Elastic material

Fig. 26.7. Skidding on a rough road surface deforms the tyre material elastically.

The storage modulus is proportional to the amount of energy which is stored in the material elastically, whereas the loss modulus corresponds to the energy that is dissipated during one load cycle. Both quantities are combined in the damping factor tan 8 which is defined as... 

The chief problem is that plastic deformation effects at the crack tip usually obscure the process of surface formation. The work needed to propagate a crack is utilized not only to form two surfaces and to bend the cleaved material elastically but also for plastic deformation around the crack tip [16]. The energy needed for this plastic deformation is dissipated as heat. Hence the measured quantity, which is called the effective fracture surface tension yntts- is numerically larger than y. Reliable results can only be obtained at temperatures below 150 K when plasticity practically disappears 121,55]. 

In addition to zero-shear viscosity, material elasticity plays an important role in determining coalescence behavior in the rotational molding process.For rotational molding grade material, this effect was first recognized from the experimental results obtained with impact modified polypropylenes and is illustrated in Fig. In this work, the relative elasticity of resins... 

Fiber jet speed and material elasticity are two of the most important parameters involved in the jet-mandrel interaction and each of these properties are influenced by multiple electrospinning parameters, such as solution conductivity, viscosity, voltage, and feed rate. In addition, material properties cannot be accurately predicted without knowing the exact degree of solvent evaporation at the point when fibers are taken up by the collector. 

The following deliberations help matters further. In the description of the flow behavior of viscous and viscoelastic materials, elastic, viscous and inertial forces... 

Workplace exposure to PCBs can occur during repair and maintenance of PCB transformers accidents, fires, or spills involving PCB transformers and older computers and instruments and disposal of PCB materials. In addition to older electrical instruments and fluorescent lights that contain PCB-filled capacitors, caulking materials, elastic sealants, and heat insulation have also been known to contain PCBs. Contact with PCBs at hazardous waste sites can happen when workers breathe air and touch soil containing PCBs. Exposure in the contaminated workplace... 

Material Elastic modulus (GPa) Yield strength (MPa) Tensile strength (MPa) Fracture toughness (MPa m1 2)... 

Elastomers constitute a third class of polymers. Similarly to thermosets, elastomers have a network structure formed by crosslinking between the polymer chains. However, the number of links is less than in the case of thermosets which gives these materials elastic properties. Elastomers can be deformed by the application of external forces. When these forces are suppressed, the polymer recovers its original form. From a commercial point... 

R. Houwink, Elastizitat, Plastizitat und Struktur der Materie [Elasticity, Plasticity and Structure of Materials], Dresden and Leipzig, 1938, p. 353. 

Unlike elastic deformation in which the atoms maintain their nearest neighbors, flow involves changes in nearest neighbors and is a process of shear. This process is also dependent on time, so that one is concerned with the change of strain with time. The ease of flow in a liquid is characterized by its viscosity. Viscous flow is usually associated with liquids but it can occur in amorphous solids. For such materials, elastic and viscous processes can coexist. This is termed viscoelasticity and one can view elastic and viscous deformation as the limiting conditions of such behavior. Flow processes, such as creep, can also occur in crystalline materials. In this situation, the deformation processes involve different mechanisms but they can mimic viscoelastic behavior. 

Material Elastic Modulus (GPa) Thermal Expansion Coefficient Fracture Strength (MPa) Density (g/cm ) Softening point ec)... 

As a hardening material, elasticity modulus of concrete increases as age grows, therefore, the elasticity modulus of concrete and mortar are function related with time. Elasticity modulus of concrete and mortar are usually expressed by Eq. 7 (Bofang Zhu. 1999). If the elasticity modulus of concrete and mortar are given, and the effect of interface is not considered, Eq. 1 and 2 can be utilized to determine the concrete equivalent elastic modulus. For this calculation, concrete age should be discretized firstly, and then the equivalent elastic modulus for each increment of time can be obtained. 

Table 1. The effects of a change in the material elastic modulus on the structure s maximum internal forces during an earthquake in the direction along the main girder.

THE EFFECT OF A CHANGE IN THE MATERIAL ELASTIC MODULUS ON THE EARTHQUAKE RESPONSE IN THE DIRECTION ALONG THE MAIN GIRDER... 

The plate stiffness parameter a and stress concentration parameters Px and Py depend on the plate geometry a/b, edge and loading conditions, and material elastic constants Ex, Ey, Gxy and Vxy. 

Material Elastic modulus GPa Tensile strength MPa Density g cm" Specific stiffness MJ kg- specific strength MJ kg- Reference... 

---