Stress-strain behavior mechanisms

The effect of temperature on PSF tensile stress—strain behavior is depicted in Figure 4. The resin continues to exhibit useful mechanical properties at temperatures up to 160°C under prolonged or repeated thermal exposure. PES and PPSF extend this temperature limit to about 180°C. The dependence of flexural moduli on temperature for polysulfones is shown in Figure 5 with comparison to other engineering thermoplastics. 

Harold S. Morgan and Robert M. Jones, Buckling of Rectangular Cross-Ply Laminated Plates with Nonlinear Stress-Strain Behavior, Journal of Applied Mechanics, September 1979, pp. 637-643. 

These differences on the stress-strain behavior of P7MB and PDTMB show the marked influence of the mesomorphic state on the mechanical properties of a polymer. When increasing the drawing temperatures and simultaneously decreasing the strain rate, PDTMB exhibits a behavior nearly elastomeric with relatively low modulus and high draw ratios. On the contrary, P7MB displays the mechanical behavior typical of a semicrystalline polymer. 

Hydrogen effect on the mechanical properties discussed below was studied on several a and a+fi alloys with the following nominal composition of metallic components (Russian trade marks given in parentheses) commercial titanium of nominal purity 99.3% (VTl-0), Ti-6Al-2Zr-1.5V-lMo (VT20), Ti-6A1-4.5V (VT6), Ti-6Al-2.5Mo-2Cr (VT3-1), Ti-4Al-1.5Mn (OT4), Ti-6.5Al-4Mo-2Sn-0.6W-0.2Si (VT25u) and others. The main features of their stress-strain behavior due to hydrogenation were much similar, but some individuality was characteristic of each alloy. 

LDPE affect the dynamic mechanical, as well as other material properties of these polymers. The similarity of the temperature dependence of E between our toluene cast HB film and the quenched LDPE (both of 40% crystallinity) in Figure 14A as compared to our quenched HB film (% crystallinity 30%) is another indication of the importance of the level of crystallinity on properties. (This topic has already been discussed in some length in the section on stress-strain behavior). 

FIGURE 14.9 Influence of temperature on the stress-strain behavior of a sample of poly(methyl methacrylate). (Modeled after Carswell, T.S. and Nason, H.K. Effects of Environmental Conditions on the Mechanical Properties of Organic Plastics, 1944. Copyright, ASTM, Philadelphia, PA. With permission.)... 

Mechanical data like stress/strain behavior, impact resistance in comparison to polystyrene... 

At the end of Section 5.4.2.5, the statement was made that most continuous, unidirectional fiber-reinforced composites are used to produce layers that are subsequently assembled to form laminate composites. In this section, we expound upon this statement by examining the mechanics of laminate composites, first through a generalized description of their mechanics, then with some specific stress-strain behavior. 

Some interesting results have already been obtained (JO, 11) on these polymers, where the effect of the above molecular parameters on the mechanical properties has been studied. Thus, Figure 11 shows the effect of variations in block length and styrene content on the stress-strain behavior of styrene-butadiene-styrene (SBS) polymers. As expected, the stress levels increase with increasing styrene ( filler ) content but are independent of the block lengths. In other words, the center block size does not exert the same influence as the molecular weight between cross-... 

Figure 11. Mechanical stress-strain behavior of four strips cut from a cell after a RH cycling test of 50 cycles from 0-100% RH the blue spots marked on the MEA are leaking locations identified by a bubble test after the RH cycling the insert shows the fracture location ofeach strip.

Figure 24. Mechanical decay of MEAs after endurance test at 1000 mA/cm2 the trend of reduction of membrane ductility is shown on the left figure and the stress-strain behavior of the sample tested for 820 h and the control is shown on the right figure the total fluorine (F) loss over 820 h accounts for 2-3% of total amount of F in the membrane.

Also observed in Fig. 13 is a change in mechanical stress-strain behavior that occurs for a change in ambient pressure between p = 4 kb and p = 5 kb. The authors speak of this as a pressure-induced transition. Another interpretation of... 

In our previous paper (2), we proposed a possible mechanism to interpret the stress-strain behavior of gradient polymers. We perceived the gradient polymer as consisting of infinite number of layers of varying compositions. Upon deformation, the macroscopic strain is the same for the entire sample. Because of the fact that the moduli of the various... 

A plastic material is defined as one that does not undergo a permanent deformation until a certain yield stress has been exceeded. A perfectly plastic body showing no elasticity would have the stress-strain behavior depicted in Figure 8-15. Under influence of a small stress, no deformation occurs when the stress is increased, the material will suddenly start to flow at applied stress a(t (the yield stress). The material will then continue to flow at the same stress until this is removed the material retains its total deformation. In reality, few bodies are perfectly plastic rather, they are plasto-elastic or plasto-viscoelastic. The mechanical model used to represent a plastic body, also called a St. Venant body, is a friction element. The... 

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