I am wanting to find a good, reliable(virus free) and free, car crash simulating software…
1st. scenario: What I am tring to figure out is the cone of trajectory of an unsecured metal patio table(weighing approx 50-100 ibs), in the bed of a pickup truck that is traveling at approx. 60-70 MPH, in the far right lane, on a 3 lane interstate? Would the table fall off directly behind the pickup truck, in the middle lane or in the far left lane?
2nd. scenario: if the patio table flew off the pickup truck, onto the same lane or perhaps the middle lane and THEN was run over by a semi truck(18 wheeler), what would then would the trajectory point(s)?
An answer is qreatly appreciated with possible links or mathmatical formula, to back the findings.
thanks
MS 
I can’t imagine being able to get a useful simulation with so many variables: the shape of the table, the weight distribution between the top and the legs, the height of the table (was it higher than the top of the cab?), crosswinds, turbulence from passing big trucks, type of tailgate (none, solid, slatted…), position of table (against cab, against tailgate), bumpiness of ride (good tires, old tires, rough road…), lateral force (straight road or going around a bend?), exact weight (there’s a big difference between 50 lbs and 100 lbs), type of table top (metal mesh, solid glass).
Might as well roll some dice.
Concur. And the best rule of thumb to apply is Mr Newton. Things tend to continue what they’re doing, absent a compelling reason to do otherwise. A heavy table top is going to try to continue moving in a straight line when the vehicle carrying it stops. If the things in the way of the tabletop are flimsy, it will smash through them. If they’re tough, it will smash into them and cause damage
I do this kind of simulation (or something akin to it, anyway, with aerospace structures) and I can assure you that there is no “good, reliable(virus free) and free, car crash simulating software”.
There are codes such as LS-Dyna, Radioss, Abaqus/Explicit, Dytran that can do the dynamic structural deformation simulation using the finite element method (which is what is generally meant by “crash simulation”). There are multi-body dynamics codes such as ADAMS, DADS, SIMPACK, and MotionSolve that perform mechanics simulation of rigid or pseudo-deformable bodies with perturbations. And there are fluid dynamics tools such as Fluent, FLUIDYN, and CFD++ that perform computational fluid dynamics. These tools cost tens of thousands of dollars a year to lease. Some vendors will sell you a short-term token based upon runtime or usage, but at a premium. There are free types of all of these simulation tools, but they are usually buggy, poorly documented, or more frequently, both.
To set up and run a real-world problem such as you describe in any of these tools individually requires several years of experience. Running a coupled fluid/structural/high displacement model as you describe would challenge be challenging to a team of professional analysts. For instance, setting up a relatively simple problem involving a bolt severing device took one professional analyst about two months before he got results that looked real, and this is a single function cartridge actuated device with highly constrained dynamics.
A more typical approach–one that we use in guidance and control simulation, for instance–would be to make a simplified state model of the table and other elements of the system with a defined set of parameters and tolerances, and then run a “Monte Carlo” simulation in which the parameters are varied (perturbed) randomly across defined distributions (usually Gaussian or constant) and then run hundreds or thousands of times to capture the sensitivity and stability of the system. However, this assumes that you have significant a priori understanding of the system being simulated, through test or service data. If you set up such a simulation, but fail to include a parameter for some important characteristic that influences the behavior of the system, your simulation will be worthless.
I point out all of this not to provide a tutorial on dynamic simulation, but to try to give a flavor for how complicated the problem is. It isn’t something a novice is going to work out in a few spare evenings.
Stranger