Use of Giant Superelasticity Effect for Improving Interface Performance

通过使用形状记忆和超弹性合金(SMA和SEA)等“智能材料”来推进机械设计的承诺得到了大力宣传，但并没有在很大程度上实现。这些材料的主要应用是在医学上(动脉支架、骨重建等)。以及消费产品，如女式胸罩和“不可损毁”的眼镜框。该项目将把智能材料，特别是SEA的应用扩展到高生产率精密机床的结构中。SMA和SEA材料主要以电线、管材或带材的形式生产。到目前为止，它们被用在拉伸或弯曲模式的载荷调节中，其中相对较小的载荷引起相对较大的变形。结构应用通常与高载荷和相对较小的变形有关。一项有限规模的初步(非资助)研究表明，如果从海上制成的现成的电线或管道是径向加载的，则可以容纳非常高的力，同时造成小的变形。此外，还发现这种加载方式与极大的弹性极限有关。径向加载的海丝具有20%-24%的弹性极限，类似于橡胶类材料，但弹性模量至少比橡胶大1000倍(“巨型超弹性效应”)。这一独特的、直到最近还不为人所知的物业为有益的应用打开了广阔的领域。在本项目的过程中，将对各种SEA和SMA材料(线材和管材)在径向载荷下的性能进行详细的实验和分析(有限元建模)研究，以积累在结构设计应用中使用“巨型超弹性效应”所需的数据。将与Command Toing Systems Co.(美国最大的数控机床刀架制造商之一)一起探索这种效应在刀柄中的应用。基于先前的结果，预计利用径向加载的海丝和管的独特弹性特性的结构尺寸补偿器的应用将显著提高美国数千台机床的刚度和精度，从而提高它们的加工质量和生产率。这些效果将以非常经济高效的方式实现，只需对现有刀柄进行最小程度的修改。将对巨型超弹性效应的其他设计应用进行评估，例如用于模块化工具系统和可重新配置的加工系统。

The much promoted promise of advancing mechanical design by using such "smart materials" as shape memory and superelastic alloys (SMA and SEA) did not materialize to a significant degree. The main applications of such materials are in medicine (arterial stents, bone reconstruction, etc.) and consumer products such as women's bras and "non-destructible" eyeglass frames. This project will extend application of the smart materials, especially of SEA, to structures of high productivity precision machines machine tools. SMA and SEA materials are largely produced as wires, tubing, or strips. Up to now, they were used in tensile or bending modes of load accommodation, wherein relatively small loads cause relatively large deformations. Structural applications are usually associated with high loads and relatively small deformations. A limited scale preliminary (non-funded) study demonstrated that very high forces can be accommodated while causing small deformations if the off-the-shelf wires or tubing made from SEA are loaded radially. Moreover, it was discovered that such loading mode is associated with extremely large elastic limits. The radially loaded SEA wire exhibit elastic limit 20-24 percent, similar to rubber-like materials, while having elastic modulus at least one thousand times greater than rubber ("giant superelasticity effect"). This unique and until recently not known property opens large areas for beneficial applications. Detailed experimental and analytical (finite element modeling) studies of properties of various SEA and SMA materials (wires and tubing) under radial loading will be performed in the course of this project, to accumulate data necessary for using the "giant superelasticity effect" in structural design applications. Application of this effect for toolholders will be explored, together with Command Tooling Systems Co. (one of the largest US manufacturers of toolholders for CNC machine tools).It is anticipated, based on the previous results, that application of structural dimensional compensators utilizing the unique elastic properties of the radially-loaded SEA wires and tubing will result in a significant enhancement of stiffness and accuracy of many thousands machine tools in the U.S., thus in increasing their machining quality and productivity. These effects will be achieved in a very cost-effective way, with minimum modifications of the existing toolholders. Assessment of other design applications of the giant superelasticity effect will be performed , such as for modular tooling systems and for reconfigurable machining systems.