Industrial Engineering Assignment-Engineering Research paper on connecting rod

Summary On:
DESIGN OF CONNECTING ROD OF INTERNAL COMBUSTION ENGINE:
A TOPOLOGY OPTIMIZATION APPROACH
M.S. Shaari  , M.M. Rahman , M.M. Noor , K. Kadirgama  and A.K. Amirruddin
Faculty of Mechanical Engineering, Universiti Malaysia Pahang
26600 UMP, Pekan, Kuantan, Pahang, Malaysia
Phone: +6094242246, Fax: +609-4242202
E-mail: shamilshaari@yahoo.com; mustafizur@ump.edu.my
Automotive Engineering Centre, Universiti Malaysia Pahang

Introduction

This paper presents the design connecting rod of internal combustion engine using the
topology optimization.
The objectives of this paper are to develop structural modeling,finite element analyze and the optimization of the connecting rod for robust design.

The topology optimization technique is used to achieve the objectives of optimization which is to reduce the weight of the connecting rod.

Optimization Approach

The objective of optimization technique is to minimize the mass of the connecting rod
and reduce the cost of production. The connecting rod subjected to tensile load at crank
end, while using factor of safety 3 as recommended by Shenoy (2004). The maximum
stress of the connecting rod monitored and make sure it is not over the allowable stress.
The load of the connecting rod optimized is comprised of the tensile load of 26.7 kN at
crank end. Linear buckling analysis was performed on the connecting is 26.7 kN. The
buckling load factor is considered also 3. The optimization technique methodology
flowchart is shown in Figure 1.

The Steps involved is as follows:

1. The initial design is compared to other design before performing the optimization.
2. A simple three-dimensional model of connecting rod was developed using SOLIDWORKS software and finite element model was created using TET10.
3. Mesh study was performed on the FE model to ensure sufficiently fines sizes are employed for accuracy of the calculated result depends on the CPU time.
4. FEA for both tensile and compressive loads were conducted. Two cases were analyzed for each case, Firstly, load applied at the crank end and restrained at the piston pin end, and secondly, load applied at the piston pin end and restrained at the crank end and the axial load was 26.7 kN in both tension and compression.

Optimization of connecting rod.

The optimization of the connecting rod carried out using topology optimization

technique. The optimization focused on the uncritical sections which need to be

reduced. From the topology optimization, it is suggest the unnecessary shape and design

of the connecting rod.  The main objective is to minimize the weight

of the connecting rod as well as the total production cost. It can be seen that the

optimized model is reduce the weight from initial design until the value converges.

Figure 8 shows the objective function history of the optimization. The convergence of

the design is immediately after cycle no. 9. The implementation of these optimizations

is to find out the best design and topology of the connecting rod to improve the

performance and the strength especially at the critical location. The possible

modification section of the optimized connecting rod is indicated in the figure. The

section with lower value than initial value considered as the suggestion to be optimized

in the new design. Table 4 shows the comparison between initial and optimize designs

on max principles stress and mass of the connecting rod. The optimize connecting rod

no 4 was choose as the best optimize design due to the lowest occurred stress and mass.

Even though the mass of the optimize connecting rod is not the lowest, but the decision

was also based on the maximum stress which is 320 MPa. 

The new design of the connecting rod and mass of the connecting rod is 0.464 kg compare to

initial design 0.577 kg which is 11.7% lighter.

CONCLUSION

The modeling of connecting rod and FE Analysis has been presented. Topology

optimization were analyzed to the connecting rod and according to the results, it can be

concluded that the weight of optimized design is 11.7% lighter and maximum stress

also predicted lower than the initial design of connecting rod. The results clearly

indicate that the new design much lighter and has more strength than initial design of

connecting rod. Material optimization approach will be considered for future research