Multiscale Modeling And Simulation Of Mechanical Properties Of BMC Composite Materials

BMC is the abbreviation of Bulk molding compounds. BMC is athermoset plastic resin blend of unsaturated resin, chopped glass fibers,fillers and additives. In the1960s, the United Kingdom and the FederalRepublic of Germany started to apply BMC. In the1970s to1980s, Japanand the United States have made great progress in research for BMCmaterial.Some of Schneider Electric’s electrical components are made by BulkMolding Compound (BMC). They need to study the failure prediction ofBMC. In this paper, we use the multiscale mechanical modeling andsimulation to built the model of mechanical property and simulate themechanical behavior with Ansys.Firstly, we introduce the recognition of substrate’s microstructure ofBMC and the recognition of BMC’s microstructure. The curve of themechanical properties of the substrate is obtained by the tensile test. Theconclusion obtained finally is that the substrate is preferably isotropicduring the linear phase and during the nonlinear stage, the differencesamong different substrates appear clearly. After, ultrasonic detection forBMC is introduced. As a nondestructive testing method, ultrasonicmethod can detect the direction of the overall distribution of the choppedfibers. Additionally, we detected the different parts of the same sample.All of these proved that the analysis needs to be refined in different partsof distinction during predicting the failure of a BMC part.Then after comparing the development of the equivalent modulus ofthe composite material we use the Mori-Tanaka model two times todescribe the BMC containing voids and reinforcing fibers. We consider thechanges in material properties caused by the breaking and the shedding ofthe fibers and the increases of the holes. The means of how to simplify consider the distribution of the fiber and the use of discretization are takeninto account. But will also all fibers are unified into global coordinatesystem. While we use two kinds of failure criteria, one is the percentage ofshedding fibers; another is the pore energy criterion. The percentage ofshedding fibers criteria is based on statistical theory and the materialfailure when the damaged fibers in composite reach a threshold. The poreenergy criterion is based on mutual potential energy theory of solidmechanics, the material failure when the mutual potential energy caused bythe increase of the hole reaches a threshold. By modeling the relationshipbetween the macro-mechanical and micro-mechanical, we obtained theevolution of the mechanical properties of BMC.Next, according to the above-mentioned model, the description of themodel is realized by Matlab. The core program involves fiber’sclassification, how to unify the fibers into the global coordinate system,how to describe the equivalent modulus.In the end, Ansys software is used to simulate the mechanicalbehavior of simple materials and the parts. The evolution of themechanical properties from the Mori-Tanaka model is applied to the Ansyssimulation model. Tsai-Hill criterion and the Tsai-Wu criterion are addedto the Ansys simulation at the same time as the failure criterion. Therelated simulations in this article include virtual tensile tests and virtualbending tests. The differences of mechanical properties of20F-type BMCand15B-type BMC are compared. In the virtual bending test we also usesample which is mixed by the two types of BMC. Then a rapid predictionof failure of the parts is achieved in which the different positions are madeof different types of BMC. Finally, we compare the experimental resultswith the simulation results. The simulation result and the experimentalresults are consistent, but the improvement is still needed.