I am working on chassis design of Hyperloop pod. We are using a tubular a space frame.
When brakes are applied at very high velocities like 100m/s, large amounts of forces will be acted on the chassis. I assume that braking forces are the maximum forces the chassis has to bear in its regular use and it will be the design criteria. Can you please elaborate on how to carry out analysis on chassis when brakes are applied using ANSYS?
Dear Siddharth Alampally, braking is basically 'negative' acceleration. Starting with Newton's equation of Motion the velocity v = vo + a_brake * t_brake. Assuming to brake from vo=100 m/s to Zero (v=0) you need about 10 sec, you have to achieve a negative acceleration of -10 m/s2. Cars of this type may have a dead weight of M=1000 kg plus. Hence the sum of deceleration Forces F_brake = M * a_brake would be in the range of 10 kNewton or more. Front wheel Brakes have to carry up to 80% or more of the total braking load and each front wheel brake takes half of this. So roughly 4 to 5 kN will work at each wheel. The rest depends on the design of wheel and brake Diameter a.s.o.
Rudiger Rentsch, thank you for the answer sir and yes, calculations are absolutely right.
So these forces acting on the wheels are transferred to the chassis. So I want to analyze the chassis when these forces are acting on it.
So what would be the right platform? Ansys static structural or ansys transient structural or ansys explicit dynamics? In each of the case, what would be the inputs constrains like, forces, velocities or fixed constrains to exactly replicate the real condition?
Siddharth
From my experience with racing, you need to look at it from two points: 1) Un-sprung, 2) suspended weights. The major stress will be at the points where the suspension arms connect to the chassis. That is, where un-sprung weight meets suspended weight. The amount of initial force will be limited by how much friction your tires will allow you. Assuming you used an initial deceleration of the aforementioned -10m/s^2, get the rho of the vehicle's weight times the deceleration. That will be distributed across the suspension connection points to the chassis. These forces are then transferred to the suspension arms and then the brakes as friction which in turn transfer the force to the tire/road surface interface. If you look at the suspension arm, you need to look at it as a lever. Use the force generated above to design the connection to the frame for how much stress it needs to take before it yields (bends, distorts). A bit of advise: design the connections at all four corners for the max load (vehicle with full payload) plus about 50% to accommodate brake application while cornering.
Hi , I have a very similar question to that of siddharth
I am working on a front loader attach with a step cycle , I trying to work out all the forces acting on the front loader which can withstand a maximum weight of 40 Kg .
I am looking for the best possible position to attach the front loader with the mechanical step cycle
Can anyone help me with the approach to look ahead in this research ?
Many thanks
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