Investigation of Highly Designable Dented Structures in HP Model with Hydrogen Bond Energy

Some highly designable protein structures have dented on the surface of their native structures, and are not full compactly folded. According to hydrophobic-polar （HP） model the most designable structures are full compactly folded. To investigate the designability of the dented structures, we introduce the hydrogen bond energy in the secondary structures by using the secondary-structure-favored HP model proposed by Ou-yang etc. The result shows that the average designability increases with the strength of the hydrogen bond. The designabilities of the structures with same dented shape increase exponentially with the number of secondary structure sites. The dented structures can have the highest designabilities for a certain value of hydrogen bond energy density.     

如何减少注塑件凹痕

从凹痕的产生原因、凹痕的危害性及如何避免凹痕的产生等几方面对凹痕进行介绍。     

基于ABAQUS的拖锚载荷对海底管线的影响研究

锚击是造成海底管线第三方损伤的重要因素.本文将拖锚对海底管线的损伤分为撞击、拖曳两个方面,并利用ABAQUS软件对上述两种作用方式进行数值模拟.撞击分析中,利用数值模型分析了管壁厚度、管线长度对最终凹痕深度的影响,并与其他撞击形式、规范计算值进行了对比.拖曳分析中,重点探讨了海床土壤性质的影响.结果表明,拖锚对海底管线的撞击作用影响相对较小,平铺于砂质海床上的管线最大拖曳力计算值更大.应用ABAQUS的有限元模型研究海底管线的抗锚害问题切实可行,对于管线设计、提高管线安全性有一定指导意义.     

X80管道凹痕缺陷失效准则对比分析

为了提高油气管道凹痕缺陷安全评价的准确性,将金属材料的韧性失效准则应用到管道凹痕的损伤评价中。以X80管道凹痕为例,采用有限元法计算不同工况下3种失效准则的管道损伤量并作对比分析。研究发现,管道损伤量随凹痕深度的增加而增加;当凹痕深度大于6%管道外径时,管道损伤量的增长速率减小。其中,Oyane韧性断裂准则计算出的损伤量最大,临界空穴扩张比判据理论次之,而X-W损伤失效准则计算的损伤量最小。此外,通过研究凹痕缺陷的类型对损伤量的影响发现,Oyane韧性断裂准则能更好地反映管道凹痕区域的应力集中。研究结果表明,Oyane韧性断裂准则更适合用于深度较大以及不同种类的管道凹痕缺陷的评估。为进一步研究韧性失效准则在管道凹痕评价中的应用提供参考。     

Deformation behavior during nanoindentation in Ce-based bulk metallic glasses

Recently, bulk metallic glasses (BMGs) have at- tracted a great deal of attention due to their extremely high strength, improved wear resistance and excellent corrosion resistance[1-7]. However, it is known that their structural applications are currently…