预拉伸对Al-Cu-Mg-Ag合金室温性能的影响

研究了时效前的预拉伸对高Cu/Mg比值的Al-Cu-Mg-Ag合金室温力学性能的影响.结果表明,预拉伸引起的位错促进θ′相的析出,同时位错在低温时效时不利于Ω相的析出,而高温时效则能够消除位错带来的不利影响.     

Structural Evolution of UHMWPE Fibers during Prestretching Far and Near Melting Temperature: An In Situ Synchrotron Radiation Small‐ and Wide‐Angle X‐Ray Scattering Study

Combining a homemade extension apparatus and the in situ synchrotron radiation small‐ and wide‐angle X‐ray scattering methods for measurement, the structural evolutions of gel‐spun ultrahigh molecular weight polyethylene (UHMWPE) fibers during prestretching at temperatures of 25 and 100 °C are investigated, respectively. Lamellar rotation toward the stretching direction occurs before strain hardening, while the folded‐chain crystal destruction and extended‐chain fibril formation processes occur in the strain hardening zone at 25 °C. While at 100 °C, stretching induced crystal melting before the stress plateau region and formation of fibrous crystals at the onset of the stress plateau are observed. Further stretching results in shear displacement of crystal blocks and, finally, destruction of the folded‐chain crystals and formation of extended‐chain fibrils. Prestretching UHMWPE fibers at 100 °C within a certain strain range can produce highly oriented fibrous crystals, which may provide an ideal precursor structure for the poststretching process.     

预拉伸光纤光栅应变传感器传感性能研究

为了提高光纤光栅测量应变的测量范围与测量精度,该文对基片式光纤光栅传感器应变传递理论及其有限元分析应力分布进行了阐述,并对光纤光栅应变传感器的制作工艺进行了探索。封装工艺与普通基片式光纤光栅传感器的不同是在制作时加载确定的预紧力,用等强度梁对预应力基片式光纤光栅传感器进行测试并标定,得到传感器灵敏度为0.88pm/με,线性度为0.996,传递效率为74%。并在MTS拉伸试验机上进行预紧力基片式光纤光栅传感器、裸光纤光栅传感器与电阻应变计压缩对比实验研究,实验表明,预拉伸制作工艺提高了光纤光栅测量压缩应变的线性度与测量范围。     

Aspects on prestretching of PAN precursor: Shrinkage and thermal behavior

Polyacrylonitrile (PAN) fibers of a special grade have been modified by a method of prestretching with various stretching ratios from negative to positive before the onset of stabilization. The effect of such pretreatments on the thermorhelogical and thermal behaviors of PAN fibers was followed by free shrinkage experiments and differential scanning calorimetry (DSC) analyses. It was found that prestretching had a significant influence on the physical shrinkage of PAN fibers. DSC results of PAN fibers showed dependence not only on atmospheric conditions but also on the extent of prestretching. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1185–1190, 1998     

预拉伸处理对Al-5.3Cu-0.8Mg-0.3Ag合金性能和时效过程影响

研究了时效前的预拉伸对耐热Al-5．3Cu-0．8Mg-0．3Ag合金时效过程和拉伸性能影响。结果表明,预拉伸降低了合金的时效硬化和耐热性能,延缓了时效过程,抑制了{111}。型Ω相的析出,但同时促进{100}。型θ’相的析出。     

世界先进的航空用铝合金厚板生产技术

介绍了世界主要航空用铝合金厚板生产厂概况，结合典型的航空用厚板生产工艺流程及其主要设备配置，就国外先进的航空用铝合金厚板生产加工技术特点进行了评论。     

铝板预拉伸机测控系统的设计与应用

阐述了5MN铝板预拉伸机测控系统的总体设计方案，硬件的组成、软件设计方法；通过预拉伸方法，有效的消除7050超厚铝合金因淬火引起的残余应力。     

固溶处理及预拉伸变形对2197铝锂合金组织与性能的影响

通过金相、扫描电镜、拉伸和断裂韧性试验等分析测试手段,研究了固溶处理温度及预拉伸变形量对2197铝锂合金板材组织和性能的影响。结果表明,2197铝锂合金在490～580℃温度范围内固溶再时效后,其强度随固溶处理温度的升高先增大后减小,强度峰值出现在540℃。当固溶处理温度高于565℃时,合金出现了再结晶现象。但是,合金在490～580℃固溶处理过程中均未出现明显的过烧现象。固溶处理后进行预拉伸变形可以有效提高合金的强度。综合考虑合金的强韧匹配,2197合金板材较优的固溶和预拉伸变形量分别为540℃×1.5 h和2%～5%。     

预张拉钢丝绳及其生产设备

分析钢丝绳伸长机理，介绍生产预张拉钢丝绳的方法及设备类型。     

预拉伸对硅橡胶介电性能的影响

以液体硅橡胶DC 186为基体,通过控制交联体系的用量制备了不同的硅橡胶薄膜材料,研究了交联程度对硅橡胶材料力学性能影响,研究了预拉伸程度和持续时间对硅橡胶材料介电性能的影响。结果表明,交联程度的增加会降低硅橡胶分子链运动中的能量损耗;由于预拉伸使得分子链上的极性基团活性降低,发生取向极化的概率减小,因此预拉伸程度越高、预拉伸持续时间越长,硅橡胶材料的介电常数越小,低频下的介电损耗越大。