Tensile testing apparatus have three types:

1.Constant velocity elongation type (CRE) : the deformation rate per unit time of the specimen remains constant during the tensile process.

2.Parliamentary load type (CRL): the load increase rate of the test sample under stretching is basically constant.

3.Constant speed traction type (CRT) : when the sample is subjected to the lower clip traction, the upper clip has an irregular displacement according to the stress-strain characteristics of the material.

（1）The equal-speed traction type, which has a wide range of applications and is a mechanical type, is often called the pendulum type power machine. Multiple tensile properties can be tested with proper clamping device and automatic recording device. However, because the inertia of the pendulum and the strain rate per unit time vary with the stress-strain characteristics of the material, the precision of the instrument is low and the comparability is poor.

（2） The typical equiloading device is a beveling machine, which can be used to measure the tensile properties of fiber and yarn. Among them, the inclined plane strength machine combined with electromechanical can stretch and replace the pipe yarn automatically for 10 pipe yarn according to the specified test times continuously, and also can draw the curve diagram of breaking strength and breaking elongation. The instrument is equipped with data processing system, which can print test results directly.

（3）at the end of 1970s, an automatic single yarn strength meter with constant speed and elongation was developed. Strain sensor was used to measure the force. It can be divided into two types: general type and special type according to different capacity. The universal instrument can measure the tensile properties, elasticity and compressibility of fiber, yarn and fabric by changing sensors of different capacity. Shear, bending and friction tests may also be carried out with appropriate attachments. This kind of instrument is sometimes called universal strength tester, which can display the test results by digital, automatic data processing and printing. Some types of instruments are also equipped with high and low temperature test equipment. China's successful development of desktop is a special single fiber electronic tensile strength tester, instrument maximum capacity for 100 grams, digital display and automatic recording, some still can print out the averages and variation coefficient of tensile properties.

（4）In the 1980s, the automatic short fiber strength instrument was made. With tensile properties tester to test a variety of test results can be obtained, such as breaking strength, breaking elongation and the tensile fatigue, or elongation at specified load flexibility, as well as the fabric tear strength, bursting strength, sewing, etc. In addition, the initial modulus, fracture work and other indicators can be obtained by using the recorded drawing.

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