Pendulum impact tests

The pendulum impact test employs a pendulum type of hammer. It is carried out in four ways Izod, Charpy, Chip and Tensile. The apparatus used for the pendulum test consists of a heavy base with a vice for clamping the specimen and a pendulum hammer swinging at a sample. The machine base must be kept on a rigid platform to prevent vibrational energy losses. 

The chip impact test is carried out in a similar way to the Izod test but without a notch. The test specimen is usually 25.4 mm long, 12.7 mm wide, and 1.65 mm thick. The tests are carried out using ASTM D4508 [79]. Because the test involves an un-notched sample, it reflects material toughness rather than the notch sensitivity measured for the Izod and Charpy tests. 

The tensile impact test is carried for un-notched samples in a test setup where one end of the specimen is mounted in the pendulum and other end is gripped by a crosshead member which travels with the pendulum until the instant of impact. The tensile force is exerted by the pendulum. The advantage of the tensile impact test over Izod or Charpy tests is that thinner and ductile samples can also be tested by the tensile impact test, whereas Charpy/Izod tests are limited to only thicker and rigid samples. 

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Pendimethalin, 73 319 Pendulum impact tests, 19 580 Penetrating particle size, in depth filtration theory, 11 340-341... 

Fatigue resistance increases with the [PU] up to 50Z, while energy absorption determined from dynamic properties and pendulum impact tests varies directly with the [PU], The micromechanism of failure Involves the generation of discontinuous growth bands associated with shear yielding rather than crazing. 

FIGURE 14.16 Pictorial description of Charpy (a) and Izod (b) pendulum impact tests. 

Figure 8.13 Dependence of two estimates on the impact strength on the amount of PDMS in PDMS-modified Si02 glasses.144 The impact strengths were obtained from (O) the Charpy pendulum impact test (A) the falling-weight impact test.

While the products have single and broad glass transitions, the SINs prepared by the prepolymer procedure show slightly broader transitions than those by the one-shot procedure. The percent energy absorption determined from dynamic properties and pendulum impact tests increases directly with PU content for both series. However, the values from the prepolymer procedure are always larger than those obtained from the one-shot procedure. 

The desired energy to rupture the test piece is then simply the dilTcrencc between the uncorrected energy read from the maximum swing of the pendulum after impact and the above correction energy. As for the Charpy and Izod tests, the result is normalized with respect to the area of the test piece cross section, although unlike the other pendulum impact tests, there arc several types of test piece that are used. Fig. 16 illustrating these. 

Figure 11-19. Schematic representation of different types of flexural tests. I, Flexural test with sample supported at two points II, flexural text, sample clamped at one point III, pendulum impact test to determine the flexural impact strength IV, flexural impact test V, tensile impact test.

ISO 13802 Plastics - Verification of pendulum impact-testing machines - Charpy, Izod and... 

A type of pendulum impact test in which a notched sample bar is held at one end and broken by a blow. This is a test for shock loading. 

JSA (2005) Method for Charpy Pendulum Impact Test of Metallic Materials, JIS Z 2242, Japanese Standards Association, Tokyo. 

ISO (2009), Metallic materials - Charpy pendulum impact test - Part 1 Test method, ISO 148-1 2009, International Organization for Standardization, Geneva. 

A free-falling dart method for polyethylene films is described in ASTM D1709. Unlike low-speed uniaxial tensile tests, the pendulum impact test measures the resistance of film to impact puncture, simulating high-speed end use application. Dart drop measures the energy lost by a moderate velocity blunt impact passing through... 

Figure 9.17 Charpy (supported-beam) pendulum-impact test. View from above the specimen.

Typically in the United States, bumpers—front and rear—are expected to adhere to the standard 49 CFR Part 581 set by the National Highway Traffic Safety Administration [8]. As per this standard, passenger cars are subjected to barrier tests at vehicular speeds of 2.5 mph on full bumper width, followed by subsequent pendulum impact tests at vehicular speeds of 1.5 mph on full width and comers, with the pendulum impacting the vehicle at heights of 16-20 inches [8,9]. Bumpers are expected to withstand such... 

The deterioration of mechanical properties is normally assessed by measurements of fracture resistance by pendulum impact test methods or slow speed flexural strength measurements and by ensuring that the surface of the specimens subjected to tensile stresses corresponds to the face exposed to the UV (or weathering) source. These tests are generally more meaningful than nondestructive tests, such as modulus measurements, since the chemical changes and the creation of fine cracks (often invisible to the naked eye) may involve only a very fine layer on the surface of the exposed samples. 

Tensile Impact Test (ASTM D1822). The tensile impact strength test was developed to overcome the deficiencies of flexural (Izod and Charpy) impact tests. The test variables, such as notch sensitivity, toss factor, and specimen thickness, are eliminated in the tensile impact test. Unlike Izod-Charpy-type pendulum impact tests, which are limited to thick specimens only, the tensile impact test allows the user to determine the impact strength of very thin and flexible specimens. Many other characteristics of polymeric materials, such as the anisotropy and the orientation effect, can be studied through the use of the tensile impact test. 

The biggest advantage of the falling-weight impact test over the pendulum impact test or high-rate tension test is its ability to duplicate the multidirectional impact stresses that a part would be subjected to in actual service. The other obvious advantage is the flexibility to use specimens of different sizes and shapes, including an actual part. Unlike the Izod impact test, which measures the notch... 

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