ANALYSIS FOR ROLL CAGE OF ATV
To properly approximate the loading that the vehicle will see an analysis of the impact loading seen in various types of accidents was required. To properly model the impact forces, the deceleration of the after impact needs to be found. To approximate the worst case scenario that the vehicle will see, research into the forces the human body can endure was done. It was found that human body will pass out at loads much higher than 7G. And the crash pulse scenario standards set by industry is 0.15 to 0.3 sec. We considered this to be around 2. 5 sec. It is assumed that worst case collision will be seen when the vehicle runs into stationary object.
FRONTAL IMPACT ANALYSIS-
In this case we assumed a force of 4000lbf.Front members of the roll cage was constrained DOF=0 and then assumed force was uniformly distributed over RRH in the direction of collision.
Fig 05 : Front Impact-Deformation Fig 06 : Front Impact-stress
Figure 7 : RRH
Fig 06: Constraints
ROLL OVER ANALYSIS-
For roll over a force of around 1500lbf was considered to be acting along three axis having components 1200lbf, 800lbf and 400lbf to generate real roll over scenario.
The force used for the roll over analysis is dependent on the height of the drop. The purpose of the roll over analysis is simply to rate the frame for a certain drop height. The starting point will be a ten for drop. The force used to analyze the frame at that height is gathered using data from “The Motor Insurance Repair Research Centre.” *5+ A impact velocity can be calculated using Equation 4. That impact velocity is then used to interpolate an impact acceleration and pulse using data from “The Motor Insurance Repair Research Centre.” *5+
Fig 08: Roll over-Deformation Fig 09: Roll over -stress
SIDE IMPACT ANALYSIS-
For this 50% of the front impact forces were considered to be acting inwards at certain angle. So we applied forces 1500lbf, 1000lbf and 1000lbf in three directions.
Figure 10: Side Impact deformation Figure 11: Side Impact Stress
Table 2: chassis Analysis Result
Table 3: Chassis Analysis Result
Figure 12: Torsional Rigidity
Figure 13: Front Wheel Bump
Figure 14: Drop Test