Skip to main content

Extremely high g-forces in impact analysis-abaqus explicit

Submitted by bharathsf on

Hi,

I have modeled a crash analysis of an Unmanned air vehicle on a rigid ground in abaqus explicit. I took the vertical velocity of the UAV as 700 mm/s (0.7 m/s) and the horizontal velocity 12000 mm/s. I want to find the g-force at the point of impact as soon as the impact takes place. The problem is when i plotted spatial acceleration vs time graph in abaqus to find out the g-force I am getting deceleration of the order of 0.22x10^9 mm/s^2 at the time of impact and the g-force is 22000 which I am sure is a very high value..i dont know what exactly is the problem..I have plotted spatial acceleration (vertical component-y axis in my case) A2 vs time. Is there any other option for the acceleration or am i making a mistake in taking the units of acceleration in the graph?

I have taken the units while modelling as 

Length-mm

time-s

Mass-Tonne

Density-tonne/mm^3.



Please help



Bharat

Forums
Ask iMechanica
Marcus Rademacher

You might try filtering the curve with a SAE General filter at 60 Hz. That's often used in automotive crash. The issue is that the choice of filter frequency will directly affect the peak acceleration value, so you could try a couple of different frequencies and see which make sense. It'd be best if you have something to validate against, such as an experiment. Also note that the ground being rigid will exaggerate the acceleration, since in reality the ground would absorb some of the energy.

The SAE General filter is available in Abaqus/Viewer. 

My Company - Red Cedar Technology

Wed, 04/17/2013 - 12:55 Permalink