Diagrams load-time

The overall dynamic load on structures has been evaluated by tests and analytical evaluations. The corresponding load-time diagram is shown in Figure 17-1 for a Phantom F-4. 

Figure 17-2. Example of another load-time diagram.

The design is based on the load-time diagrams Cl and C2 (see Fig. 1-8) applied to a circular area of 7 m, with the aim of ensuring the protection of equipment needed to shut down the reactor and to prevent core melt without redundancy ... 

In addition, the load-time diagram C2 is used for the design to the ultimate limit state of ... 

FIG. 4—Deformation time diagram loaded 20% the compressive strength at the given humidity... 

Isochronic stress/strain diagrams are more informative than creep strength diagrams. They are obtained by holding samples under a constant load for various lengths of time. Finally, a stress/strain diagram is obtained for each load time. 

Figure 1.73 illustrates the instrumented CIT system in a block diagram and the impact-response curve method, as applied to the above tests. In addition to the aforementioned partially stabilized zirconia (PSZ ZrOi-S mol%Y203), samples of S3N4 were also investigated by Kobayashi et al. [32], Typical hammer load-times and strain-gage signal-time curves of PSZ and Si3N4 are found in Fig. 1.74. The impact-response curves of PSZ and S3N4, at several impact velocities are shown in Fig. 1.75. The impact curves of these specimens are impact-velocity-dependent. This technique enables the determination of the dynamic fracture toughness of these ceramics by means of the impact-response curve method. Impact-response curves quantitatively relate the response of the specimen to the impact, which depends solely on the elastic reaction between the specimen and the actual impact.

Having determined value t as duration of linear part of diagram load -time P -1) in impact tests and accepting is equal to clusters relative fraction in quasistatic tensile tests [92], the values (p, (r) can be estimated. In Fig. 4.22, the dependences on strain rate for HOPE and polypropylene (PP) are shovm, which demonstrate increase at strain rate growth, that is, tests temporal scale decrease. 

Time-dependent failure behavior can be visualized as interposed 3-dimensional failure diagrams (Figure 1.54), where the outer body exhibits higher creep resistance due to its shorter loading time. Actual measurement results are not available. 

The authors of papers [6, 7] found out, that the introduction of particulate nanofiller (calciiun carbonate (CaCOj)) into high density polyethylene (HDPE) results in nanocomposites HDPE/CaCOj impact toughness in comparison with the initial polymer by about 20%. The authors [6, 7] performed this effect detailed fractographic analysis and explained the observed increase by nanocomposites HDPE/CaCOj plastic deformation mechanism change in comparison with the initial HDPE. Without going into details of the indicated analysis, one should note some reasons for doubts in its correctness. In Figure 9.1 the schematic diagrams load-time... 

FIGURE 9.1 The schematic diagrams load-time (P-t) in instrumented impact tests. Failure by instable (a) and stable (b) crack. 

The sulfur-containing epoxy polymers, cured by both aromatic diamines (DADPS and DADPM) and Iso-methyltetrahydrophthalic anhydride (IMTHPhA) (see Section 5.4), were studied. The fact that two of the studied epoxy polymers showed plastic fracture in impact loading conditions (SCE-DADPS - 1.2 and SCE-DADPS - 1.3, where the figure in conditional sign indicates the value of KJ. The diagram load-time (P -1),... 

Figure 6.18 The diagram of load-time (P - t) for plastic fracture of epoxy polymer SCE-DADPS - 1.2, plotted by averaging the results of five experimental diagrams...

Figure 8.12 The diagrams of load-time P-t) for samples with a sharp notch by length 0.5 mm of initial HDPE (1) and HDPE/EP nanocomposite with epoxy polymer content 2.5 mass percentage (2). Testing temperature 293 K, strain rate...

A third alternative way of presenting the time-dependent stress—strain relationship due to creep under static load conditions is to plot the creep modulus Edt) on a logarithmic timescale. Provided that the materials creep is linear viscoelastic, data at different stress levels should cause similar time-dependent values of creep modulus. The schematic approach for converting creep data into a creep modulus versus time diagram is illustrated in Fig. 34.9. 

Creep strength-time diagram based on a set of creep experiments at different levels of static load... 

Fig. 4X When x-cut quartz is subjected to impact loading whose duration is less than wave transit time, an anomalous current pulse can be observed after the stress release. The diagram shows locations at which experiments were conducted and delineates the region of normal and anomalous response (after Graham and Ingram ([72G03]).

Fig. 1.19 Potential-pH diagram for copper in solutions containing and (NH4>2S04 (after Mattson ) with superimposed times to fracture Tf of direct-loaded a-brass wires held at various potentials in the solution of pH 7-2 the specimen without external polarisation had Ff = 3y h (after Hoar and Booker S)...

As an example, for room-temperature applications most metals can be considered to be truly elastic. When stresses beyond the yield point are permitted in the design, permanent deformation is considered to be a function only of applied load and can be determined directly from the stress-strain diagram. The behavior of most plastics is much more dependent on the time of application of the load, the past history of loading, the current and past temperature cycles, and the environmental conditions. Ignorance of these conditions has resulted in the appearance on the market of plastic products that were improperly designed. Fortunately, product performance has been greatly improved as the amount of technical information on the mechanical properties of plastics has increased in the past half century. More importantly, designers have become more familiar with the behavior of plastics rather than... 

Fig. 20. Schematic diagram showing the estimation of the time-average rate of S02 oxidation under periodic flow interruption or reduction employing steady-state oxidation rate vs liquid loading data (Figure from Haure etal., 1989, with permission, 1989, American Institute of Chemical Engineers.)...

The situation where we may find the load function dead time is larger than that in the feedforward path of GmG vGp is not obvious from our simplified block diagram. Such a... 

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