The elastic deformation proportional to force can be measured by mechanical, optical, acoustical, pneumatic, and electrical means. The earliest strain gages were mechanical devices. However, mechanical devices tend to provide low resolutions, are bulky and difficult to use. Optical sensors are sensitive and accurate, but delicate and operate best under laboratory conditions.
Although capacitance and inductance-based strain gages have been constructed, these devices sensitivity to vibration, their mounting requirements, and circuit complexity have limited their application. The photoelectric gages are also costly and delicate.
The most widely used characteristic that varies in proportion to strain is electrical resistance.
Wed, 2010-09-01 13:55
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