Toyota Conrod & Piston FEA

Two simulations were conducted on the connecting rod to simulate an ignition stroke and the exhaust stroke of a typical ICE.

 To simulate the ignition stroke, a compressive load path was created. This was done by placing a 120 degree bearing load on the small end of the connecting rod. This 120 degree load was created by creating a split line on the bottom half of the small end bore diameter, creating two 60 degree sections, and placing the bearing load on that surface. The big end was then fixed to simplify the simulation so that I could just simulate the small end under the compressive load. 

As pictured below (Figure 1a), the maximum displacement under such load is at the top of the small end, with an approximate value of 1.4e-4 mm of displacement. As you go down the connecting rod, the displacement of the connecting rod gets much smaller. 

In terms of stresses (Figure 1b), the maximum von Mises stress is concentrated at the bottom of the small end bore, directly where the compressive load was placed. The maximum von Mises stress value is 8.397e1 psi. The von Mises stresses dissipate down the shaft of the connecting rod towards the big end. 

To simulate the exhaust stroke, a tensile load path was created. This was done by placing a bearing load on the small end of the connecting rod. This load was created by splitting the top half of the small end bore diameter equally and placing the bearing load on that surface. The big end was then fixed to simplify the simulation so that I could just simulate the small end under the tensile load. 

As pictured below (Figure 2a), the maximum displacement under such load is at the top of the small end, with an approximate value of 0.36 mm of displacement. As you go down the connecting rod, the displacement of the connecting rod gets disappates more efficiently compared to the compressive load. 

In terms of stresses (Figure 2b), the maximum von Mises stress is concentrated at the sides of the small end bore, directly where the compressive load was placed. The maximum von Mises stress value is 2.84e5 psi. The von Mises stresses dissipate down the shaft of the connecting rod towards the big end, but are still notable at the filleted edges of the small end connecting to the shaft of the connecting rod. 

A simplified compressive load was simulated on the head of the piston to simulate the loads during the ignition stroke. During an ignition stroke, the forces acting on a piston is between 750 psi on the top of the piston. 

As shown below (Figure 3a), the von Mises stresses peaked on the center of the top of the piston, at around 2.8e+2 psi and also peaked around the sides of the piston. Figure 3b shows a cross-section of the piston with a deformation factor of 750 and indicates peak von Mises stresses at around 1.329e+3 psi around the joining fillets of the piston pin hole locations with the rest of the piston. The von Mises stresses are also relatively high around the inner joining of the sidewall to the top of the piston (Figure 3c).