Effects of Loading Rate

However, at — 30 °C, unstable fracture occurs in some samples for loading speeds above 6000 mm/min. For both temperatures, as strain rate augments, G increases slightly before decreasing to a minimum value and then rises sharply in the region of impact loading. 

It can be seen from this equation that the same intercept of 7 versus Ta plot suggests a constant value of (d Wld V) since r is a constant, as discussed above. The results are in agreement with those reported by others [26,27] and suggests that the critical strain energy density controls the fracture behavior of the 

The observed peak in fracture energy is similar to that reported in the literature for many polymers [28-32]. In these reported cases, the observed peak has often been suggested to be due to the molecular relaxation process. The brittle behavior for temperatures below the peak implies that the molecular motions are limited. Above the transition temperature, the ductile behavior offracture indicates that movements of certain segments or regions of macromolecules 

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Fig. 26 Effect of loading rate on the diametrical breaking strength of tablets compressed at different levels. (From Ref. 123.)...

L. S. Costin and J. Duffy, The Effect of Loading Rate and Temperature on the Initiation of Fracture in a Mild, Rate Sensitive Steel, J. Engr. Material Technol., 101, 258-264 (1979). 

K.-H. Yang, A. S. Kobayashi, and A. F. Emery, Effects of Loading Rates and Temperature on Dynamic Fracture of Ceramics and Ceramic Matrix Composites, in Ceramic Materials and Components for Engines, eds. V. J. Tennery and M. K. Ferber, American Ceramic Society, Columbus, OH, 1989, pp. 766-775. 

FIGURE 7.9 Effect of loading rate (dKIdt) on critical stress intensity factor for crack extension (K/ff) in a low-alloy steel. Data are for high-strength steel tested in low-pressure hydrogen gas. 

The effects of loading rate on fracture energy at 23 and —30 °C are shown in Figure 27.10. The crack propagation is stable for all loading rates at 23 CC. 

Figure 27.10 Effect of loading rate on fracture energy of HIPS at (a) 23 and (b) -30 °C. Reprinted from Vu-Khanh, Theor. Appl. Fract. Mech., 29(2), 75(1998) with permission of Elsevier Science...

Meimon and Flicher (1980) correlated the post-cyclic undrained shear strength of two laboratory-prepared clays (with OCR = 1 and OCR = 4), with maximum permanent axial strain. They found that if the maximum permanent strain did not exceed 5%, the reduction in undrained shear strength was lower than 8%. With increasing strain level, the reduction could reach up to 40%. Experimental results also showed that the reduction did not necessarily depend upon OCR. The effect of loading rate has also been shown to influence... 

Kan Kanchanomai, C., Rattananon, S., Soni, M. Effects of loading rate on firacture behavior and mechanism of thermoset epoxy resin. Polym. Testing 24 (2005) 886-892. 

Bao, S. P. and Tjong, S. C. 2008. Mechanical behaviors of polypropylene/carbon nanotube nanocomposites The effects of loading rate and temperature. Materials Science and Engineering A 485 508-516. 

The effect of loading rate on the room temperature flexural strength of two additional SI N ceramics (PY6 and EC-152) was also Investigated as a result of the data obtained for NT-154. 

Fig. 3.1-167 Effect of loading rate on cyclic plastic strain of recrystallized Ta during a tension-compression cycle (R=—l). Stress amplitude = 120 MPa test temperature = 25 C duration of a cycle at 0.042MPa/s = 190min, at 4.2MPa/s = 1.9 min maximum plastic strain rate at all loading rates = approx. 3xl0 s [1.140]...

Elastic and strength properties at temperature in the range 40-150°C Effect of loading rate on tensile and compressive properties in the range 0.00167-16.7 s ... 

Fig. 27. The effect of loading rate on the mode of fracture of a high molecular weight PR...

Effects of loading rate and dynamic force spectrum (DFS)... 

Figure 11.2 Stress-strain curves of plain concrete subjected to static and impact loading. Reprinted from Cement and Concrete Research, Vol 34, Sukontasukkul, R Nimityongskul, R Mindess, S., Effect of loading rate on damage of concrete , pp. 8., Copyright (2004), with permission from Elsevier.

Tandon, S., Faber, K. T. (1999) Effects of loading rate on the fracture of cementitious materials, Cement and Concrete Research, 29 397-406. 

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