| With the development and innovation of industry, injection molding industry products become used more and more widely in people’s daily life and the quality of plastic products is very important. Structural foam material with highly specific strength, good impact resistance is widely used in plastic injection molding products. In this thesis, the structural foam material specimens and plastic pallets act as object, which have been conducted a study of the mechanical properties of structural foam materials, to understand the characteristics and performance of structural foam material parameters, to lay a good foundation for the subsequent structural design and development of foam materials products.Firstly, the topic idea for the project is from General Company overview of the structural foam material(GE plastic), and combines TRUST structural foam materials plastic pallet.According to the characteristic of structural foam material specimens, they have been equivalent to ‘I’- shaped model, Sandwich model, Return shape model, Microcellular model, Entity model. Meanwhile, to analyze and calculate the performance of the models on the same condition, the results of analysis have showed that Sandwich model is the most suitable equivalent model for the structural foam material. Parameters of each part of the model have been calculated through density testing of the structural foam material specimens, and the results obtain that cortical density of the sandwich model is 0.92g/cm3, core density is 0.56g/cm3, cortical thickness is 1.4mm. Three-point bending tests are performed on the structural foam specimen, raw material specimen, pure new material HDPE specimen by using a universal testing machine, and this obtains the bending modulus and bending strength of different kinds of materials.Then structural foam material specimens are established to the parametric models by using Pro/E.Based on the parameter identification of thought and specimens parameters ts, E1, E2 are set as the optimization parameters and the load-displacement values is the optimization target in simulation analysis bending test. It obtains the relevant parameters value of structural foam material: ts=1.17 mm, E1=576MPa, E2=273MPa. The result of bending test on the structural foam material specimens under the same conditions, shows that error is less than 5%, which meets the test requirements. Processing the plastic pallet as sandwich model and giving the analysis parameters of structural foam material to the model, bending strength and fork lift strength simulation test are performed on the sandwich model in workbench,and the test results show that the error of deformation in 8mm-12 mm interval is smaller, the modulus is larger when deformation is less than 8mm, the modulus is smaller when more than 12 mm. The results explain that the method of analysis has the feasibility and reliability of plastic pallets.Finally, PRA1210 plastic pallet has been taken as the analysis object, with the plastic pallet test standard ISO 8611 for reference, the test analysis model has been established in Pro/E. Stiffener is the most important part of the plastic pallet structural design. First step, the relationship between plastic pallet`s stiffeners parameters(DS_D, DS_H) and deformation is researched, at the same time, optimization parameters are analyzed by using Design Exploration module in Workbench, the results show the relationship between the thickness of stiffener DS_D, height of stiffener DS_H, deflection W and quality M, and show that DS_H is highly sensitive to deflection than thickness under the same quality, deflection changes with the value of H/D increases. According to the analysis of the plastic pallet PRA1210 and supporting legs, based on the results of the analysis of the displacement, stress contour, improving the structure of plastic pallet.The purpose of the study is further to understand the structural foam material, to understand its mechanical properties, and lay the foundation for the design and development of future related products. |
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