Influence of Mechanical Load

The influence of mechanical loading on conduit and holding structures is only partially understood. Increased intravascular pressure associated with hypertension leads to increased vessel wall diameters and thickness. This may be due to increased mechanotransduction by medial smooth muscle cells. 

The environmental stress cracking of a PBT/PBA copoly(ester ester) in water and phosphoric acid solution (pH = 1.6) at 80°C is demonstrated by comparing the combined influence of mechanical load and environment with the separate individual influences. The ESC in phosphoric acid is both physical and chemical. The physical component is dominant at relatively high loads of 6-7 MPa which corresponds with short failure times of up to 3 hours. The chemical component is dominant when the failure times are long because of lower loads. 

Effect of Mechanical Load. The influence of mechanical load on thermal conductivity of various evacuated multilayer insulations has been investigated. Figure 9 shows the effect of mechanical load on thermal conductivity for the above multilayer insulation. Assuming that the thermal conductivity of insulation under compression is a function of the heat transferred by solid conduction at the contact points, the thermal conductivity is a function of the size of the contact area. The size of the contact area is proportional to the f power of the contact pressure [ ]. The curve representing the f power of mechanical load has the same shape as the experimentally measured points for loads exceeding about 2 psi. 

Ta bl e 1.12 The influence of mechanical load on the change in strain at break relative to the initial value in polyamide 610 under thermal-oxidative exposure [70]... 

The influence of mechanical load during oven storage 130 °C on thermal-oxidative resistanoe in polypropylene (dynamic DSC-OIT) [71]... 

In addition to influences of mechanical load on degradation in polymer chains, unexpected degradation can occur due to the initiation of specific micromechanical processes and mechanisms. Such mechanisms (shear flow, craze formation, cavitation, etc.) are initiated in particular in inhomogeneous polymers (blends, filled and reinforced plastics, etc.) by inhomogeneous stress distributions caused by external mechanical loads. Typical examples for such physical aging processes are ABS materials with an unfavorable size distribution of rubber particles [72],... 

Influence of mechanical loading during injection molding [591]... 

In addition to the study of the structure of materials, the influence of several parameters on morphology can be studied, in particular the influence of mechanical loading. There are several methods to investigate deformation and fracture processes, which are discussed in detail in [1,2,5]. The direct imaging techniques of microscopy allow very direct determination of the morphology and... 

Lee, D. A., Noguchi, T, Frean, S. R, Lees, R, and Bader, D. L. 2000. The influence of mechanical loading on isolated chondrocytes seeded in agarose constructs. Biorheology, 37,149-161. 

This chapter is concerned with the influence of mechanical stress upon the chemical processes in solids. The most important properties to consider are elasticity and plasticity. We wish, for example, to understand how reaction kinetics and transport in crystalline systems respond to homogeneous or inhomogeneous elastic and plastic deformations [A.P. Chupakhin, et al. (1987)]. An example of such a process influenced by stress is the photoisomerization of a [Co(NH3)5N02]C12 crystal set under a (uniaxial) chemical load [E.V. Boldyreva, A. A. Sidelnikov (1987)]. The kinetics of the isomerization of the N02 group is noticeably different when the crystal is not stressed. An example of the influence of an inhomogeneous stress field on transport is the redistribution of solute atoms or point defects around dislocations created by plastic deformation. 

For a given material, there are generally several possible mechanisms of yielding and fracture, each characterized by the influence of temperature, loading rate, hydrostatic pressure, time (physical aging). A vast literature deals with the influence of network structure on yielding or on fracture properties, but we have to be very careful with the results obtained because of the different types of networks used in these experiments. 

The influence of mechanical parameters such as mean stress or ratio between minimum and maximum load on fatigue crack propagation has been investigated for... 

The influence of the load on the time to failure and the failure mechanism will be shown. The failure mechanisms are interpreted through SEM images of fracture surfaces. 

The measuring principle is based on an abrupt decoupling of the sensor driving circuitry from the resonator and monitoring the decay of the quartz sensor oscillation. Fig. 27. The influence of electrical load on the crystal is both minimized and independent of the mechanical load on the crystal. It is possible to measure the resonance frequency for parallel oscillation mode, /p, the resonance frequency for series oscillation mode,/s, the decay constant for parallel oscillation mode. Dp, and the decay constant for series oscillation mode, Ds. 

TABLE 1 Influence of SWNTs loading on mechanical properties of PANi-AMPSA fibers... 

TABLE 1 The influence of CNTS loading on mechanical properties before and after doping... 

Mechanical strains that continuously influence the cell responses have led cytomechanics to be a significant research area in both fundamental and translational research. Animal models have been used to understand the effect of mechanical loading on cell development in the tissues for many years. However, their variation in terms of age, size, and behavior may limit them as an accurate model in the assessment of tissue mechanobiology. Moreover, the cellular response to varying mechanical strains in the native tissue caimot be easily investigated due to the parallel contributions of other stimulating factors such as biochemical, topological, and other mechanical cues. 

Wang, R.H., Li, J.L., Jiang, Y, etal. 2010. Experimental research on influence of cyclic loading and unloading on rock mass residual strength. Chinese Journal of Rock Mechanics and Engineering 29( 0) 2103-2109. 

Figure 1.58 provides long-term characterization for plastics in engineering applications, considering the influences of mechanical and thermal load and media exposure during use that usually occur simultaneously. 

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