# Strain Gauge Fundamentals

Strain gauges have been around for almost 80 years and continue to be key assets for measuring fatigue and testing materials for productivity and safety reasons. But how do I calculate material stress from strain? How can I select the right strain gauge and install it correctly? Our experts dug deep to provide their best answers for you about all the important questions regarding strain measurement using strain gauges. Click an option below to direct you to the content on the page.

## 1. Basics of Strain Measurements and Experimental Stress Analysis

### How does an electrical strain gauge work?

Strain gauges are used in thousands of applications. This video shows you in just 2 minutes how this exciting sensor works!

### Strain measurement glossary

You can benefit from our practical on-line glossary by looking up the most important technical terms in the field of strain measurement.

### Experimental Stress Analysis (ESA) using strain gauges

The principle of Experimental Stress Analysis (ESA) consists in using strain gauges to measure the strain on a component's surface. The absolute value and direction of the mechanical stress is determined from the measured strain and known properties of the material (modulus of elasticity and Poisson’s ratio). These calculations are based on Hooke’s Law that is applicable to the elastic deformation range of linear-elastic materials. Learn more by clicking here.

### The Wheatstone bridge circuit

The Wheatstone bridge is well suited for the measurement of small changes of a resistance and is therefore, also suitable for measuring the resistance change in a strain gauge. It is commonly known that the strain gauge transforms the strain applied into a proportional change of resistance. Find out more about the application of Wheatstone Bridge Circuits here.

### The reference book on Experimental Stress Analysis using strain gauges

Get a complete overview of the topic of "An Introduction into Measurements using Strain Gauges" - Karl Hofmann's 250-page reference book.

## 2. Selecting the Right Strain Gauges, Adhesives, Covering Agents and More

### How to select the right strain gauge

HBM offers a wide range of strain gauges that are suitable for almost every measuring task. But how do you find the right strain gauge? Here you will get the complete information to help you find the right strain gauge for your needs in an easy and straightforward way.

### How to select the right adhesive

Strain gauges are usually applied to the surface of the object to be measured using adhesives. Here you can learn how to select  the correct adhesive based on the material and temperature range. This page also provides tips for preparing a measuring point to ensure good bonding for strain transfer.

### How to select the right covering agent

The quality of measurement with strain gauges  essentially depends on the type of installation and design of the measuring point. A thorough preparation of the installation surface, correct connection, and protective covering are important factors for obtaining problem-free results.

## 3. Installation of Strain Gauges: All There is to Know

### How to prepare material for a strain gauge installation

Click here for a quick overview of how you can prepare your material for effective strain gauge installation. By applying the suggestions provided by our highly-skilled experts, you can achieve a successful installation on concrete, plastics, fiber-reinforced material, among others.

### How to install a strain gauge

This training video shows you all the necessary step-by-step instructions for a successful strain gauge installation. No measurement skills or previous installation experience is required.

### How to weld a strain gauge

Some environments are not suitable for bonding of strain gauges owing to very low temperatures or excessive dust formation, e.g. at construction sites. Weldable strain gauges are the best choice for being used in these kinds of environments. Watch our video on how to weld your strain gauge correctly.

### Tips for installing strain gauges

In many cases, measuring the strain on an object is done within a short timeframe. If the strain gauge is improperly installed, false measurements can be obtained. Watch this video to learn how to install gauges in the most effective way.

### Practical hints for the installation of strain gauges

Get a complete overview of the topic of "Practical Hints for the Installation of Strain Gages"- in Karl Hofmann's reference book.

## 4. Reduction and Elimination of Measurement Errors

### Measurement uncertainty: Less errors, better results

There are certain possible sources of error when strain gauges are used for experimental stress analysis. Learn how to successfully assess measurement uncertainty already in the design stage by clicking on the title above.

### Temperature effects on measurement results

Unwanted temperature effects can affect the measurement results while using strain gauges. Find practical assistance on how to minimize these effects or compensate for them entirely. Learn more by clicking on the title above.

In particular, electrical resistance changes in the cable connecting the measuring points to the measuring device, such as temperature variations, have negative effects in the measurement. Click above to find out more.

## 5. Acquiring Data with the Right Hardware and Software

### How to work with strain gauges in catman AP

In this tutorial you will learn how to set up strain gauge rosettes using HBM's catman®AP data acquisition software and QuantumX MX1615 data acquisition system.

### How to calibrate strain gauges with shunt signals

In the field of experimental stress analysis hundreds and sometimes thousands of single strain gauges must be measured. Calibration of such big systems can be a tedious task. This paper explains how fast and precise calibration procedures can be carried out automatically.

### Linearity and sensitivity error in the use of single strain gauges

This article describes the basic principles of strain measurement by means of strain gauges, from the strain itself via the variation in resistance to the eventual electrical signal, and compares the magnitude of error of the voltage-fed bridge circuit and the current-fed circuit.

## 6. Training, Webinars and References on Strain Measurements

### Recorded webinars

Missed one of our live webinars? Watch our recorded webinars on strain measurement and strain gauges. Use the filter to select the ones that best suits your needs.

### Success stories and case studies

Get access to all the success stories regarding the use of strain gauges in a wide scope of measurement applications and projects undertaken by HBM. Just select Strain Gauges in the dropdown list under Type of Sensors Used here.