Resilience modulus

Elastic modulus, resilient modulus and flexural strength for design purpose... 

The allowable dimensional variation (the tolerance) of a polymer part can be larger than one made of metal - and specifying moulds with needlessly high tolerance raises costs greatly. This latitude is possible because of the low modulus the resilience of the components allows elastic deflections to accommodate misfitting parts. And the thermal expansion of polymers is almost ten times greater than metals there is no point in specifying dimensions to a tolerance which exceeds the thermal strains. 

Resilin and elastin have relatively high extensibility and resilience, but as compared to the collagen and the silks, the proteins sacrifice stiffness (elastic modulus) and strength (see Table 2). Collagen and dragUne sflk are much stiffer materials, but lack the extensibility that is characteristic of the rubber-like proteins. On the other hand, the mussel byssus fibers and the viscid silk have the extensibility of resilin and elastin, but lack the resilience [208]. 

The important elastic properties of a material undergoing deformation under static tension are stiffness, elastic strength and resilience. For a material obeying Hooke s law, the modulus of elasticity, E (= o/e), can be taken to be a measure of its stiffness. The elastic... 

It can be easily shown that equivalent expressions for the strain energy per unit volume are U=o e/2 and U = a2/2 E. The modulus of elastic resilience, Ur, of a material is defined as the strain energy absorbed per unit volume when it is stressed to its proportional limit. Thus,... 

The shaded area in the stress-strain plot shown in Figure 1.4 is numerically equal to the modulus of resilience. It is to be noted that for a given value of E, Ur directly proportional to cPL while for a given value of cPL, Ur is inversely proportional to E (stiffness). 

Asphalt concrete is properly proportioned to resist the potentially damaging effects in the road. Asphalt concrete paving mixtures should be evaluated for the following properties stability, flow, air voids, stripping resistance, resilient modulus, compacted density, and unit weight. Table 4.18 provides a list of standard laboratory tests that are presently used to evaluate the mix design or expected performance of fresh and hardened asphalt concrete. 

An instrument for measuring the mechanical properties of rubbers in relation to their use as materials for the absorption and isolation of vibration. These properties are resilience, modulus (static and dynamic), kinetic energy, creep and set. The introduction of an improved version has recently been announced. 

Additives and copolymers have extended the use of PET fibers into areas where the original commodity products had deficiencies, in, for example, soil-resistance, static protection or poor dyeability. Newer members of the polyester family have found applications in markets where more stretchiness or resiliency were desired (using longer aliphatic chains) or to gain higher modulus, temperature resistance and strength (with fully aromatic polymers). 

The physical properties of natural rubber and synthetic rubber compounds are affected greatly by the type and amount of fillers used. Carbon black is the most commonly used filler. Increasing amounts of carbon black increases the hardness and modulus of the vulcanizates. Resilience and resistance to impinging type abrasion decrease along with elongation. Tensile strength and tear strength... 

As the previous sections have shown, there are a large number of low temperature tests in existence. Even when ad hoc bending tests are disregarded, together with the use of the normal range of physical tests, such as tensile modulus and resilience, and the automation of a mechanical test by thermal analysis, there remain several types of specially developed low temperature tests. The various tests do not all have equal relevance to a given product. A test, or tests, should wherever possible, be chosen to provide the information most relevant to the particular application, but for many quality control purposes a test is used simply as a general indication of low temperature behaviour. Whatever the relative merits of the different methods in any situation, the question of correlation between the methods is frequently asked. 

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