Terramechanics Lab Tests
AScience provides the service of performing terramechanics lab tests for calibrating soil terramechanics models used in ground vehicle mobility application. The tests are typically performed at 3-10 soil moisture contents. Also, if desired the tests can also be performed at different temperatures from below freezing to 40 C. The customer provides samples 3-5 buckets of the desired soil. The soil tests are:
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Hydrostatic compression test.
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Unconfined shear test.
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Flat plate and cone penetrometer tests.
Tests 2 and 3 are performed at different soil pre-compaction levels in order to measure the soil shear strength friction and cohesion) as a function of soil pre-compaction levels. The terramechanics tests can be used to calibrate the Discrete Element (NG-NRMM complex terramechanics) and the height-field (NG-NRMM simple terramechanics) IVRESS's terramechanics models.
Terramechanics Tests Description
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Hydrostatic compression test. This test is used to measure the following soil mechanical properties:
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Plastic strain vs hydrostatic pressure.
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Elastic strain vs hydrostatic pressure.
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Bulk density vs hydrostatic pressure.
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Unconfined shear test. This test measures the soil shear strength as a function of shear displacement (with a slow shear speed) at a constant normal stress for a certain pre-compaction normal stress. The maximum shear strength is extracted from this test. The test is repeated for different values of normal stress and pre-compaction normal stress. The maximum shear strength is plotted vs applied normal stress and pre-compaction normal stress. Typically 20-30 unconfined shear tests are needed to generate this graph. From this graph the soil friction angle and cohesive strength can be extracted for each soil pre-compaction stress value.
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Plate and cone penetrometer tests. Cone and disk penetrometers with different diameters are used. In each test we plot the penetrometer vertical stress vs sinkage at different values of soil normal pre-stress.
Hydrostatic compression test device
Hydrostatic compression test simulation
