Experimental stress analysis is the strictly practical branch of stress analysis and for most problems it relies heavily on strain measurement techniques. Of these, by far the most widely used is that involving strain gauges in general and electrical resistance strain gauges in particular. These small and basically simple devices have been in use for many years, not only in all branches of engineering, but in almost all industries, and crossing all disciplines. In spite of ,

or perhaps because of ,their enormous field of application,there have been very few published books on the subject. Most of the literature consists of technical papers and reports, referring to specific problems or particular industries.

实验应力分析是应力分析中的一门实用性极强的分科，而且，就大多数问题来说，它在很大程度上依赖于应变测量技术。而应变测量技术中，迄今应用最广的方法一般都采用应变仪，特别是电阻应变仪。这些小型而且基本结构简单的装置已经使用多年了，不仅用于工程学的一切分科。而且用于差不多所有的工业部门，并且跨越了所有的学科。然而，尽管它们的应用范围极其广阔，但几乎没有出版过这方面的有关专著。（也许是因为它们的应用广，才没有这样做。)有关文献大部分都是技术论文和技术报告，它们论及的要么是特定问题，要么是专门工业部门的问题。

Strain Gauge Technology, which grew out of Applied Science Publishers' Developments in Stress Analysis series, does not replace or supersede existing text books and reference books. The basic theory of strain gauges has not changed, but the performance now available, and the techniques of installation, calibration, and data capture are very different to those used even a few years ago. There have been no revolutionary inventions; what has occurred is a very important steady improvement in materials, and in the techniques of both manufacture and installation, which has made strain gauges far more reliable, accurate, and versatile. They should now be the everyday tools of all engineers concerned with design, prototype testing, or development, as well as for failure analysis.

《应变仪技术》一书，虽是从应用科学出版家公司出版的《应力分析之进展》丛书中产生的，但它并不取代现有的教科书和参考书。应变仪的基本理论并没有改变，但其现有性能以及安装、校准和数据获取技术等，与即使是几年前所使用的也有很大的差异。虽然其间没有什么革命性的发明创造，但在材料方面以及加工方法与安装方法方而都已取得了非常重大的扎扎实实的进步，从而使应变仪更加可靠，更加精确，而且更加多样化。现在应变仪应该成为从事设计、样机测试或研制工作的所有工程技术人员的日常工具，也应该成为故障分析的日常工具。

The performance of precision transducers such as load cells and electronic weighing scales is now very much accepted and even taken for granted. It is often forgotten,or perhaps not known, that the sensors in these devices are usually resistance strain gauges. With commercial scales used in retail shops already offering accuracies of 0.33% and approaching 0.02% here is a true indication of the performance and reliability available from resistance strain gauges.

像测力计和电子称这类精密传感器，其性能可靠，这点已得到人们的普遍承认，甚至被认为是理所当然的。但人们却常常没注意到（或许前们不知道)这些装置里的敏感元件往往都是电阻应变仪。零售商店使用的商品称的精度，在此地已经达到0.33%，并接近0.02%，就是电阻应变仪所能获得的优良性能与可靠性的明证。