Tensile testing procedure

In a later publication [11], Pietsch et al. described a new apparatus designed to overcome the weaknesses of the earlier tensile testing procedure. Agglomerates were formed from powder with the desired moisture level in a ring-shaped cavity by compaction at about 70 kg/cm2 (990 lb/in.2). The agglomerate while still in the die was pulled apart to measure its tensile strength. 

The decision for this conversion will no doubt have a major impact on material suppliers, molders, designers, and end users whoi most of the material and product information accumulated for decades and still in use was obtained using ASTM procedures [75]. The current investigation is part of our effort in assisting this trattsition. The tensile properties of thermoplastics were analyzed not only for the purpose of comparing the ASTM and ISO tensile test procedures, but also for the importance of these properties in the product design. 

Mechanical Properties. The performance of various polyester resin compositions can be distinguished by comparing the mechanical properties of thin castings (3 mm) of the neat resin defined in ASTM testing procedures (15). This technique is used widely to characterize subtle changes in flexural, tensile, and compressive properties that are generally overshadowed in highly filled or reinforced laminates. 

Methods used for the tensile testing of single fibers and fibers taken from yams and tows are discussed in ASTM D3822 and D2101. Measurement equipment used in fiber tensile testing is described in ASTM D76. An overview of test procedures and their significance is also available (3,10). 

The measurement of mechanical properties is a major part of the domain of characterisation. The tensile test is the key procedure, and this in turn is linked with the various tests to measure fracture toughness... crudely speaking, the capacity to withstand the weakening effects of defects. Elaborate test procedures have been developed to examine resistance to high-speed impact of projectiles, a property of civil (birdstrike on aircraft) as well as military importance. Another kind of lest is needed to measure the elastic moduli in different directions of an anisotropic crystal this is, for instance, vital for the proper exploitation of quartz crystal slices in quartz watches. 

Cleaning the Wires and Fittings. Different types of resin with different characteristics require varying degrees of cleanliness. The following cleaning procedure was used for one type of polyester resin with which over 800 tensile tests were made on ropes in sizes -J- in. (6.5 mm) to 3- -in. (90 mm) diameter without experiencing any failure in the resin socket attachment. 

These test procedures and standards are subject to change, so it is essential to keep up to date if one has to comply with them. It may be possible to obtain the latest issue on a specific test (such as a simple tensile test or a molecular weight test) by contacting the organization that issued it. For example, the ASTM issues new annual standards that include all changes. Their Annual Books of ASTM Standards contain more than seven thousand standards published in sixty-six volumes that include different materials and products. There are four volumes specifically on plastics 08.01-Plastics 1 08.02-Plastics 11 08.03-Plastics III, and 08.04-Plastic Pipe and Building Products. Other volumes include information on plastics and RPs. The complete ASTM index are listed under different categories for the different products, types of tests (by environment, chemical resistance, etc.), statistical analyses of different test data, and so on (56,128,129). 

The most common test used to study the oxidation resistance of mbber compounds involves the accelerated aging of tensile dumbbell samples in an oxygen-containing atmosphere. Brown et al. [22] recently reviewed long-term and accelerated aging test procedures. The ASTM practices (D 454 (09.01) D 865 (09.01) D 2000 (09.01, 09.02) D3137 (09.01) D 572 (09.01) D 3676 (09.02) D 380 (09.02)) for these tests clearly state that they are accelerated tests and should be used for relative comparisons of various compounds and that the tests may not correlate to actual long-term... 

Stress-Strain Data. Tensile tests were made with an Instron tester at some seven crosshead speeds from 0.02 to 20 inches per minute at five or six temperatures from 30° to —46°C. The tests were made on rings cut with a special rotary cutter from the circular sheets of the elastomers. The dimensions of each ring were determined from the weights of the ring and the disc from its center, the thickness of the ring, accurately measured, and the density of the rubber. Typically, the outside and inside diameters were 1.45 and 1.25 inches, respectively, and the thickness was about 0.085 inch. The test procedure used is described elsewhere (11), and the cubic equation, eq 4 in ref. j 2, was used to compute the average strain in a ring from the crosshead displacement. 

The assessment of the rate of degradation follows a classic Arrhenius procedure. Yarns or specimens of film are exposed to water and steam at temperatures typically between 70 °C and 130 °C, followed by tensile testing and molecular weight determination, and the results are extrapolated to service temperatures [32]. There are however a number of uncertainties. Firstly, will steam above 100 °C and water below 100 °C have the same effect There appears to be a change in gradient at 90 °C extrapolation using all the... 

Tensile Testing. Tensile tests were run on an Instron 1000 using a 5.08 cm (2 Inch) guage length and a speed of 12.7 cm (5 lnches)/mln. The procedures In Burlington Test Procedure FP-015 (ASTM-D-579) were followed. At least 5 specimens of each sample were tested. Fabric tests results are quoted for the warp direction only. The percent retention of tensile strength was calculated from the equation % retention where F and F(j are the... 

Coating with Bulk Polybutadiene. E-glass fabric was embedded In Firestone s Diene 35 NFA using procedures very similar to those used to prepare peel test specimens. Rubber, which had been mill-mixed with 0.05% dlcumyl peroxide, was premolded between Mylar sheets to the desired thlckness(0.308, 0.151, or 0.100 cm) and size ( 30.5 X 18 cm) by molding for 1 hour at 60 C. and 40,000 lbs/5" ram. Fabric was cut so that the final size was at least one Inch smaller than the rubber sheets In all directions. A sandwich was made from the fabric and two premolded rubber sheets of the same thickness and about half the total thickness of the final sandwich. The sandwich was cured In a press for 2 hours at 150°C and 5000 lbs/5" ram. In the cured specimen the fabric was embedded In the center of the molded specimen (0.15 -0.40 In thick). Samples were Immensed In alkali before cutting to size for tensile tests. 

The [10°] off axis tension specimen shown in Fig 3.23 is another simple specimen similar in geometry to that of the [ 45 ]s tensile test. This test uses a unidirectional laminate with fibers oriented at 10° to the loading direction and the biaxial stress state (i.e. longitudinal, transverse and in-plane shear stresses on the 10° plane) occurs when it is subjected to a uniaxial tension. When this specimen fails under tension, the in-plane shear stress, which is almost uniform through the thickness, is near its critical value and gives the shear strength of the unidirectional fiber composites based on a procedure (Chamis and Sinclair, 1977) similar to the [ 45°]s tensile test. 

Swelling tests and determination of tensile properties. The procedure for estimating cross-link density from equilibrium swelling data is described in detail in a previous paper (6). The tensile properties of the PU films were carried out at 23°C and 60% relative humidity. The crosshead speed and distance were 10 mm/min and 30 mm, respectively. A more detailed description of the tensile tests is given elsewhere (6). 

A series of six stress-strain cycles with a crosshead rate of 600 mm/min was applied to specimens having a parallel length of 25 mm and a cross-section of 1 x 4 mm2 on a tensile testing machine. The samples were continuously stretched in six hysteresis cycles up to 60% of their elongation at break values, as shown in Fig. 47. This procedure is an established one and widely practiced for elastomeric composites reinforced with fillers such as carbon black and silica, which tend to build a strong filler-filler network [83]. 

The TS of the compacted samples was determined by transverse compression with a custom-built tensile tester. Tensile failure was observed for all the rectangular compacts when compressed between flat-faced platens at a speed ranging between 0.006 and 0.016 mm/sec. Platen speed was adjusted between materials to maintain a time constant of 15 2 seconds to account for viscoelastic differences the constant is the time between the sample break point and when the measured force equals Fbreak/e in the force versus time profile, where the denominator is the mathematical e. Specially modified punch and die sets permitted the formation of square compacts with a centrally located hole (0.11 cm diameter) that acted as a stress concentrator during tensile testing. This capability permitted the determination of a compromised compact TS and thus facilitated an assessment of the defect sensitivity of each compacted material. At least two replicate determinations were performed for each mechanical testing procedure and mean values are reported. 

The standardised test procedures are concerned with the resistance of the rubber to the liquid, not the estimation of degree of cure, and generally recommend the measurement of change in dimensions, tensile properties and... 

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