Impact Response And Energy Absorption Characteristics Of Epoxy Based Composite Foam

Composite foam is a new type of multi-functional composite,which has low density,light weight,high strength,high specific strength and good shock absorption performance.In addition,composite material is widely used as heat insulation,sound insulation and energy absorption materials due to its excellent sound insulation,heat insulation and durability.In order to explore the dynamic response and failure mechanism of hollow glass microsphere reinforced epoxy resin composites under impact load,in this paper,bisphenol A epoxy resins was used as the matrix and hollow glass beads was used as the filler.Five kinds of bead content epoxy based composite foam were prepared.Through quasi-static compression and drop weight impact tests,the effects of bead filling amount and impact energy on the compressive strength,elastic modulus,energy absorption rate and energy evolution of composite foam materials were studied and analyzed.The quasi static compression test shows that when the content of microbeads is between5% and 10%,the elastic modulus of the material decreases by about 3% and 1.8%,respectively.When the content exceeds 10%,the reduction range becomes larger,about 4%and 6%.The elastic modulus increases slightly when the content is 10%.According to the stress-strain curve and failure patterns,materials can be summarized into three compression failure modes based on the crack propagation characteristics: vertical splitting,waist drum cracking,and oblique splitting.The results show that the addition of micro beads can effectively improve the toughness of epoxy resin and avoid brittle failure.The overall impact response characteristics of hollow glass bead toughened epoxy resin matrix composites were studied through a drop weight impact test.The impact load,impact energy and energy density curves of the composites under different impact velocities and bead content were obtained.The maximum impact force,energy absorption and energy storage limits were compared.The results show that impact velocity and bead content are the main factors affecting the impact resistance of hollow glass bead/epoxy resin composites.When the impact velocity is 6 m/s and 8 m/s,the toughness of the specimen with a bead content lower than 20% is better.With the increase of micro bead content,the overall stiffness of the material increases significantly and the failure has a significant brittle characteristic.When the impact speed reaches 10 m/s and 12 m/s,the energy absorption and load variation of the sample with a content of more than 10% are lower than those of pure epoxy resin.When the content of hollow glass beads reaches 10%,the energy storage limit of the material is relatively high,and the dissipation energy density is small,with good impact resistance and energy absorption capacity.In order to study the energy evolution law of the impact failure process,the energy evolution of the quasi static compression failure process is first analyzed using parameters such as input energy,elastic energy and dissipated energy.Then,the dynamic energy density is calculated to define the energy storage limit,dynamic linear elastic stage,dynamic yield stage and plastic failure stage.The dynamic failure process is divided into four stages,The relationship between energy density and impact failure morphology at each stage was analyzed.It is found that the specimen enters the yield stage when the dissipated energy density begins to increase.After experiencing a brief plastic plateau,elastic energy density curve begins to decline or decreases to the plateau stage.The specimen undergoes failure or uneven crack development.Based on the finite element software ANSYS workbench,the influence of different filling ratios on the dynamic compression performance of composite foam was simulated by using a three-dimensional finite element model.