Uniaxial loading

As it was determined by the test, the stretch diagram at the uniaxial load carrying ability of the carbon plastic UKN-5000 is almost linear until the destruction point. The samples are breaking brittle, and the relative deformation is small (E < 2%). 

Figure 2-26 Uniaxial Loading at 45° to the 1-Direction Then, by use of the modulus transformation relations in Equation (2.97)...

For each of the failure criteria, we will generate biaxial stresses by off-axis loading of a unidirectionally reinforced lamina. That is, the uniaxial off-axis stress at 0 to the fibers is transformed into biaxial stresses in the principal material coordinates as shown in Figure 2-35. From the stress-transformation equations in Figure 2-35, a uniaxial loading obviously cannot produce a state of mixed tension and compression in principal material coordinates. Thus, some other loading state must be applied to test any failure criterion against a condition of mixed tension and compression. 

Figure 2-35 Biaxial Stresses from Off-Axis Uniaxial Loading...

In applications of the maximum stress criterion, the stresses in the body under consideration must be transformed to stresses in the principal material coordinates. For example, Tsai [2-21] considered a unidirec-tionally reinforced composite lamina subjected to uniaxial load at angle 6 to the fibers as shown in Figure 2-35. The biaxial stresses in the principal material coordinates are obtained by transformation of the uniaxial stress, a, as... 

For a unidirectionally reinforced composite material subject to uniaxial load at angle 0 to the fibers (the example problem in Section 2.9.1 on the maximum stress criterion), the allowable stresses can be found from the allowable strains X, Y , etc., in the following manner. 

As with the maximum stress failure criterion, the maximum strain failure criterion can be plotted against available experimental results for uniaxial loading of an off-axis composite material. The discrepancies between experimental results and the prediction in Figure 2-38 are similar to, but even more pronounced than, those for the maximum stress failure criterion in Figure 2-37. Thus, the appropriate failure criterion for this E-glass-epoxy composite material still has not been found. 

Most components of the strength tensors are defined in terms of the engineering strengths already discussed. For example, consider a uniaxial load on a specimen in the 1-direction. Under tensile load, the engineering strength is Xj, whereas under compressive load, it is (for example, Xg = -400 ksi (-2760 MPa) for boron-epoxy). Thus, under tensile load. 

Angle-ply laminates have more complicated stiffness matrices than cross-ply laminates because nontrivial coordinate transformations are involved. However, the behavior of simple angle-ply laminates (only one angle, i.e., a) will be shown to be simpler than that of cross-ply laminates because no knee results in the load-deformation diagram under uniaxial loading. Other than the preceding two differences, analysis of angle-ply laminates is conceptually the same as that of cross-ply laminates. 

Dead-weight loading (with or without the assistance of levers to reduce the load requirements) of tensile specimens has the advantage of avoiding some of the difficulties already discussed, not the least in allowing accurate determination of the stress if the specimen is uniaxially loaded. The relatively massive machinery usually required for such tests upon specimens of appreciable cross section is sometimes circumvented by the use of a... 

Method for the preparation and use of uniaxially loaded tension specimens Method for the preparation and use of C-ring specimens... 

Fiber Symmetry Equator and Meridian. Figure 4.1 sketches a scattering experiment of a polymer sample under uniaxial load. Let us assume that the material... 

The numerical simulations of the stress distributions are carried out on porous materials submitted to uniaxial loading. In order to check the validity of the numerical simulations, macroporous epoxies are prepared via the CIPS technique. Cyclohexane is selected as the solvent, thus resulting in the formation of a closed porosity, and the statistical distribution of the voids coincides with the random distribution of the model system. The structural characteristics of these materials prepared by curing at T=80 °C are summarized in Table 4. 

At fixed (ambient) pressure, a Clausius-Clapeyron equation relates the change in transformation temperature with applied uniaxial load ... 

In Sections 4.4 and 4.5, we dealt briefly with particulate flow instabilities in hoppers and the nonhomogeneous stress distributions created under uniaxial loading of a particulate assembly. In this section, we will expand on the discrete nature of such assemblies, and refer the reader to the computational and experimental tools that have been developed, and are rapidly advancing, to study such phenomena. 

Najafbadi and Yip (18) have investigated the stress-strain relationship in iron under uniaxial loading by means of a MC simulation in the isostress isothermal ensemble. At finite temperatures, a reversible b.c.c. to f.c.c. transformation occurs with hysteresis. They found that the transformation takes place by the Bain mechanism and is accompanied by sudden and uniform changes in local strain. The critical values of stress required to transform from the b.c.c. to the f.c.c. structure or vice versa are lower than those obtained from static calculations. Parrinello and Rahman (14) investigated the behavior of a single crystal of Ni under uniform uniaxial compressive and tensile loads and found that for uniaxial tensile loads less than a critical value, the f.c.c. Ni crystal expanded along the axis of stress reversibly. 

Consider a continuous fiber-reinforced ceramic as a multiphase system where the individual phases are parallel to one another and to the uniaxial loading direction. The fibers (or fiber bundles), matrix, and interface zone are treated as individual phases. In general, each phase undergoes elastic-plastic (creep) deformation. In the present analysis, the creep rate of each phase, e is assumed to obey a general creep law of the following form... 

Most HIPS fail in the uniaxial loading of a cantilever impact (Izod) test only if the test specimens have been notched beforehand. In the notched impact test, the stress direction in injection molded specimens is the same as the preferred orientation direction. This increases the measured impact toughness and the flexural impact test and, therefore, serves primarily for comparing the toughness of different products. 

Stratum corneum breaking strength decreases fourfold over the 0-100% RH range reaching a minimum at approximately 90% RH which is not lowered further by immersion in water. Of fundamental importance is the morphological location within the stratum corneum where failure occurs under a uniaxial load. Scanning electron microscopy (SEM) and conventional analysis of fractured samples indicate that the samples predominately fracture within the intercellular junctions rather than intracellularly (9). 

In our case, these evaluations clearly point out an increase in volume (most presumably related to a cavitation process) during tensile deformation for all modifred products even under uniaxial loading conditions. This increase in volume can reach 15 %. In the same evaluations, the unmodified PET, either amorphous or semi-crystalline, shows little or no volume change. 

The elasto plastic behavior of a compositionally graded metal-ceramic structure is investigated. The deformation under uniaxial loading is predicted using both an incremental Mori-Tanaka method and periodic as well as random microstructure extended unit cell approaches. The latter are able to give an accurate description of the local microfields within the phases. Furthermore, the random microstructure unit cell model can represent the interwoven structure at volume fractions close to 50%. Due to the high computational costs, such unit cell analyses are restricted to two-dimensional considerations. 

The investigated structure (cf. fig. 1) consists of a pure nickel top layer (1.2mm thick), an FGM zone with a linear variation of the volume fraction (2.2mm thick), and a pure alumina bottom layer (0.45mm thick). Material data of the constituents are given in table 1, where Eh denotes the strain hardening modulus. The boundary conditions force all cross sections perpendicular to the monolithic/FGM interfaces to remain plane, i.e. the lefthand and the righthand side (as well as the viewing plane for three-dimensional considerations). The uniaxial load (which causes extension and bending for the present... 

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