Instron Material Tester

Both destructive and nondestructive measurements can be done on an Instron Material Tester. In this system, the sample is loaded in a test cell, and the compression or tension force is measured when the upper part of the cell is moved over a given distance (time). Within the elastic limit of the gel, the elastic modulus E (or gel strength) is obtained from the initial slope of the nondestructive stress/strain curve additional deformation results in the breakage of the sample, giving the characteristic parameters—yield stress and breaking strain. 

The labor-intensive nature of polymer tensile and flexure tests makes them logical candidates for automation. We have developed a fully automated instrument for performing these tests on rigid materials. The instrument is comprised of an Instron universal tester, a Zymark laboratory robot, a Digital Equipment Corporation minicomputer, and custom-made accessories to manipulate the specimens and measure their dimensions automatically. Our system allows us to determine the tensile or flexural properties of over one hundred specimens without human intervention, and it has significantly improved the productivity of our laboratory. This paper describes the structure and performance of our system, and it compares the relative costs of manual versus automated testing. 

Mechanical Testing. Tensile strength tests were performed with an Instron tensile tester as per the American Society for Testing and Materials (ASTM) D-1682, and tear testing was done with an Elmendorf apparatus as per ASTM D-1424 at 21 °C and 65% rh, after conditioning the specimens for at least 24 h. Results reported are the average of three tests. 

Instron tensile tester n. A high precision electronic test instrument designed for testing a variety of material under a broad range of test conditions. It is used to measure and chart the load-elongation properties of fibers, yarns, fabrics, webbings, plastics, films, rubber, leather, paper, etc. It may also be used to measure such properties as tear resistance and resistance to compression. 

The experimental setup for the strain and elecfiical resistance measurements used simultaneously an Instron Universal Material Tester 4466 and a Keithley Multimeter. The researchers adopted a cycle test with a crosshead speed to a given maximum strain. 

Mechanical Properties. Mechanical properties obtained on the cured resins included tensile strength and fracture toughness. Tensile tests were run on an Instron model 1122 Universal Tester with a crosshead speed of 0.02 /minute. Tests were run on dry and saturated samples in air. Fracture toughness (K ) values have been obtained using a MTS 610 Materials Testing System at 0.02 /minute at ambient and elevated temperatures in air. The compact tensile specimens tested were 0.5 x 0.5 x 0.125 in dimension. Mechanical properties data are based on the results from four or more tests run at each condition. 

Instron tester Instron testers measure the flexural, tensile, and compressive strength of plastics as well as the stress-strain curves at ambient temperatures. They are commonly found in most materials testing laboratories. Instron testers come in a range of sizes (generally related to the maximum tensile pull that can be exerted) and types. They are manufactured by the Instron Machine Company. 

The SWNT ropes used were the same as those used for bundle strength measurements discussed earlier. The matrix material used was Epicote 1006 epoxy resin, a room temperature curing system. 32 dog-bone SWNT/epoxy specimens with dimensions of 40 mm x 3.5 mm x 0.4-0.6mm were obtained. The gauge length of die specimens was about 15 mm, and the length of SWNT ropes embedded in the epoxy was about 20 mm. Details of the fabrication method can be foimd elsewhere. The volume fraction of SWNT ropes in the composite was controlled widiin die range of 0.1-0.9%. Specimens were cyclically tested by an Instron 8800 Microforce Tester under tension-tension at 5 Hz, using a sinusoidal wave function at R ratio (ratio of minimum to maximum cyclic stress) of 0.1. 

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