Mechanical Behavior And Constitutive Model Of Fused Deposition PLA Materials

Fused-deposited polylactic acid（PLA）material molded parts have been widely used in automotive and aerospace fields,where static or dynamic loads are inevitable.Therefore,studying the mechanical properties of fused-deposited PLA materials under quasi-static and dynamic loads and establishing their intrinsic structure models related to parameters such as strain rate and temperature is essential for material property evaluation and optimization of fused-deposition parameters and thus advancingIn this paper,quasi-static compression tests of fused-deposited PLA materials at low strain rates(0.001,0.01,0.1s^-1)and dynamic compression mechanical tests at different ambient temperatures（25,50,80,110°C）were carried out using WDW-300A microcomputer electronic universal material testing machine and separated Hopkinson compression bar（SHPB）test device,respectively,and applied The digital image correlation（DIC）technique was applied to the strain analysis of the fused-deposited PLA material in the SHPB test.The experimental results show that there is a significant strain rate correlation between fused-deposited PLA materials at both low and high strain rates,and the initial compression modulus and yield strength of fused-deposited PLA materials show a significant increase when the strain rate increases.At the same time,fused-deposited PLA materials also have a temperature"softening"effect at high strain rates,where the initial compressive modulus and yield strength of fused-deposited PLA materials decrease as the temperature increases,and fused-deposited PLA materials undergo thermal deformation,resulting in a tough-elastic transformation and thus possessing some of the properties of elastic materials.The strain-time relationship measured by the DIC technique is consistent with the SHPB test data,which verifies the feasibility of the DIC technique and the accuracy of the SHPB test.To characterize the static and dynamic compressive mechanical behavior of melt deposited PLA materials,the constitutive models suitable for characterizing the compressive mechanical behavior of melt deposited PLA materials are constructed based on the Sherwood-Frost model and ZWT model,respectively.The applicability of the models is analyzed by comparing the stress-strain curves obtained from experiments with the fitting curves of the constitutive models.The results show that both the Sherwood-Frost model and ZWT model can well describe the compressive mechanical behavior of melt deposited PLA at low and high strain rates.This study can provide theoretical support for the follow-up research and development of FDM equipment and the practical application of melt deposited PLA products.Figure[36]table[9]reference[94]...