Quasi-static tests

Gray and Follansbee [44] quasi-statically tested OFE copper samples that had been shock loaded to 10 GPa and pulse durations of 0.1 fis, 1 /rs, and 2 fus. The quasi-static stress-strain curves are shown in Fig. 7.10 with the response of annealed starting copper included for comparison. The yield strength of shock-loaded copper is observed to increase with pulse duration, as the work-hardening rate is seen to systematically decrease. 

Far from a wellbore, the velocity of reservoir fluids is about one linear foot per day. Near a wellbore, the velocity can increase one-hundred fold. A static or quasi-static test such as the sessile drop (contact angle) test may not represent the dynamic behavior of the fluids in the field. The dynamic Wilhelmy device gives results which are comparable in interface velocity to the field displacement rate. The interface in the Wilhelmy test described here moved at a steady rate of 0.127 mm/sec or 36 ft/day. The wetting cycle for a hybrid-wetting crude oil system was not affected by moving at a rate less than 1 ft/day. 

The available data for unidirectionally reinforced laminates are typically interpreted such that mode I values seem to constitute a lower bound compared to the other modes, specifically mode II, at least for quasi-static tests. For cyclic fatigue delamination tests, it has been shown by Martin and Murri [59] that cyclic delamination fatigue for CFRP... 

It should be noted that the composites damage and failure models discussed here are based on an assumption of rate-independent behaviour, and materials properties used for validation studies are based on quasi-static tests. This is currently standard practice in impact simulations of composite structures, which is an important assumption in the work. Reasons for this are the lack of international dynamic test standards for measuring rate-dependent composites properties, so established test procedures are missing. Dynamic failure models for composites are not well understood nor implemented in current commercial FE codes. In justification it should be pointed out that carbon fibres are highly elastic, thus fibre-dominated properties show no... 

Quasi-static and dynamic tests were conducted at the DLR Institute of Stmctores and Design, Stuttgart. The quasi-static test was conducted in a Zwick 1494 servo-hydraulic uniaxial loading frame (max. loads 500 kN, max. crosshead displacement 850 mm) with the stmcture test setup as shown in Figure 10.14(a). Vertical compression loads were applied by the test machine crosshead via a load cell to the test stmcture through the I-beam and measured at the load cell and on the load platform. The test was performed initially at a crosshead velocity of 5 mm/min for the first 20 mm of crosshead displacement, then increased and maintained at 20 mm/min until final collapse at 62 mm crosshead displacement. From the measured load-deflection curve the absorbed energy at failure can be calculated, which was measured to be 6.3 kJ at 62 mm displacement. This energy represents... 

Short range Medium range Long range TEM, SEM, solid-state NMR, Raman, bound rubber Dynamic-mechanical tests Tensile, quasi-static tests, Raman Interface Break-up of nanofiller network Strength of nanofiller-rubber interaction... 

Despite having reached ultimate conditions, specimen no. 1 sustained with little further strength degradation another quasi-static test of six cycles of lateral forces with inverted triangular distribution over all four floors (Fig. 16.8). Old cracks re-opened despite been epoxy-grouted, but the major one at the base monopolized the deformations when the top drift reached 1.2 %, its width exceeded 7 mm at one edge and 4 mm at the opposite. Interface slippage reached 3 mm at the base, but was modest at all other interfaces. 

Relying on the analysis of the experimental data, a number of works [3,4 et al] prove that for the description of long-standing relaxation processes in polymers under quasi-static tests two constituents of viscoelastic strain are to be taken into consideration in (3) and (4) — a... 

With specimens prepared in different ways, the results of quasi-static testing using spherical indenters of different diameters and those of fracture observation after impact tests using 1 mmcf) spherical particle were compared. 

When an atmospheric spray specimen was subjected to a quasi-static test with an indenter of 1 mmcj), both the substrate and the bond coat were affected with marked plastic deformation, and in particular, the substrate underwent so drastically that the limit of elastic-plastic deformation was stepped over to present a porous zone with concentrated cracks. As the indenter size grew, the area of plastic deformation in the substrate and the bond coat was reduced, to present Hertz cone cracks in the cross-section. In addition to Hertz cone cracks, a number of cracks were seen in parallel to the substrate, which were thought to have occurred when the load was eliminated. With an indenter of 4 mmcj), the area of plastic deformation was reduced further, and lateral cracks were observed as the load was eliminated. Debonding between the bond coat and the substrate was observed only with the 4-mm indenter. Comparing to impact tests results(Fig. 7), qusi-static tests(Fig. 14) can reproduce similar fracture behavior. 

Varley RJ, van der Zwaag S (2008) Development of a quasi-static test method to investigate the origin of self-healing in ionmners under ballistic conditions. Polym Test 27 11-19... 

The dynamic cone penetration test, like the quasi-static cone penetration test, comes in a variety of forms. It is undertaken in a manner similar to the standard cone penetration test but executed continuously to gather a full profile of penetration resistance, rather than at discrete intervals in a borehole. It is a useful test but is not very widely used in the dredging industry, which prefers the quasi-static test because the registration of the sleeve friction is not possible for a DCPT test. 

On the other hand, rather few quasi-static tests on unreinforced masonry buildings have been carried out allowing this validation. Many unreinforced masonry building models have been tested in shaking tables, but, in general, the dynamic experimental behavior is difficult to compare with the pushover response. 

Relationship 9.35 implies that the pressure applied in microhardness tests under an indentor is higher than the yield stress in quasi-static tests because of the restriction... 

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