Testing machines

Fatigue tests were performed under load control mode on a Schenck horizontal fatigue testing machine with hydraulic grips and a maximum load capacity of 25 kN. Tension-tension constant amplitude fatigue tests were carried out at three stress levels 60% a , 70% Cu and 80% a at two different stress ratios R = 0.1 and R = 0.5. The test frequency was kept constant (f = 3 Hz) for all the tests. 

Fig. 2. Illustrations of forces to which adhesive bonds are subjected, (a) A standard lap shear specimen where the black area shows the adhesive. The adherends are usually 25 mm wide and the lap area is 312.5 mm. The arrows show the direction of the normal apphcation of load, (b) A peel test where the loading configuration, shown by the arrows, is for a 180° peel test, (c) A double cantilever beam test specimen used in the evaluation of the resistance to crack propagation of an adhesive. The normal application of load is shown by the arrows. This load is appHed by a tensile testing machine or other...

The principal type of shear test specimen used in the industry, the lap shear specimen, is 2.54 cm wide and has a 3.23-cm overlap bonded by the adhesive. Adherends are chosen according to the industry aluminum for aerospace, steel for automotive, and wood for constmction appHcations. Adhesive joints made in this fashion are tested to failure in a tensile testing machine. The temperature of test, as weU as the rate of extension, are specified. Results are presented in units of pressure, where the area of the adhesive bond is considered to be the area over which the force is appHed. Although the 3.23-cm ... 

Peel tests are accompHshed using many different geometries. In the simplest peel test, the T-peel test, the adherends are identical in size, shape, and thickness. Adherends are attached at thek ends to a tensile testing machine and then separated in a "T" fashion. The temperature of the test, as well as the rate of adherend separation, is specified. The force requked to open the adhesive bond is measured and the results are reported in terms of newtons per meter (pounds per inch, ppi). There are many other peel test configurations, each dependent upon the adhesive appHcation. Such tests are well described in the ASTM hterature. 

Test pieces for Brinell testing must have two parallel sides and be reasonably smooth for proper support on the anvil of the test machine. Minimum sample thickness must be 10 times indentation depth. Successive indentations must not be closer than three indentation diameters to one another or to the edge of the test piece. 

The Rockwed testing machine is thus a framework permitting stable support of the workpiece on one side and means to impress the indenter under specified load on the other. A dial indicator attached to the indenter spindle is used to read directly the depth of indentation in hardness numbers. 

The Rockwell superficial test was developed to accommodate smaller and thinner samples than the standard Rockwell test. The test principle is identical to the standard Rockwell test but the major and minor loads are substantially smaller. The test machine is also similar but modified to accommodate the smaller loads. Dual purpose machines can handle both standard and superficial tests. 

Fig. 4. Opera ting principles of various laboratory lubricant-test machines.

Years of development have led to a standardized system for objective evaluation of fabric hand (129). This, the Kawabata evaluation system (KES), consists of four basic testing machines a tensile and shear tester, a bending tester, a compression tester, and a surface tester for measuring friction and surface roughness. To complete the evaluation, fabric weight and thickness are determined. The measurements result in 16 different hand parameters or characteristic values, which have been correlated to appraisals of fabric hand by panels of experts (121). Translation formulas have also been developed based on required levels of each hand property for specific end uses (129). The properties include stiffness, smoothness, and fullness levels as well as the total hand value. In more recent years, abundant research has been documented concerning hand assessment (130—133). 

Slides Slab and sheet metal rolling extrusion, etc., of polymers tensile-testing machines hardness-testing machines hardness indentations. 

Minimum allowable test Machine Reynolds number is 180,000 Minimum allowable test Machine Reynolds number is 90,000... 

While detail may be found in the ASTM D-3330 or PSTC-1 and PSTC-2 standards, the peel test is typically carried out as follows The tape is conditioned at 23°C and 50% relative humidity for 1 day. Next, the tape is rolled down with a weighted standard roller onto a clean test substrate (usually polished 302 stainless steel), allowed to dwell for a specified time (usually 1 min), and then clamped with the testing fixture in the test machine and peeled at a specified rate. 

Tensile testing machine operated in a controlled temperature and humidity environment. Many applications involve bonding paper, which exhibits properties that are highly dependent on humidity. In addition, adhesive Tg values are often close to room temperature, and thus properties change substantially over even a few degrees. Therefore, for reproducible comparisons, temperature and humidity control is necessary. 

Tensile and flexural properties were studied with an Instron 4204 testing machine. Tensile tests were performed on the drawn strands at a test speed of 3 mm/ min, while three-point-bending tests (ISO 178) at a speed of 5 mm/min were applied to the injection molded specimens. Charpy impact strength was measured of the unnotched samples with a Zwick 5102 pendulum-type testing machine using a span of 70 mm. The specimens (4 X 10 X 112 mm) used for three-point-bending tests were also used for the impact tests. It should be noted that neither the tensile tests for the strands nor the impact tests were standard tests. The samples were conditioned for 88 h at 23°C (50% r.h,) before testing. 

Load Testing Apparatus. The load apparatus used to simulate the working load on the test unit shall be calibrated in accordance with ASTM E-4 Standard Methods of Verification of Testing Machines, so as to assure that the prescribed test load is obtained. 

Tensile Requirements of Individual Wire. Specimens shall not be less than 18 in. (457 mm) long, and the distance between the grips of the testing machine shall not be less than 12 in. (305 mm). The speed of the movable head of the testing machine, under no load, shall not exceed 1 in./min (0.4 mm/s). Any specimen breaking within - in. (6.35 mm) from the jaws shall be disregarded and a retest made. 

Note The diameter of wire can more easily and accurately be determined by placing the wire specimen in the test machine and applying a load not over 25% of the breaking strength of the wire. 

When the distance between the jaws of the testing machine is less than 8 in. (203 mm), the minimum torsions shall be reduced in direct proportion to the change in jaw spacing, or determined by... 

L = distance between testing-machine jaws for short wire in in. (mm)... 

The shocks that measuring devices are subjected to are. generally cliaracterized by art acceleration (or deceleration), and a time span. For example, a device is said to withstand 500 g (5,000 m/s ) for lb ms. This refers to a half-sine. Shock testing machines produce a deceleration impulse having the form shown in Figure 4. 2.S7..., , , ... 

In the compression test, four or five sample cubes of the slurry are allowed to cure for a specified period of time. The cement cubes are placed in a compression testing machine and the compressive strength of each sample cube obtained experimentally. The average value of the samples is obtained and reported as the compressive strength of the set cement. 

When formulating a system for optimum abrasion resistance, both the epoxy/resin hardener binder system and the filler blends used appear to have an influence. The simulation of abrasive service loads on industrial floor toppings in a laboratory is not simple, and numerous wear test machines have been devised. Correlation between different wear test machines is not always good, although most... 

Fig. 8.101 Bend lest using a tensile testing machine (after Beck et al. )...

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