Copied from NWTOYS.com Member: tcmaboy
Not my work all his ^
Carried over from WATTORA
The following are stress analyses of various slider mounting methods. This does not address any specific design, but rather general concepts.
Modeling was done in SolidWorks and analysis was done using COSMOSWorks. It was assumed that all parts are welded so solid bodies, not assemblies, were modeled. The material specified was mild steel.
It was assumed that the largest loading a slider will experience is a vertical load as a result of a truck sliding off an obstacle and impacting an object. The load applied in the model is based on an assumption that the load is distributed among many mounting legs. To simplify modeling a single leg was simulated and an appropriate fraction of the load was applied.
Method 1: Diamond shaped plates.
The slider is mounted using a diamond shaped plate attached to the outer wall of the frame rail. This method places the welds at 45 degree angles to the frame which allows the load to be spread over all of the welded surfaces. Each welded side will experience less stress, however there is a large stress concentration at the upper and lower corners of the plate.
Method 2: Square shaped plates.
The slider is mounted with a square plate to the outer wall of the frame rail. With this method only two of the four weld surfaces will be placed under a load. Each individual weld will experience higher loading, however the stress concentration that results from the diamond mounting method is eliminated and the peak loading that the plate experiences is lower than the peak loading that results at the corners of the diamond method.
Method 3: Leg through frame.
A hole is drilled through both walls of the frame and the leg is inserted and welded to both walls. This method spreads the load across both walls of the frame. Spreading the load over a larger portion of the frame significantly lowers the stress at any given point in the frame walls. With this method there are no sharp corners that result in stress concentrations.
Rounding off corners will reduce the stress concentration at that point. The larger the radius the greater the reduction in stress.
Mounting methods that include both walls of the frame are preferable to those that only use the outside wall.
Larger plates will spread the load over a larger area.
Gusseting the legs will reduce the stress at the base of the leg where it meets the mounting point. The load will be transfered to the point where the gusset meets the frame.