车用胶粘剂载荷老化特性研究

为了研究车用胶粘剂在服役过程中,动态载荷对胶粘剂老化特性的影响,本研究对单搭接接头和对接接头试件的胶粘剂在不同载荷水平作用下进行疲劳试验,并与标准哑铃型Q235钢试件的疲劳试验结果进行了对比。研究结果表明:胶粘剂与金属材料的抗疲劳能力存在明显的差别。经过循环载荷作用,金属材料的剩余强度几乎没有变化,载荷水平和疲劳循环次数对其失效强度几乎不产生影响;而在循环载荷作用下,随着疲劳次数的增加,胶粘剂的剩余强度逐渐衰减,并且载荷水平越大,剩余强度衰减越明显。除此之外,研究还发现对接接头抵抗载荷老化的能力较单搭接接头更强。

汽车用胶粘剂的动载荷老化行为研究

对比分析了两种胶粘剂(S265和B7)制成粘接件的动载荷老化行为,考察了载荷水平对粘接件剩余强度的影响。研究结果表明:S265剪切粘接件和拉伸粘接件的初始强度都要高于B7粘接件,S265和B7粘接件的失效疲劳循环次数都随着载荷减小而增大。在不同载荷下,S265和B7粘接件的剩余强度都会随着疲劳循环次数增加而逐渐减小;在S265和B7粘接件的拉伸或者剪切载荷老化试验过程中,纯拉伸和纯剪切试件的疲劳循环次数随着载荷的变化规律相同,都表现为随着载荷增加,粘接件的疲劳循环次数呈现逐渐升高的特征;在相同载荷作用下,剪切粘接件的疲劳循环次数都低于拉伸粘接件。B7粘接件抑制载荷老化的能力会优于S265粘接件,且相较于拉伸粘接件,剪切粘接件的强度受载荷老化的影响更大。

Correlation of Cooperatively Localized Rearrangement on the ＂Fluidized Domain＂ of Polymers to Their Nonexponentially Viscoelastic Behavior and Lifetime at Double Aging Processes II： Estimation of Long-term Mechanical Behavior and Lifetime of Polymeric Materials from Short-time Creep and Stress Relaxation Tests

Three kinds of polymeric materials are taken as example for the verification of linear ex-trapolation method from unified master lines with reduced universal equations on creep and stress relaxation tests. The theoretical values of long-term mechanical behavior and lifetime for a cured epoxide, polypropylene, poly（methyl-methacrylate）, and SBR rubber are directly evaluated with the universal equations on reduced creep compliance and reduced stress relax-ation modulus and are compared with their predicted values by the linear extrapolation from the unified master lines of creep and stress relaxation. The results show that the theoretical values of dimensional stability, bearing ability and lifetime are in an excellent agreement with the predicted values, it shows that the linear extrapolation method is more simple and reliable. The dependences of long-term mechanical behaviors and lifetime on the different aging times are discussed.