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

这项工作的总体目标是研究形状记忆合金在旋转机械中的应用。到目前为止，已经有可能建造一种轴承支撑件，其刚度可以通过施加电流来改变。这是一种非常理想的特性，因为它意味着振动响应可以被修改，并因此被控制。与格拉斯哥大学的同事们合作，到目前为止，已经开发出两种不同的系统来解决这个问题。在斯旺西采用的方法是在一对弹性O形圈中支撑实际轴承，其硬度是其压应力的函数。通过改变支撑滚动元件轴承的一对弹性O形圈上的载荷来控制支承的有效刚度。O形环的刚度受弹性体上的(静态)载荷的强烈影响，载荷由两组SMA钢丝施加，如图所示。欧姆加热被用来控制SMA导线的温度，并通过热电偶进行监测。SMA钢丝在图3中显示为单根钢丝，实际上包括多圈钢丝，其排列方式是为了给弹性体O形圈提供足够的压缩预载荷。这是一个简单的几何，只是用来证明概念。到目前为止的实验结果显示，非常有希望的结果，自然频率移动超过50%的电流。为了推进这项工作，将非常有益的小组成员在弗吉尼亚理工大学，他们中的许多人都有广泛的经验与SMA的应用。这次访问的附属部分，卡尔加里的轴承制造商是相同的一般情况下是‘智能机器’，尽管有一些不同的应用。

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.