Toughness drop testing

Figure 2. Typical Load-Displacement (left) and Potential-Drop-Crack-Length-Measurement (right) Records Acquired During Fracture Toughness Test of Forged Stainless Steel.

Overall, impact strength tests are measures of toughness or the ability of a sample to withstand sharp blows, such as being dropped. 

Profusion of branching should be proportional to number of rubber particles greater in size than the minimum discussed above. At a given rubber content, the number of rubber particles varies as the reciprocal of the third power of particle diameter. Thus, number of particles drops rapidly as particle size climbs above the effective minimum. Laboratory tests show that stiffness properties depend on total rubber content irrespective of particle size (provided the specimen dimensions are large compared with particle dimensions) hence, narrow particle size distribution is essential if maximum toughness is to be combined with minimum loss in stiffness properties (modulus, creep). 

The flaw spectrum approach may be capable also of correlating failure data obtained under conditions which appear to give different material behavior. For example, tensile, Izod, and dart drop impact tests all give different impact energies or toughness measures. In part, this may be explained by the simple idea that a different fraction of flaws is active in each test. Equal biaxial loading (as in dart drop) and uniaxial tension (as in tensile impact) give rise to different flaw activities thus it is to be expected that the number of crazes produced in each test will be different. 

Numerous studies have been made of the mechanical properties of fibrous composites these include recently published papers on impact properties by Izod (1,2, 3,4) and Charpy (5,6) and drop weight (7) tests. We reported the Charpy impact fracture behavior of various glass-polyester composites regarding the effects of temperature (8,9,10), specimen size (8), and fiber orientation (10). This paper describes the effects of the tough-brittle transition in the impact behavior of glass-polyester composites which occurs with a variation of temperature and specimen size. 

For conditions of constant craze thickening rate, agreement between prediction and experiment is already very encouraging, particularly at higher speeds. There are still refinements to be made to the experimental method, and drop-weight striker speeds of less than 0.5 m/s will remain inherently difficult to control. Nevertheless, the Full Notch Impact test provides a promising direct method for the measurement of cohesive properties in tough polymers. 

A DROP TOWER METHOD FOR HIGH RATE FRACTURE TOUGHNESS TESTING... 

Dynamic properties, fracture toughness, fracture energy, dynamic modulus, dynamic testing, impact tests, drop tower, high strain rate. 

A Drop Tower Method for High Mte Fracture Toughness Testing of Polymers... 

A drop tower has been shown to be capable of performing high rate SENB tests and the associated tests such as elastic modulus and contact stiffness. Fracture toughness was assessed... 

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