Direct shear test

Shear tests Direct shear Triaxial Unconfined compression Investigation of stability of foundations, slopes, retaining walls... 

In order to develop the proper dow pattern, knowledge of a material s dow properties is essential. Standard test equipment and procedures for evaluating sohds dow properties are available (6). Direct shear tests, mn to measure a material s friction and cohesive properties, allow determination of hopper wall angles for mass dow and the opening size required to prevent arching. Other devices available to evaluate sohds dowabiUty include biaxial and rotary shear testers. 

Engineering constants (sometimes known as technical constants) are generalized Young s moduli, Poisson s ratios, and shear moduli as well as some other behavioral constants that will be discussed in Section 2.6. These constants are measured in simple tests such as uniaxial tension or pure shear tests. Thus, these constants with their obvious physical interpretation have more direct meaning than the components... 

Direct shear tests are made in the laboratory to obtain data for determining the bearing capacity of soils and the stability of embankments. 

Triaxial compression tests are another means of determining shearing strength of a soil. A complex device is used to apply pressure along the sides of a cylindrical specimen and axially down the axis of the cylindrical specimen. In general, triaxial tests are superior to direct shear tests since there is better control over intake and discharge of water from the specimen. 

Direct shear test of soils under consolidated drained conditions Consolidated-undrained triaxial compression test on cohesive soils One-dimensional consolidation properties of soils One-dimensional consolidation properties of soils using controlled-strain loading... 

Waste settlement is another consideration. As waste settles in the landfill, a downward force will act on the primary FML. A low friction component between the FML and underlying material prevents that force from being transferred to the underlying material, putting tension on the primary FML. A 12-in. direct shear test is used to measure the friction angle between the FML and underlying material. 

The mechanical properties of a material describe how it responds to the application of either a force or a load. When this is compared to an area, it is called stress, another term for pressure. Three types of mechanical stress can affect a material tension (pulling), compression (pushing), and shear (tearing). Figure 15.27 shows the direction of the forces for these stresses. The mechanical tests consider each of these forces individually or in some combination. For example, tensile, compression, and shear tests only measure those individual forces. Flexural, impact, and hardness tests involve two or more forces simultaneously. 

It would be interesting to test this explanation by determining the shear alignment direction of the inverted triblock, PI-PS-PI, which has a styrene blocks in the middle. Presumably, if the above explanation for the prevalence of perpendicular alignment in PS-PI-PS is correct, then the inverted triblock PI-PS-PI should show parallel alignment at high frequencies. 

Introductory concepts A review of the differences between fluids and bulk solids. Cohesive strength tests A review of different shear test methods, the Jenike Direct Shear Test method, and the calculation of the design parameters to prevent arching and ratholing. 

The data generated experimentally from the Jenike direct shear test can be used to determine the following derived parameters ... 

Studies have also been conducted comparing the Jenike direct shear test method to other test methods used to measure a powder s flowability (3), including the Hosokawa Micron Powder Characteristics Tester (Hosokawa Micron, Osaka, Japan), Peschl shear tester, and Johanson Hang-up Indicizer (Johanson Innovations, San Luis Obispo, California, U.S.A.). This is not an exhaustive list of all the powder testers available. In general each tester has its own test method, which measures some property of the powder that changes as the flowability changes. As stated previously, however, the term flowability must be taken in context. 

For the determination of the thermal compatibility, the ASTM C 884-78 test method was followed. A layer of RPUMRPE mortar was applied to a slab of cured and air dried concrete. After the material cured for one week, the samples were subjected to five cycles of temperature change. In the first cycle, the specimens were placed in the environmental chamber at -6° 3°F (-21.1° 1,7°C) for 24 hours and then removed to room temperature at 73° 1,8°F (23 1°C) for 24 hours. Three beams with 1/2- to 2 inch (12- to 50-mm) overlays and four slab with 1/2-inch (12-mm) overlays were tested. No delaminations were found in the specimens. The direct shear tests were conducted to measure the effect of the thermal cycles. The results are shown in Table 8. 

Laboratory tests to determine shear strength are the direct shear test, the unconfined compression test, and the triaxial test. ASTM Standards give complete details of these tests. Triaxial tests yield the most reliable results. The manner in which these tests define the failure line as shown in Figure 2.4. 

Figure 5. Laboratory shear testing. Extruded polymer filament bonded between paper strips is sheared in directions of arrows.

The so-called shear cells are used for direct shear tests, where the powder specimen is consolidated in the vertical direction and then sheared in a horizontal plane. There are basically two types of shear cells in use today the Jenike shear cell (sometimes referred to more generally as the translational shear box) and the annular (or ring) shear cell (the rotational shear box). As the equipment needed is highly specialized (and hence outside the scope of this Guide) and as manufacturers instructions are usually adequate, the following contains only an outline description of both the hardware and the test procedures. 

Miyanami, K., and Terashita, K., Direct Shear Test of Powder Beds, Kona, Powder Science and Technology in Japan, 1, 1983, pp. 28-39. 

Scotch-tape test [13,16-20] Abrasion test [18,21] Bend and stretch test [15,22] Shearing stress test [22-24] Direct pull-off method [15,25-39] Moment or topple test [40-43] Electromagnetic tensile test [44] Laser spalation test [45] Ultracentrifuge test [13,22,46-50] Ultrasonic test [13,76] Peeling test (13, 51-54] Tangential-shear test [55,56] Scratch test [50,52, 57-73]... 

Figure 13 Weathering profile and some physical rock properties. UCS - unconfmed compressive strength, TS - tensile strength, E - Young s modulus, Wj - specific destruction work, Dj - dry density, P - porosity,

In general, the notched Charpy (ISO 179) [26] and Izod (ISO 180) [27] tests are not meaningful for composites, and ISO 179 recommends that only unnotched specimens should be tested. The difficulty with these tests is that in the notched condition the majority of specimens tested perpendicular to the plane of the test panel delaminate at the root of the notch. This reduces the specimen to a thinner version of the unnotched specimen, which as described above for the interlaminar shear test (see Section 5.4) is susceptible to compression-initiated failures under complex local loads. Specimens cut in the plane of the laminate or sheet will be less susceptible to delamination at the notch tip, and crack growth will be possible from the notch tip. However, other compression shear failure modes are still possible in some composites, and they will not be loaded in this direction in most applications. 

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