEL is tested under the two different working conditions of uniaxial compression and cyclic loading. Calculation results consistent with test data obtained by other literature, which indicates the precision of subroutine meets the requirement of practical engineering. Finally, UEL is applied to the numerical simulation of unidirectional fiber reinforced composite board when bearing load in the plane, which verifies the accuracy of UEL in the simulation of fiber reinforce composite material.