scholarly journals Non-coaxiality of sand under bi-directional shear loading

2018 ◽  
Vol 5 (5) ◽  
pp. 172076 ◽  
Author(s):  
Yao Li ◽  
Yunming Yang
Keyword(s):  
Shear Stress ◽  
Strain Rate ◽  
Simple Shear ◽  
Shear Test ◽  
Shear Loading ◽  
Shear Behaviour ◽  
Shear Stresses ◽  
Simple Shear Test ◽  
Principal Axes ◽  
Angle Difference

This study aims to investigate the effect of consolidation shear stress magnitude on the shear behaviour and non-coaxiality of soils. In previous drained bi-directional simple shear test on Leighton Buzzard sand, it is showed that the level of non-coaxiality, which is indicated by the angle difference between the principal axes of stresses and the corresponding principal axes of strain rate tensors, is increased by increasing angle difference between the direction of consolidation shear stress and secondary shearing. This paper further investigated the relation and includes results with higher consolidation shear stresses. Results agree with the previous relation, and further showed that increasing consolidation shear stresses decreased the level of non-coaxiality in tests with angle difference between 0° and 90°, and increased the level of non-coaxiality in tests with angle difference between 90° and 180°.

Measurement of soil strength in simple shear tests

1991 ◽  
Vol 28 (2) ◽  
pp. 255-262 ◽  
Author(s):  
J. H. Atkinson ◽  
W. H. W. Lau ◽  
J. J. M. Powell
Keyword(s):  
Simple Shear ◽  
Shear Test ◽  
Triaxial Tests ◽  
Shear Stresses ◽  
Shear Tests ◽  
Laboratory Equipment ◽  
Simple Shear Test ◽  
Failure Envelopes ◽  
London Clay ◽  
Normal And Shear Stresses

During a simple shear test the axes of stress rotate and, in a conventional apparatus in which the only stresses measured are the normal and shear stresses on horizontal planes, it is not possible to define the stress state completely. As a result, the measured failure stresses may not represent the true strength of the soil. Examination of possible Mohr's circles for soils at failure in simple shear tests demonstrates that the measured strength for a given soil depends on, among other things, the ratio of the horizontal and vertical effective stresses at failure. Results of laboratory tests on Cowden Till and on blue London Clay show the differences between strengths measured in simple shear and triaxial tests. A consequence of the conventional interpretation of the simple shear test is that effective stress failure envelopes have a false cohesion intercept with friction angles smaller than those measured in triaxial tests. Key words: clays, laboratory equipment, shear strength, shear tests, triaxial tests.

Stress Conditions in NGI Simple Shear Test

1972 ◽  
Vol 98 (1) ◽  
pp. 155-160
Author(s):  
A. Stanley Lucks ◽  
John T. Christian ◽  
Gregg E. Brandow ◽  
Kaare Höeg
Keyword(s):  
Simple Shear ◽  
Shear Test ◽  
Stress Conditions ◽  
Simple Shear Test

scholarly journals Strain Rate Dependent Behavior of Vinyl Nitrile Helmet Foam in Compression and Combined Compression and Shear

2020 ◽  
Vol 10 (22) ◽  
pp. 8286
Author(s):  
Nicolas Bailly ◽  
Yvan Petit ◽  
Jean-Michel Desrosier ◽  
Olivier Laperriere ◽  
Simon Langlois ◽  
...  
Keyword(s):  
Strain Rate ◽  
Shear Loading ◽  
Combined Loading ◽  
Impact Behavior ◽  
Rate Variation ◽  
Shear Stresses ◽  
Absorbed Energy ◽  
Static Compression ◽  
Rate Dependent ◽  
Dependent Behavior

Vinyl nitrile foams are polymeric closed-cell foam commonly used for energy absorption in helmets. However, their impact behavior has never been described in isolation. This study aims to characterize the strain rate dependent behavior of three VN foams in compression and combined compression and shear. Vinyl nitrile samples of density 97.5, 125, and 183 kg/m3 were submitted to quasi-static compression (0.01 s−1) and impacts in compression and combined compression and shear (loading direction of 45°). For impacts, a drop test rig was used, and a method was developed to account for strain rate variation during impactor deceleration. Young’s modulus and stress at plateau were correlated with foam density in both compression and combined loading. Vinyl nitrile foams were strain rate dependent: The absorbed energy at the onset of densification was two to four times higher at 100 s−1 than at 0.01 s−1. In combined loading, the compressive stress at yield was reduced by 43% at a high strain rate. Compared to expanded polypropylene, vinyl nitrile foams transmitted less stress at the onset of densification for equivalent absorbed energy and presented a larger ratio between the compression and shear stresses in combined loading (0.37 at yield). This larger ratio between the compression and shear stresses might explain why vinyl nitrile helmet liners are thought to be better at reducing head rotational acceleration than expanded polypropylene helmet liners.

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