Recent content by assafwei

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    How much deceleration is reasonable for a free fall impact?

    Thanks, if this is true for rigid objects, than 200G seems logical in my case.
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    How much deceleration is reasonable for a free fall impact?

    Sure, forgot to state - ground is infinitely rigid. Any other information missing?
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    How much deceleration is reasonable for a free fall impact?

    1. The velocity at contact is the boundary condition for the simulation (to reduce simulation time). 2. Calculating deceleration to zero is problematic since there is a lot of warping and the body isn't rigid, so hand calculations will be very rough, but I will try this and see if I get...
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    How much deceleration is reasonable for a free fall impact?

    Hi, Hope this is the correct forum for this kind of question. I am doing an explicit finite elements simulation of a tank, weighs around 7.5 Kg with internal parts, falls from 1 meter. Since I never had a validation of such an experiment I am trying to understand if the numbers are right. I...
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    Initial yield stress Vs. tensile strength

    I will be happy if you could give me some pointers instead of riddles... I will also be happy if you could explain how did you come to think that I don't understand/know the general concepts of the stress/strain curve. Please understand - I don't pretend that I do understand the concept fully...
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    Initial yield stress Vs. tensile strength

    So, Is "initial yield strength" the same as "yield strength"? Currently I get good results when using the "yield strength" as the "initial yield strength" in the FEA software (Femap) so I guess its the same, but could someone please shed a light on the subject? Thanks.
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    Initial yield stress Vs. tensile strength

    Let me rephrase (made some mess with the terms): Usually I get the tensile stress at yield (or yield strength). I need the initial yield strength, are they the same? or is the initial yield the end of the elastic portion of the curve? Forgot to mention that I am dealing with plastics, so the...
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    Initial yield stress Vs. tensile strength

    Are those the same? if not, how do I calculate the initial yield stress from the tensile strength? all the materials properties I see on the web only specify tensile strength, and I need the initial yield stress as an input on non-linear FEA analysis. Is it possible to extract the initial yield...
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    Solidworks COSMOS - How to read results

    I returned to the textbook and realized I was really wrong. Thanks for the replies it really helped.
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    Solidworks COSMOS - How to read results

    Thanks for the reply, I meant the other stress criterions, Since I know shear is the critical parameter, I check all three shear parameters, but than how should I consider the normal stresses in the points where the shear is at maximum, do they increase or decrease the stresses on the...
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    Solidworks COSMOS - How to read results

    Hi, First of all I must say, I am a bit ashamed asking this question... Since its been a long time since I studied mechanics of materials and since I never used it in my line of work, I am trying to analyze a problem regarding this subject using COSMOS in solidworks, I have a model and I...
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    Need help understanding an equation

    Hi, Im reading an article (The meaning of einstein's equation : http://math.ucr.edu/home/baez/einstein/node6a.html" ) and can't understand the development of one of the equations, the equation is attached as an image, I can't understand the transition from the left side of the equation to...
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    Converting potential energy to force

    Unfortunbatley i don't have the equipment to measure the deflection so this method is not applicable
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    Converting potential energy to force

    From what i understood, you propose to calculate the deflection using your equation and then extract the force using regular beam deflection equations? This could be feasble assumin I am trying to figure out the force exerted on a beam, unfortunatley this is not the case... I was pretty sure...
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    Converting potential energy to force

    Hi, I have an impact test (Metal ball falling on plastic) and i have a problem conveting the energy (i.e. height and mass) to the force apllied to the plastic upon impact. I tried calculating with impact formulas but its difficult to estimate the time interval of the impact. I tried...
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