应变速率对硬质聚氨酯准静态拉伸行为的影响

Effect of Strain Rate on Quasi-static Tensile Behavior of Rigid Polyurethane

在准静态范围内,对硬质聚氨酯进行了不同应变速率下的拉伸实验,根据应力-应变曲线研究其变形行为及力学性能与应变速率之间的相关性,通过观察试样断口形貌分析其破坏机理,应用Eyring理论对材料的弹性模量和屈服强度与应变速率之间的关系进行拟合。结果表明:在实验范围内,随应变速率增加,材料的弹性模量和屈服强度均呈现快速升高后逐渐趋于稳定的规律并符合Eyring理论的对数关系,而伸长率则显著减小至无明显强迫高弹形变;材料的破坏模式依次由软段大分子链主导过渡到软、硬段协同作用及硬段主导;依据研究结果,测量硬质聚氨酯弹性模量时应变速率应大于0.33×10^(-3)s^(-1),测量屈服强度时应变速率应大于1.52×10^(-3)s^(-1)。本工作旨在进一步揭示应变速率对聚氨酯树脂材料性能的影响,以期为相关研究与工程实践提供参考和借鉴。

Within the quasi-static range,tensile test at different strain rates was conducted on rigid polyurethane,and the correlation between the strain rate and its deformation behavior as well as mechanical performance was analyzed according to the stress-strain curve.Meanwhile,its fai-lure mechanism was analyzed through observing the fracture morphology of the test sample,and the relationship between the strain rate and the elastic modulus as well as yield strength of materials was fitted with Eyring theory.The results show that,within the experiment scope,the elastic modulus and yield strength of materials increase rapidly and they tend to be stable with the increase of strain rate,which conforms to the logarithmic relation of Eyring theory.Besides,the extensibility decreases remarkably till there is no remarkable forced high-elastic deformation.The material deformation behavior transits from the dominance of macromolecular chain in the soft segment,collaboration of soft and hard segments,and dominance of the hard segment.According to the research results,the strain rate shall be greater than 0.33·10^(-3)s^(-1)while measuring the elastic modulus of rigid polyurethane,and greater than 1.52×10^(-3)s^(-1)while measuring the yield strength.This paper aims to further reveal the impact of strain rate sensitivity on the performance of polyurethane resin material,so as to provide references for related research and engineering practice.