Material properties strength

Properties. Properties of stmctural siHcon nitride ceramics are given in Table 2. These values represent available, weU-tested materials. However, test methodology and the quaHty of the specimens, particularly their surface finish, can affect the measured values. Another important material property is tensile strength. Values obtained on Norton s NT154 material are 750 MPa at RT, 500 MPa at 1200°C, and 350 MPa (50,000 psi) at 1400°C (62). 

Because shear and compressive strengths s andp depend in a similar way on material properties such as lattice stmcture and bond strength,yis often in a rather narrow range of about 0.20—0.35 for a wide variety of materials. The following are typical data for sliding on steel with bearing materials varying several hundredfold in yield pressure ... 

Copolymers extend the number and range of available materials, enabling the polymer scientist to achieve combinations of material properties (eg, tensile strength, solubiHty, solvent resistance, low temperature flexibiHty, etc) unattainable from the simple constituent homopolymers. As a result, a large number of copolymers have become commercially important. Table 1 Hsts some of them. 

Engineering design, then, involves many considerations (Fig. 1.7). The choice of a material must meet certain criteria on bulk and surface properties (strength and corrosion resistance, for example). But it must also be easy to fabricate it must appeal to potential consumers and it must compete economically with other alternative materials. In the next chapter we consider the economic aspects of this choice, returning in later chapters to a discussion of the other properties. 

Material properties for ice are listed in Table 28.3. The fracture toughness is low (0.12 MPa m ). The tensile strength of ice is simply the stress required to propagate a crack of dimensions equal to the grain size d, with... 

It has been argued that material properties sueh as the ultimate tensile strength have only positive values and so the Normal distribution eannot be the true distribution. 

There is no data available on the endurance strength in shear for the material chosen for the pin. An approximate method for determining the parameters of this material property for low carbon steels is given next. The pin steel for the approximate section size has the following Normal distribution parameters for the ultimate tensile strength, Su ... 

Plastic Material Introduced Strength Properties Acids Bases Agents... 

Electrical Properties Traditionally plastics have established themselves in applications which require electrical insulation. PlFt and polyethylene are among the best insulating materials available. The material properties which are particularly relevant to electrical insulation are dielectric strength, resistance and tracking. 

Throne has reported that the relationship between foam modulus and density can be generalised to other properties such as tensile strength, fatigue strength, creep properties as well as shear and compression modulus. Thus if X is the general material property then... 

Material Properties. Materials possess various mechanical and chemical properties, and, therefore, it is possible to select materials appropriate for severe corrosion conditions. For example, if the equipment is under cyclic loading, a material with high fatigue strength is desired. Similarly, it is desirable to have corrosion-resistant materials for the corrosive environments. There are several sources for obtaining information on materials properties. Some are listed in Table 4-173. 

Variations in material properties. Because no two plastic (or steel, for that matter) melts are exactly alike, some may have inclusions and so on, the strength properties given in materials tables are usually average values. If the value stated is a manufacturer s value, it probably is the minimum value, which can significantly reduce or eliminate its uncertainty. 

Also, it appears from the data that these metals are much stiffer and significantly stronger than the plastics. This approach to evaluation could eliminate the use of plastics in many potential applications, but in practice it is recognized by those familiar with the behavior of plastics that it is the stiffness and strength of the product that is important, not its material properties. 

To illustrate the correct approach, consider applications in which a material is used in sheet form, as in automotive body panels, and suppose that the service requirements are for stiffness and strength in flexure. First imagine four panels with identical dimensions that were manufactured from the four materials given in Table 3-1. Their flexural stiffnesses and strengths depend directly on the respective material s modulus and strength. All the other factors are shared in common with the other materials, there being no significantly different Poisson ratios. Thus, the relative panel properties are identical with the relative material properties illustrated in Fig. 3-3. Obviously, the metal panels will be stiffer and... 

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