Jenike direct shear test

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. 

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. 

A useful approximation of B for a conical hopper is B = 22f/a, where a is the bulk density of the stored product. The apparatus for determining the properties of solids has been developed and is offered for sale by the consulting firm of Jenike and Johansen, Winchester, Massachusetts, which also performs these tests on a contract basis. The flow-factor FF tester, a constant-rate-of-strain, direct-shear-type machine, gives the locus of points for the FF cui ve as well as ( ), the... 

Direct and indirect shear stress equipment is usually limited to research projects because of the expense, the skill and time evolved to determine the yield loci and failure functions of particulate materials from bi- and ffi-axial shear testers. The designation of which type of shear tester has been used may be defined by the location of the shear failure zone. With direct shear testers - Jenike type - the major principal stress rotates during shear (Figure 1.35), whilst with indirect shear testers - tri- and bi-axial - the directions of the principal stresses are fixed and orientated in either three or two dimensions, respectively, and remain constant during the test. 

Fig. 17 shows the Jenike shear cell in a schematic diagram a circular (internal diameter 95 mm), open-ended shear box is split horizontally, the base is immobile and the ring can slide freely in the horizontal direction. The normal stress, which is applied via the lid, is first used to consolidate the specimen and then to load it during test. 

The failure function can be measured directly in a number of ways. Some are rather complex and still under development, like the new plane strain biaxial tester with flexible boundaries30, but the simplest method so far is the uniaxial compression test. Only the version developed by Williams et al,24 gives results close to those obtained indirectly with the Jenike shear cell, the other versions yield relative measurements only. 

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