Charpy impact strength testing

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. 

Standard test methods for the determination of Charpy impact strength are listed in Table 12.11. For example, BS 2782 (method 351 A) uses a... 

Table 12.11. Standard test methods for the determination of Charpy impact strength...

B4 Charpy impact strength (unnotched) 50% of the value obtained on unprestrained. unexposed test pieces... 

Fig. 4.49 Influence of exposuring time in wash lye at 95 °C on Charpy impact strength of different polypropylene copolymers tested along flow direction [lOJae].

Izod Impact Strength and Charpy Impact Strength The standard tests for Izod impact strength are... 

Standard test methods for the determination of Charpy impact strength are Usted in Table 10.11. For example, BS 2782 (Method 351A) uses a rectangular, notched or unnotched, bar supported at both ends in such a position that the pendulum strikes it in the center, directly behind the notch. The energy absorbed in the impact is read directly by means of a pointer from a scale calibrated to allow for frictional and windage errors. Three standard test pieces are defined - the preferred being 120 x 15 x 10 mm with a span of 70 mm. The standard impact energies are 0.5, 1,4, 15, and 50 J. 

Compared to the rayrai composite the LyoceU reinforcement leads to a 30% increase in tensile modulus and to a shift in HDT to 134°C. These two values are the best in the whole series of tested composites. However, undesired effects are that the unnotched Charpy impact strength drops to one-half and the strength is reduced. 

Values and units The measured values of complete and hinged breaks can be used for a common mean value with remark. If in the case of partial breaks a value is required, it shall be assigned with the letter P. In case of nonbreaks, no figures are to be reported. (If within one sample the test specimens show different types of failures, the mean value for each failure type shall be reported.) Unnotched Charpy impact strength (kJ/m ). ... 

Impact strength of the ferrocement is essential for such applications as boat hulls, container walls and ballistic panels. It was tested by several authors, e.g. Grabowski (1985), with drop hammers, Charpy hammers and air gun projectiles. The results of comparative tests are expressed in crater depth or perforation characteristics and failure energy. The failure energy increases linearly with the wall depth and specific surface of the reinforcement. In Figure 3.4 tensile strength and Charpy impact strength are compared as functions of the specific surface of reinforcement. 

The Charpy impact strength values for all the investigated blends are shown as a function of the testing temperature in Fig. 24. The PBT homopolymer is taken as referenee material in order to evaluate the impact performance of the blends. 

Charpy Impact Test. This test is conducted in a very similar manner to the Izod impact strength test. The only difference is the positioning of the specimen. Figure 2-41 illustrates one such setup. In this test the specimen is mounted horizontally and supported undamped at both ends. Only the specimens that break com-... 

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. 

IS Charp Unnotched Charpy Impact Strength. The Charpy impact test uses a rectangular bar which is struck by a pendulum or hammer (or tup). The value obtained is given as the energy required to break a specified area of material, in kJ/mm. Specimen preparation is similar to that used for the Izod test although the test itself is markedly different to the Izod test as both ends of the sample are undamped. 

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