Tension Testing Machine

Tension Testing Machine

 

a machine used to determine the mechanical properties of materials and to test machine parts, assembly units, and manufactured items by damaging or destroying them. A tension testing machine has a loading device and measuring instruments. Tension testing machines are classified according to their loading device as hydraulic or mechanical. The mechanical loading device can be lever-type, single-spindle, or multiple-spindle.

Tension testing machines with one or several constant strain rates are used to test elastic materials, such as metals, wood, rubber, polymers, and fabrics, while tension testing machines with a constant load rate are used to test brittle materials. Depending on the direction of their tensile force, tension testing machines are divided into vertical and horizontal types. The loading device, whether mechanical or hydraulic, applies repeated

Figure 1. Kinematic diagram of the R-5 universal tension testing machine: (1) electric motor, (2) power reduction unit, (3) cylindrical gears, (4) rotating screws, (5) nuts of movable platen, (6) movable platen, (7) fixed platen, (8) guide, (9) rack, (10) pinion of rack-and-pinion drive, (11) pulley, (12) cable, (13) stylus, (14) drum of tape-transport mechanism, (15) recording scale reducer, (16) shaft

cyclic loads. The measuring instruments record the forces and the strains at various stages of the tests. The force-measuring instruments may be mechanical—lever-type, lever-and-pendulum-type, or spring-operated—or hydraulic. The use of electronic circuits makes possible the automatic reproduction of a specific testing routine.

Tension testing machines designed for testing materials at high or low temperatures are fitted with furnaces and cryostats.

Tension testing machines that can be used to test not only for elongation but also for compression, bending, creep, long-term strength, and relaxation are called universal tension testing machines. A kinematic diagram of the Soviet R-5 universal tension testing machine is presented in Figure 1. Universal tension testing machines have a recorder that graphs the process in “load-strain,” “load-time,” and “strain-time” coordinates. Strain is recorded by means of a moving clamp or an extensometer mounted on the specimen.

The maximum force of the loading devices of tension testing machines is 105 newtons (N), or 104 kilograms-force (kgf), for nonmetals, 5 × 105N (5 × 104kgf) for metals, and more than 3 × 107N(3 × 106kgf) for manufactured items. The error in the readings of the force-measuring instruments is ± 1 percent, and the error of the recorder is ± 2 percent.

References in periodicals archive ?
For testing convenience, 6- and 12-inch-wide specimens were tested using a tension testing machine originally designed for lumber specimens.
In order to meet the time-to-failure requirements of ASTM D3500-90 (ASTM 2005c), the loading rates of the large panels tested on the floor fixture were 10 times that of the narrow panels tested in the tension testing machine.
Panels of widths 48, 36, and 24 inches were bolted into a fixture and tested on a reaction floor, while specimens of widths 12 and 6 inches were tested in an existing tension testing machine using hydraulic grips.
Tension testing of full-width OSB panels is problematic; hence, testing 6-inch widths is the benchmark for developing tension design values and quality control because commonly available lumber tension testing machines can be used.
Instrumentation: Creep/stress rupture testing machines, universal tension testing machines, pressure test systems, fatigue testers, furnaces and ovens for testing and processing, elastomeric extensometers, and special test equipment
Box 1529 Butler, PA 16003 Phone: (412) 283-1212 Instrumentation: Creep/stress rupture testing machines, universal tension testing machines, pressure test systems, fatigue testers, furnaces and ovens for testing and processing, elastomeric extensometers, and special test equipment Services offered: Technical service