Visit to Virginia Tech, Blacksburg, Virgingia, USA and Revolve, Calgary, Canada

这项工作的总体目标是形状记忆合金在旋转机械中的使用的调查。到目前为止，工作中已经出现了这样一种可能，即可以构造一种轴承支承，其刚度可以通过施加电流来改变。这是非常理想的特性，因为它意味着振动响应可以被修改，因此可以被控制。通过适当的循环，这导致了所谓的“智能机器”。与格拉斯哥大学的同事合作，到目前为止已经开发了两个不同的系统来解决这个问题。斯旺西采用的方法是用一对弹性体O形圈支撑实际轴承，O形圈的刚度是其压缩应力的函数。通过改变支撑滚动元件轴承的一对弹性体O形环上的负载来控制支撑件的有效刚度。O形环的刚度受到弹性体上的（静态）负载的强烈影响，并且负载由两组SMA线施加，如图所示。欧姆加热用于控制SMA线的温度，并通过热电偶进行监测。SMA线（在图3中示出为单根线）实际上包括多圈线，如此布置以便为弹性体O形环提供足够的压缩预载荷。这是一个简单的几何形状，只是用来证明这一概念。迄今为止的实验结果显示出非常有希望的结果，当施加电流时，自然频率被移动了50%以上。为了推进这项工作，与弗吉尼亚理工大学的小组成员进行讨论将是非常有益的，他们中的许多人在SMA应用方面有着丰富的经验。这次访问的附属部分，卡尔加里的一家轴承制造商在同一个一般都是“智能机器”，虽然有点不同的应用。

The overall aim of this work is the investigation of the use of shape memory alloys in rotating machinery. It has emerged from work so far that it is possible to construct a bearing support whose stiffness can be modified by the application of an electric current. This is a highly desirable property as it implies that the vibrational response can be modified, and therefore controlled. With the appropriate loops, this lead to a so-called 'Smart Machine'.Working with colleagues at University of Glasgow, two distinct systems have so far been developed to address this problem. The approach followed at Swansea has been to support the actual bearing in a pair of elastomer O-rings, whose stiffness is a function of their compressive stress. The effective stiffness of the support is controlled by varying the loading on a pair of elastomer O-rings which support the rolling element bearings. The stiffness of the O-rings is strongly influenced by the (static) loading on the elastomer and the load is applied by two sets of SMA wires as shown. Ohmic heating is used to control the temperature of the SMA wires and this is monitored by means of thermocouples. The SMA wires, shown as a single wire in figure 3, actually comprise a multiloop of wire, so arranged in order to provide sufficient compressive pre-load for the elastomer O-ring. This is a simple geometry which is employed merely to prove the concept.Experimental results to date show very promising results, with natural frequencies being shifted by more than 50% as current is applied.To take this work forward it would be highly beneficial to discuss with members of the group at Virginia Tech, many of whom have extensive experience with SMA application.The subsidiary part of this visit, to a bearing manufacturer in Calgary is in the same general are of 'Smart Machines', albeit a somewhat different application.