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 Topic: Piling Subject: modeling of planetary underground tool
 Author: Nicole 2005-08-10 As I am a mechanical engineer, I am a complete newbie on the field of geotechnical engineering.Now I would like to do a numerical simulation of a planetary underground tool(a mobile penetrometer) for planetary exploration (mars missions). The soil on the respective location on mars can be understand as a mixture of dry sand and clay.The underground tool consists of a cylindrical body with a cone at its top. The system is driven by a single electric motor/planetary gear compressing a force spring. Upon release of the spring two adjoining masses are accelerated into opposite directions. For forward hammering, one of the two masses impacts again the casing front tip from the inside. A part of this energy is dissipated due to internal friction processes whereas the usable fraction of the shock energy causes a displacement and compression of the soil. So the two important effects to be simulated are friction (inner friction of casing/hammering mechanism and outer friction casing/soil) and shock processes.My questions:I am searching for a program able to simulate both mechanical (springs, motor, etc.)and geology effects (soil). At least I need to simulate the elastic/plastic effects of diplacement/compression, the resistive forces of the soil against the penetrating object and the skin friction penetrator/soil. Also it would be useful to be able to simulate a possible hole collapse. Does anybody know a program that is able to do this? And do you have an advice how to simulate the soil without having to model the behaviour of every single grain(maybe as a flexible body or a fluid)? Furthermore I have problems to find information about the elastic properties of DRY clay (for modeling the mars soil).I read something about poisson`s ratio between 0,35 and 0,4 for clay, but which value do I have to calculate with for dry clay? And what about dry sand?Thanks in advance for your help! Reply to this posting
Follow-up:
 Author: evabine 2005-08-17 I think there is no such program, which can simulate all this you describe. The best choise for that may be FLAC or FLAC3D (based on finite difference method). I suggest to find an expert for that sort of simulation. It is very hard to simulate something like that. Poisson ratio is one of parameters, which describes the soil or rock material. The others are elastic modulus, cohesion, friction angle, specific weight....best regardsjure