04-01-2011, 06:18 PM
Modern Strain Measurement using Thin Polysilicon Strain Gauge
SEMINAR REPORT
Submitted by
VIKAS P
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
COLLEGE OF ENGINEERING
TRIVANDRUM
2010
SEMINAR REPORT
Submitted by
VIKAS P
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
COLLEGE OF ENGINEERING
TRIVANDRUM
2010
Modern Strain Measurement using Thin Polysilicon Strain Gauge.rar (Size: 949.63 KB / Downloads: 36)
ABSTRACT
The technology for measuring the strain is undergoing development at very high speed. The most commonly used strain gauge is metal foil/film strain gauges. Their large size and low sensitivity make accurate and precise strain measurement impossible. This paved the way for the development of Polysilicon Strain Gauge. The efficient performance of Polysilicon Strain Gauge is due to the glass frit bond backing. Unlike the other conventional strain gauges Thin Polysilicon Strain Gauges have improved Gauge Factor, Hysteresis, Nonlinearity and Temperature Coefficient of Resistance. The construction and principle of Thin Polysilicon Strain Gauge is also discussed.
Chapter 1
INTRODUCTION
Stress analysis is used to measure the distributions of stress in materials and structures that are subjected to static or dynamic loads. Such analyses commonly rely on strain techniques since stress can be calculated using Hooke’s Law. Hooke’s Law states that within the elastic limit, the stress is directly proportional to strain. The most widely used device to measure strain is a strain gauge. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. The gauge is attached to the object by a suitable adhesive, such as cyanoacrylate. This simple device has been used for many years
in all engineering fields and virtually all industries, including aerospace and
automobile industries. Even though wide variety of strain gauges are available, most commonly used strain gauge is electrical strain gauge, since they are characterized by relatively low cost, high level of accuracy, repeatability and reliability.
Chapter 2
STRAIN GAUGE
2.1 Overview
Strain Gauge is used to measure distributed strain in structures. The most widely used strain gauges are the electrical-resistance types, because they are characterised by a relatively low cost and a high level of accuracy, repeatability and reliability.
The operative principle of an electrical-resistance strain gauge has been known for more than a century. In general, a strain gauge is bonded onto the sensing element of the structure. The application of a load onto the sensing element causes a change in its shape, and a corresponding strain is applied to the strain gauge placed on the surface of the sensing element. The resistance of the strain gauge changes owing to the strain, and the degree of this change is used to calculate the magnitude of the load. The resistance variation is converted to voltage variation by Wheatstone bride configuration.