Vertical load tests

The shear cell is filled in a standard manner to produce a powder bed with a constant bulk density. A vertical (normal) force is applied to the powder bed and a horizontal force applied to the moveable ring. As the powder bed moves due to the horizontal shear stress, it will change volume, either expanding or contracting depending on the magnitude of the vertical force. A series of tests are performed to determine the vertical load under which the bed remains at constant volume when sheared, referred to as the critical state. Once the critical state has been determined, a series of identical specimens are prepared, and each is sheared under a different vertical load, with all loads being less than the critical state. 

There are numerous techniques known for adhesion and delamination testing, some of the most common being a tape test, stud-pull test, scratch test, and an indentation test [1]. In the tape test, a tape is pulled off the surface containing a scratch, which provides the failure initiation. In the stud pull test, a stud held with thermosetting epoxy is pulled off the film surface. The indentation test, wherein a ball is pressed into the surface, is used for hard coatings, and the failure pattern indicates acceptable behavior. In the scratch test, where an indenter moves in both vertical (loading) and horizontal (sliding) directions, an acoustic emission sensor allows for detection of the initiation of fiacture, while the scratch pattern indicates the type of failure. 

The influence of temperature on the compressibility of unsaturated clay has been studied by compression tests in oedometric conditions. The initial dry density of the samples has been 1.70 g/cm, and the clay was compacted uniaxially with its hygroscopic water content inside the oedometer ring (diameter of 5.0 cm, length of the specimen of 1.2 cm). A vertical pressure between 22 and 26 MPa was applied to manufacture the specimens. Three different samples were heated up to 25, 60 and 80 °C under a low vertical load (0.4 MPa). Afterwards, the samples were progressively loaded by steps up to 20 MPa. The tests were performed in an... 

In this type of tests the combined effect of the temperature and the hydration on the behaviour of the clay was investigated. The tests were performed at 25 and 80 C in the oedometer shown in Figure 2, and the procedure to manufacture the samples was the same described in section 3.1. After the initial heating under a low vertical stress, the samples were saturated with distilled water under a vertical load of 1 MPa. Afterwards, the vertical load was progressively increased up to 20 MPa. 

Three tests on bentonite compacted at an initial dry density of 1.7 g/cm with its hygroscopic water content have been performed at different temperatures (20, 40 and 60 °C), following the suction and stress paths indicated in Figure 4. In the first step, under a vertical load of 0.1 MPa, the suction of the sample was equalised to 14 MPa (due to mechanical limitations of the cell, this is the maximum suction that can be controlled). Afterwards, keeping this suction constant, the vertical load was increased up to 5 MPa. Under this vertical load, suction was decreased by steps until... 

The permeation experiments were carried out on 2 cm thick clay specimens placed into an aluminium cylinder of 5.38 cm diameter. The testing equipment allows the generation of a constant flow rate using a piston moving at a constant velocity. The chamber of the piston is connected to the fluid chamber in the permeameter cell located above the clay specimen, which is toped by a porous stone. A pressure transducer is connected to the hydraulic circuit. The fluid outlet in the lower aluminium plate is kept at atmospheric pressure. An external vertical load is applied to the specimen by means of a spring-loaded cap prior to permeation. Vertical settlements are monitored using a dial gauge and a settlement rod mounted on top of the specimen. 

To help minimize the variation in vertical load and movement during sampling or testing, a sea clamp is used on the seabed. The seabed clamp is just a large weight that is clamped onto the drill string to resist the vertical cyclic motion. 

Tension tests according to DIN EN ISO 527 were carried out on the laminates with six tests per series to determine their tensile strength, the tensile e-modulus and the breaking point. Measurement of stretch characteristics was made using a video extensometer under standard weather conditions (23 2°C, 50 5% relative density) according to DIN 50014-23/50-2, i.e. three measurements, 0.01 mm exactness. For the determination of the force-tension range, the e-modulus was between e i = 0.05% and e"2 = 0.25%. Wind and snow loads were calculated as vertical loads. Other temporary loads have also been calculated as vertical pressure loads. An example for a rib type 350 is shown in Fig. 15.22. 

In the finite element analysis model, normal constraints were applied at the bottom and the vertical load was applied at the top as shown in the Figure 1. Similar to the load test in laboratory, a e curve is available by numerical load test, e is... 

A small amount of Melapur 200 (melamine polyphosphate) with a metal hydrate leads to a strong reduction in the rate of heat release. The combination allows a lowering of the loading to 50% instead of 65% and still retains the same peak rate of heat release as with 65% magnesium hydroxide in EVA. The effect of Firebrake ZB has been shown to further reduce the overall level of heat release and create a hard, cellular protective structure. In vertical bum tests like UL94, however, this stmcture is not created and leads to a loss of classification. Current work is endeavouring to improve vertical burning behaviour of these formulations. 

The test uses a vertically loaded stylus of a hard material such as diamond or tungsten carbide with a tip radius of the order of tens of micrometres. A micro-hardness tester may be used to make the test. The stylus is drawn across the film a number of times, the vertical load being increased for each traverse. The critical load at which the film is just removed from the substrate is usually taken as a measure of the adhesion. - A European Standard has been estabhshed by the European Standards Committee CEN TC184 WGS. ... 

In an in situ shear test, a block of rock is sheared from a rock surface while a horizontal jack exerts a vertical load. It is advantageous to make the tests inside galleries, where... 

The availability of reliable isolators models will allow the number of quite costly experimental tests on complete bearings to be considerably limited, not only as regards the analysis of the effects of some important parameters (e.g. temperature, ageing, vertical load on horizontal stiffness, etc.), but also for complicated experiments such as for instance, failure tests and analysis of the effects of defects. 

Second method is shear test (Vane Cone Shear Test, VCST), in-situ cohesion and friction angle are independently measured in half an hour. Figure 8 shows relationship between VCST and tri-axial compression test or simple shear test in several soil samples. Initial torque, which is the torque when vertical load is zero, correlates to cohesion by tri-axial test. Furthermore, trend angle of approximation line by VCST correlates to friction angle. 

The preliminary reduction (reconsolidation) of the samples before recovery of its natural density, was made by recovery phase composition method. Vertical load was put with earlier reached pressure in a chamber and blocked drainage under kinematic mode of loading, with a speed of 0.5% in a minute. Defended deformation characteristics were modulus of deformation and Poisson s ratio. The durability of samples was estimated by the meaning of the resistance of undrainaged shear. For their definition the soil samples were tested by putting vertical load under the set comprehensive pressure... 

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