Shear testing, paper

In friability tests the material s susceptibility to attrition is evaluated. But it is not as simple as it may seem at first to select the suitable test procedure. In this context Pell (1990) gave a simple thought experiment to illustrate the difficulties If we took a batch of rubber stoppers and a batch of diamonds, and rubbed them on abrasive paper, we would conclude that the diamonds were more attrition resistant. If we instead struck the particles with a hammer we would conclude that the rubber were more attrition resistant. So, different test methods can rank materials differently with respect to their attritability. This effect was for example observed by Knight and Bridgwater (1985). They subjected spray-dried powders to a compression test, a shear test and a test in a spiral classifier. They found that each test gave a different ranking of the materials. Obviously, there is no... 

Among many shear-type tests the following are representative the mallet friction test, the sliding-block friction test, and the emery-paper friction test of the Explosives Research and Development Establishment, England, the U.S. Bureau of Mines pendulum friction test, and the Julius Peters friction test. Each of these can be used to test primary explosives, and some may be used also on secondary explosives. 

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

The 3D numerical model consisting of the colluvium and the bedrock was established in this paper. Stability analyses for the colluvium were performed using the commercial software Flac . The 3D model with 5042 points and 22365 zones is shown in Figure 6. The physical and mechanical parameters of the deposit and underlying bedrock obtained from physical properties measurement and direct shear test are sununarized in Table 1. 

The paper by C. E. Warburton concerning color printing on cloth binders examines cohesive and adhesive properties of pigment produced from the closely related copol3miers of ethyl or butyl acrylate with acrylonitrile. Modern tensile, peel and shear tests are used, and surface energies calculated. The unique system chosen allows a... 

Jcmes R Paschal (author s closure)— For the purposes of this paper, the only testing done directly on piping joints was the hydrostatic burst testing, shown as the Tail Pressure in Table 3. Conducting a controlled shear test on a joint is being considered as an alternative method within a separate project at ASTM. 

A shear wave transducer with the height H, and the width W on the wedge and at the angle a, transmitted shear waves, at the frequency f and perpendicular to the paper. The limited plane SH Waves were transmitted to the test surface. The height H of the transducer was considered by dividing it into N pieces. On the test surface in the areafW XHl), the transducer vibrated perpendicular to the paper where Hl=H/cos , the... 

Vacuum filters are usually simulated with a Buchner funnel test or filter leaf test (54). The measured parameters are cake weight, cake moisture, and filtration rate. Retention aids are usually evaluated using the Britt jar test, also called the Dynamic Drainage Jar, which simulates the shear conditions found on the paper machine and predicts performance (55). 

Frequently used single-point viscosity tests in the starch plant are orifice pipettes,56 orifice funnels,57 the Hot Scott viscometer, and various methods to determine alkaline fluidity.58 For absolute measurements of the rheological properties, rotating viscometers with coaxial cylinders are used.59 The paper industry uses mainly the Brookfield viscometer and the Hercules viscometer for determining shear-dependent viscosity, pseudoplasticity, and thixotropy. Oscillatory and capillary viscometers are used for more detailed viscosity characterization, such as yield value, elastic properties, and viscoelasticity.60... 

This paper presents results from a study of assemblies composed of glass fibre reinforced epoxy composites. First, tests performed to produce mixed mode fracture envelopes are presented. Then results from tests on lap shear and L-stiffener specimens are given. These enabled failure mechanisms to be examined in more detail using an image analysis technique to quantify local strain fields. Finally the application of a fracture-mechanics-based analysis to predict the failure loads of top-hat stiffeners with and without implanted bond-line defects is described. Correlation between test results and predictions is reasonable, but special attention is needed to account for size effects and micro-structural variations induced by the assembly process. 

The paper is presented in three parts. First, the tests employed to determine the mixed mode fracture envelope of a glass fibre reinforced epoxy composite adhesively bonded with either a brittle or a ductile adhesive are briefly described. These include mode I (DCB), and mixed mode (MMB) with various mixed mode (I/II) ratios. In the second part of the paper different structural joints will be discussed. These include single and double lap shear and L-specimens. In a recent European thematic network lap shear and double lap shear composite joints were tested, and predictions of failure load were made by different academic and industrial partners [9,10]. It was apparent that considerable differences existed between different analytical predictions and FE analyses, and correlation with tests proved complex. In particular, the progressive damage development in assemblies bonded with a ductile adhesive was not treated adequately. A more detailed study of damage mechanisms was therefore undertaken, using image analysis combined with microscopy to examine the crack tip strain fields and measure adherend displacements. This is described below and correlation is made between predicted displacements and failure loads, based on the mixed mode envelope determined previously, and measured values. 

Because high fluxes and the abdity to process streams containing suspended solids and fibers are often wanted in the pulp and paper industry, high-shear modules have been developed. Currently existing high-shear modules, excluding tubular modules, are modified plate and frame constructions. Both a cross-rotational module from Metso Paper and a vibration enhanced module (VSEP) from New Logic Inc. have been industrially used or tested in pulp and paper industry applications [48-51]. 

Rein, S.W., Randall, N.R, Marshall, H.T and Lewis, B.J. (1977) A mathematical technique for comparing shear stability in bench tests and service. SAE Paper 770633. 

Talbot, A.F., Wright, W.A. and Morris, H.l. (1973) A bench scale test for shear stability of multigrade engine oils. SAE Paper 730485. 

Dettman, L.P and Marsden, K. (1981) Shear stability testing of polymers in automotive lubricants. CEC International Symposium on the Performance Evaluation of Automotive Fuels and Lubricants. Paper EU4/4. 

Laukotka, E.M. (1989) Shear stability tests for polymer containing lubricating fluids. CEC 3rd International Symposium of Performance Evaluation for Automotive Fuels and Lubricants. Paper 3 LT. 

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