Standard shear testing technique

ASTM D 6113-(yi. Standard Shear Test Technique. American Society for Testing Materials, International, West Conshohocken, PA. www.astm.org. 

Standard Shear Testing Technique for particulate solids using the Jenike shear cell (1989) Institution of Chemical Engineers, George E Davis Building, Railway Terrace, Rugby, UK, pp. 167-171. 

Time dependent behaviour is well known for moist bulk solids like clay. For dry bulk solids a time dependent behaviour has always been neglected in practical applications. This is because an influence of any time dependent effect on the results obtained from the Standard Shear Testing Technique [1] has not been found yet. The typical devices used for shear testing are the Jenike Tester and the Ring Shear Tester. These devices deliver a shear stress in dependence of the applied normal stress which is not effected by the shear rate... 

Shear strength is measured via a simple single overlap shear specimen of standard dimensions (Fig. 9). In contrast to its simple appearance, the forces in a thin-adherend shear specimen can be quite complex due to the inherent offset loading of the specimen and subsequent bending in the substrates. The single overlap shear test is anything but a pure shear test, but the configuration is easy to manufacture, simple to test and is firmly entrenched in the industry as a primary examination technique for materials qualifications, inspection and process control. 

The Jenike shear cell has been considered for long time the testing cell for establishing standard procedures in industrial applications and research. It has been recognized as one of the standards for testing bulk solids in the United States and in Europe, being especially focused on cohesive powders. The complexity of this method is such that errors due to poor technique can easily arise. A reference material has therefore been produced with which laboratories can verify both their equipment and experimental technique. The reference material consists of 3 kg of limestone powder packed in a polyethylene jar. It is accompanied by a certificate giving shear stress as a function of normal applied stress for four different powder compaction stresses. 

The technique of shear testing has traditionally been used to determine the shear behavior of consolidated powders. As discussed previously the Jenike shear cell testing is generally accepted as an established method for measuring powder flowability and standards based on it have been issued, both in Europe and the United States. Some disadvantages of the Jenike shear cell have also been mentioned. The process is extremely time consuming and tedious and correct consolidation of sample is difficult to achieve. It can be hardly used for all types of bulk solids due to its limited shear... 

Lap shear test conditions are not really convenient in electronics involving small dice and two substrates with different thermal expansion coefficients (CTE). The stresses generated during the cure cycle by this CTE mismatch account for possible crack formation and delamination, which in turn may degrade the adhesive strength. The die shear strength method consists in the measurement of the force required to shear the die from the chip carrier. Although any die size can be used, a standard technique is to bond 1.27 X 1.27 mm non-functional silicon dice to silver-plated lead frames. 

As stated earlier, adhesion is a major concern in electronic applications involving thin polyimide films either coated on hard substrates or laminated with metal ribbons. In these cases, neither lap-shear nor die-shear techniques allow the determination of the adhesion strength this can be done by using either the 90° peel test or the island blister test whose principles are sketched in Figs 12.26 and 12.27. The 90° peel test provides reliable data for the measurement of practical adhesion, especially useful for comparing the effect of surface treatments on the interfacial adhesion. The standard peel test procedure has been modified to determine the adhesive strength of thin polyimide films coated onto 10-cm silicon wafers. The equipment illustrated in Fig. 12.26 maintains a 90° peel effort during the test conducted at room temperature with a constant rate of crosshead displacement of 2 mm min . ... 

There is some evidence to suggest that, depending upon the phase volume ratios employed, the emulsification technique used can be of greater importance in determining the final emulsion type than the H LB values of the surfactants themselves [434], As an empirical scale the HLB values are determined by a standardized test procedure. However, the HLB classification for oil phases in terms of the required HLB values is apparently greatly dependent on the emulsification conditions and process for some phase-volume ratios. When an emulsification procedure involves high shear, or when a 50/50 phase volume ratio is used, interpretations based on the classical HLB system appear to remain valid. However, at other phase-volume ratios and especially under low shear emulsification conditions, inverted, concentrated emulsions may form at unexpected HLB values [434]. This is illustrated in Figures 7.4 and 7.5. 

Resin synthesis, adhesive formulation, and evaluation techniques are described by Clark et al. (3,4) Plywood shear specimens were prepared according to U.S. Product Standard PS 1-83 for exterior plywood (5). Glulam shear specimens were tested according to the American Institute of Timber Construction (AITC) standards AITC-T107 and AITC-T110 for dry shear and vacuum-pressure soak (3). Glulam test specimens were also subjected to a 2-hour boil treatment (not an AITC test) prior to shear (7,8). 13C-NMR spectra were recorded at 100.6 MHz on a Bruker AM-400 NMR spectrometer. Gel permeation chromatography... 

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