【摘要】 以天然橡胶为例,采用分子动力学模拟方法,研究了单轴拉伸条件下材料分子链聚合度参数p、环境温度T和加载率R对黏弹性材料力学性能的影响.结果表明,材料应力随分子链聚合度和加载率的增加而增加,随温度的升高而降低,低温高频下材料呈现出塑性特点.在R=10⁸ s^-1,T=250 K的条件下,p=20,40时,材料应力峰值分别为79.8和99.8 MPa;当p=40,R=10¹⁰ s^-1时,T=100,250 K条件下,应力幅值分别为134.9和103.9 MPa;在p=40,T=250 K情况下,R=10⁹,10¹⁰ s^-1时,应力峰值分别为122.7和134.9 MPa.在加载过程中,非键结势能对系统总势能的变化起主导作用,分子动力学模拟方法可以较好地分析分子链聚合度、环境温度和加载率等参数对黏弹性材料应力、系统能量和自由体积变化的影响.更多还原

【Abstract】 Taking natural rubber as an example, the effects of the material molecular chain polymerization degree p, the ambient temperature T and the loading rate R on the mechanical properties of viscoelastic materials under uniaxial tension conditions are investigated by using the molecular dynamics simulation method. The results show that the material stress increases with the increase of the polymerization degree and the loading rate, and decreases with the increase of the temperature. The material presents plastic characteristics at low temperature and high frequency. With the situation of R=10⁸ s^-1 and T=250 K, the material stress peaks are 79.8 and 99.8 MPa, respectively, when p=20, 40. As p=40, R=10¹⁰ s^-1, under the conditions of T=100, 250 K, the stress amplitudes are 134.9 and 103.9 MPa, respectively. In the case of p=40, T=250 K, when R=10⁹, 10¹⁰ s^-1, the stress peaks are 122.7 and 134.9 MPa, respectively. In the loading process, the non-bonding potential energy plays a leading role in the total potential energy variation of the system. The molecular dynamics simulation method can be used to anaylze the effects of the molecular chain polymerization degree, the ambient temperature and the loading rate on the changes of the stress, the system energy and the free volume of viscoelastic materials.更多还原