Toughness sudden impact

The quality known as toughness describes the way a material reacts under sudden impacts. It is defined as the work required to deform one cubic inch of metal until it fractures. Toughness is measured by the Charpy test or the Izod test. 

The ability of a polymer to resist fracture when exposed to a sudden impact is the basis of tests for impact strength. These are loosely related to the toughness of the polymer, and fall into two main categories those suited for film and those suited for sheet. 

Impact Strength or Impact Resistance - Impact strength or Impact Resistance is the resistance of a material to fracture under a sudden impact, or shock force. It is a measure of the toughness of the material. 

Another basic physical property has to due with the concept of toughness. In engineering terms, the toughness of a material is its ability to withstand sudden impact (Figure 3.5). 

Figure 3.5 Toughness is the ability to withstand sudden impact. JohnTTakai/ Shutterstock.com.

As a result, quantifying the toughness of a given material in a given application is a highly subjective assessment. Sometimes the toughness of a material is evaluated based on structural failure as the result of sudden impact, by looking at the loads and structural deformations when a... 

Impact strength It is a measure of toughness, that is, how well a sample will withstand the sudden onset of stress, like a hammer blow. Usually, chain stiffening lowers the impact strength and increases embrittlement. 

Pure COP and partially crystalline blends with less than 80 mass% PC are rather brittle and show a consistently low impact resistance. Blends of this composition consist of a PC phase partially miscible with COP (Figure 9.25). The change in morphology is responsible for the sudden improvement of the impact resistance qualities in blends with more than 80 mass% PC. These particular products are almost amorphous and consist of dispersed COP spheres embedded in a tough PC matrix. The morphological and mechanical studies on COP + PC blends demonstrate the strong influence of sample preparation and blend... 

ABS is a thermoplastic which is tough and durable. Because it has high impact strength, it has applications where sudden loads may occur. 

Toughness can be difficult to quantify. How sudden is sudden As described earlier, all thermoplastics are rate sensitive, so the measured value of an impact at one rate will be distinctly different than the value of an impact at another rate. Then there is the question of the kind of impact. Is it a shear load A tensile load A compressive load A... 

Consider a polybutylene terephthalate (PBT) polymer for an impact situation in which both toughness and stiffness are important. Assume a cantilever beam loaded by a mass M at the end under suddenly applied loads. How much can the size (width b) be reduced by adding glass reinforcement How much can the weight of the beam be reduced with the reinforced PBT Use the data in Table 5.9. 

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