Impact load history

[Abrar_1512]

I want to perform impact analysis of an aircraft to building. How to generate time history of applied impact force. Is there any method available to generate time history for impact force to be input in software. The mass of aircraft is 1000 tons velocity 5m/s and assumed distance before collision is 1m.

 

[bkal]

You might want to have a look at a paper by Riera: On the Stress Analysis of Structures Subjected to Aircraft Impact Forces. It is quite an old paper (from 1968 I thinks) but is a useful introduction to the problem.

 

[ldeem]

I have always done impact as an energy problem. Blodget has a discussion of this method.

The basic steps are:
1. Build analysis model of the building with several (4 or 5) load cases such that you can create a chart of force versus displacement. Force to be applied at point of impact. Plot this and the area under the curve will equal energy (force times distance). Plot will likely be linear.
2.Calculate the kinetic energy of the plane impact as 0.5*mass*velocity squared
3.Iterate until the energy absorption of the building equally kinetic energy of the plane. Once you have this you know the max load during impact. Now you need to evaluate the building at that load to make sure everything stays below yield. This method only works in the linear elastic range.

It is counterintuitive but making the structure more rigid typically worse. You end up with less displacement and very large forces.