Influence of loading rate

The influence of loading rate during shock loading on the defect generation and storage proeesses has been examined in OFE eopper shoek loaded using three different loading rates [51]. These include ... 

G.T. Gray III and C.E. Morris, Influence of Loading Rate of the Mechanical Response and Substructure Evolution of Shock-Loaded Copper, in DYMAT 91, Journal De Physique IV, Colloque C3, Suppl. an Journal de Physique III, Vol. 1 (1991), C3-191. 

Interest in the use of syntactic foam as a shock attenuator led to studies of its static and dynamic mechanical properties. Particularly important is the influence of loading rate on stiffness and crushing strength, since oversensitivity of either of these parameters can complicate the prediction of the effectiveness of a foam system as an energy absorber. 

Influence of loading rate on fiber and matrix stress... 

Fig. 6.3 Influence of loading rate on the monotonic stress-strain behavior of unidirectional Nicalon SiCf/CAS-II composites tested in air at 20°C. As the loading rate decreases, the proportional limit, ultimate strength and failure strain decrease. After S0rensen and Holmes.39...

The first two terms on the right-hand side of equation [12.6] are viscoelastic terms proposed by Schapery, where e represents uniaxial kinematic (or total) strain at time t, o is the Cauchy stress at time t, is the instantaneous compliance and AD(r[i ) is a transient creep compliance function. The factor g defines stress and temperature effects on the instantaneous elastic compliance and is a measure of state dependent reduction (or increase) in stiffness. Transient compliance factor gi has a similar meaning, operating on the creep compliance component. The factor gj accounts for the influence of loading rate on creep. The function i ) represents a reduced timescale parameter defined by ... 

In more recent work embrittlement in water vapour-saturated air and in various aqueous solutions has been systematically examined together with the influence of strain rate, alloy composition and loading mode, all in conjunction with various metallographic techniques. The general conclusion is that stress-corrosion crack propagation in aluminium alloys under open circuit conditions is mainly caused by hydrogen embrittlement, but that there is a component of the fracture process that is caused by dissolution. The relative importance of these two processes may well vary between alloys of different composition or even between specimens of an alloy that have been heat treated differently. 

Regions below the loading point as well as the loading region itself are apparent from liquid holdup and interfacial area data as shown in Figure 12.52. At low rates, there is little influence of vapor rate on holdup and interfacial area. This behavior is typical of random as well as structured packings. In the latter, the effects of the rates on interfacial area seem to be less pronounced than for random packings. The appearance of the flood point in the holdup and area plots will undoubtedly match the flood point in the pressure drop. 

The vi,scoelastic nature of the polymeric materials has necessitated studies that e.xam-ine the influence of the rate of loading and the test temperature on the fracture properties. The influence of impact speed on Ki and 6 it has been evaluated for PC [5], PMMA [5.73], HOPE [46], PS [80], MDPE [81], uPVC [82], nylon 6,6 [67,5], and polyacctal [5.68,74], Some of these studies [82, 60] also include the influence of temperature on the properties. 

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... 

In the analyses of cyclic pile response it is necessary to consider the influence of load magnitude, rate, and number of cycles on the following factors ... 

Figure 16 shows the influence of the rate of load application in the tensile test in qualitative terms. Section 2.5 describes the time-dependence of the material properties in detail. 

Glinicki, M. A. (1991) Influence of the rate of loading on the strength and deformation of cement matrix composites (in Polish), PhD Thesis, IFTR, Warsaw Rep.l. 

---