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并没有在很大程度上实现。这类材料的主要应用领域是医学（动脉支架、骨重建等）。以及消费品，如女性布拉斯和“非破坏性”文胸。 本计画将智能材料，特别是SEA，应用于高产能精密机械工具之结构。 SMA和SEA材料主要生产为线材、管材或带材。到目前为止，它们用于负荷调节的拉伸或弯曲模式，其中相对小的负荷引起相对大的变形。结构应用通常与高载荷和相对较小的变形相关。一项有限规模的初步（非资助）研究表明，如果由SEA制成的现成电线或管材径向加载，则可以适应非常高的力，同时引起小的变形。此外，人们发现，这种加载模式是与非常大的弹性极限。径向加载的SEA线表现出20- 24%的弹性极限，类似于橡胶类材料，同时具有比橡胶大至少一千倍的弹性模量（“巨大超弹性效应”）。这种独特的，直到最近还不为人所知的特性为有益的应用开辟了广阔的领域。 本项目将对各种SEA和SMA材料（线和管）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“巨超弹性效应”所需的数据。 将与Command Tooling Systems公司一起探索这种效应在刀柄上的应用。（美国最大的数控机床刀柄制造商之一）。根据以前的结果，结构尺寸补偿器的应用利用了径向-加载的SEA电线和管材将显着提高美国数千台机床的刚度和精度，从而提高其加工质量和生产率。这些效果将以非常经济的方式实现，对现有刀柄的修改最小。评估其他设计应用的巨型超弹性效应将进行，如模块化工具系统和可重构加工系统。

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.