Study the Analysis of Stresses in Connecting Rod

Journal of Mechanical Engineering Research and Developments

ISSN: 1024-1752

CODEN: JERDFO

Vol. 43, No. 3, pp. 154-163

Published Year 2020

154

Study the Analysis of Stresses in Connecting Rod

Nuha Hadi Jasim Al Hasan

University of Basrah – College of engineering – Department of Materials Engineering

E-mail: [email protected]

ABSTRACT: Oil motors utilized gathering of quantities of associated connecting rods, the interfacing of

connecting rods function as changing over responding movement into revolving movement of the cylinder and

crankshaft, so it is important completing a complete research about slider-wrench system as a result of high

costly fix and substitution of these parts and their impact on different parts like chamber square and cylinder. In

this research varieties of tensile with compressive forces effecting on connecting rod analyzed at various

angular velocities were done. Cero PTC software was used in order to simulation stress distribution at static

condition in connecting rod.

KEYWORDS: simulation stress; connecting rod; stress analysis; Cero PTC 3.0

INTRODUCTION

The plain associating bar is the most regular in car application, it is interfacing cylinder to crankshaft for

pivoting it, transmitting the push of the cylinder to the crankshaft. The function of all connecting rod in

combustion engine subjected to high cycling loading which required to fit crankshaft and piston [1]. Shenoy PS

and Fatemi A. [2] optimized the weight of connecting rod under dynamic tensile and static compressive forces,

they found that the shank region giving greater reduction in weight of connecting rod. Takemasu T and

Vazquez V, Painter [3], used 3D finite element in order to simulate, the number of force allowance at 108 cycle

increase as decrease in stress concentration factor. Connecting rod with flash forging by DEFORM 3D for

reducing cost in forging manufacturing. Mirehei A, et. al.,[4] investigated the fatigue of connecting rod through

ANSYS to estimated lifespan. Vegi LK and Vegi VG. [5], Created the model of connecting rod by CATIA and

analyzed using ANSYS. The mainly deformation of connecting rod was bending under critical loading due to

buckling. Abhinav Gautam K and Ajit P. [6], developed the model of connecting rod to simulation static stress

using finite element by ANSYS, found that the failure appear at area close to root. Anusha B and Reddy CV.

[7], used ANSYS simulate stress at static condition, where he found the stress is maximum in piston end, that

from work safe design under giving loading condition. Shaari MS et. al. [8], they concluded that the optimized

material approach of connecting rod must be consider in the future work.

METHOD AND CALCULATIONS

Materials Used

One type of steel used is plain carbon steel AISI 1040 which manufacture of as-forged connecting rods. The

properties of annealed plain carbon steel AISI 1040 which are used in the present research shown in table 1.

Table 1. The characteristics of material considers in the simulation

Parameter Annealed plain carbon steel AISI

1040

Ultimate tensile strength (MPa) 475

Young’s modulus (GPa) 208

Poisson’s ratio 0.285

Coefficient of thermal expansion, C-1 1.05e-05

Density (g/cm3) 7.8

mailto:[email protected]


155

Theoretical Calculations

After designing connecting rod as a solid model which is use in engine of gasoline as seeing in Fig. 1,

constructed and analyzed by Cero PTC programming, it very well may be utilized for further procedure and for

that, powers or forces should be determined.

Figure 1. Solid design of assembly connecting rod design by Cero PTC 3.0

The maximum of compressive force which is affecting on the connecting rod calculated depended on peak

firing pressure, while maximum tensile force determined by effect of inertia masses at both the ends, see Fig. 2,

equations:

∅ = 𝑎𝑟𝑐sin[𝑅

𝐿𝑠𝑖𝑛𝜃] ……………….(1)

𝑟 = 𝑅𝑐𝑜𝑠𝜃 + 𝐿𝑐𝑜𝑠∅ ………………(2)

Figure 2. The forces effecting on Connecting Rod

(Vel) and (Acc) calculated using equations below,

𝐿𝑉𝑒𝑙 =𝑅

𝐿× 𝜔 ×

𝑐𝑜𝑠𝜃

𝑐𝑜𝑠∅ …………..(3)

𝑉𝑒𝑙 = −𝑅 × 𝑠𝑖𝑛𝜃 × (𝜔 + 𝐿𝑉𝑒𝑙) ………….(4)

𝐿𝑎𝑐𝑐 =(−𝑅×𝜔2×𝑠𝑖𝑛𝜃)+(𝐿×𝐿𝑉𝑒𝑙2×𝑠𝑖𝑛∅)

𝐿×𝑐𝑜𝑠∅ …………….(5)


156

𝐴𝑐𝑐 = −𝑅 × 𝜔 × 𝑐𝑜𝑠𝜃(𝜔 + 𝐿𝑉𝑒𝑙) − 𝑅 × 𝑠𝑖𝑛𝜃 × 𝐿𝐴𝑐𝑐 …………..(6)

𝐹𝑜𝑟𝑐𝑒 =𝜔×𝐴𝑐𝑐

110×𝑐𝑜𝑠∅ ………………(7)

Where :

r : the radius crank, r equals to piston stroke / 2

𝜃 : the angle of crank at dead center.

: connecting rod angle at horizontal.

L: Connecting rod length, L equal to twice times of the stroke.

ω : angular velocity (rad/s).

Vel : piston velocity, LVel : angular velocity (rad/s),

Acc : piston acceleration, and LAcc : angular acceleration (rad/s2).

BOUNDARY CONDITIONS FOR FINITE ELEMENT DETERMINATIN OF CONNECTING ROD

Cero PTC 3.0 software’s apply by the following considerations to measure the stresses which were effected on

parts which is considering in connecting rod model : All node on surface in the translations coordinates X, Y,

and Z are put to zero when connecting rod in tension, and so that when the it expose to compressive axial

force, 120o angle contact surface is totally restrained, In order to plot slider crank output put the crank angle

variation from 0 to 360 degree as x-axis, and set displacement data results and rod force as y-axis as resulted in

Table 1.

Different of three compression load are : -120.394, -3009.86, -20346.6N, and tensile load are: 200.6573,

5016.433, 33911.94N, affecting on connecting rod, these resulted values illustrated in table 2. and figure 3.

Figure 3. Force displacement mechanism in connecting rods


157

Table 2. Force in the connecting rod results

Input R, L, and strok set values of 36.775mm, 147.1mm, and 73.55 mm respectively

crank angle at 3250rpm

r lvel vel lacc Acc force theta phi

Degree Radians Radians

0 0 0 183.875

85.1190

5 0 0

-

5328883

33911.0

8

30 0.52381

0.25277

5

174.269

7

76.1253

8 -7663.06 -12631.9

-

4289418

28192.1

8

60

1.04761

9

0.44794

9

150.960

8

47.1837

3 -12349.2 -21758.4

-

1746650

12331.7

3

90

1.57142

9

0.52359

9

127.369

1 -0.06214 -12518.7 -25098.3 906233 -6659.08

120

2.09523

8

0.44759

8

114.194

7 -47.2792 -9333.22 -21742.7 2515781 -17759

150

2.61904

8

0.25220

9

110.578

8 -76.1698 -4851.06 -12604.5 3094218 -20333.8

180

3.14285

7 -0.00063 110.325 -85.119

11.8745

1 32.0654 3197330 -20346.6

210

3.66666

7 -0.25334

110.583

8 -76.0808

4873.98

7

12659.3

5 3092980 -20331.6

240

4.19047

6 -0.4483

114.230

6 -47.0882

9352.92

9

21774.1

2 2510901 -17730.5

270

4.71428

6 -0.5236

127.462

2

0.18642

4

12527.8

5

25098.2

5

895444.

8 -6579.81

300

5.23809

5 -0.44725 151.086

47.3744

8

12337.2

4 21726.9

-

1760448

12424.9

5

330

5.76190

5 -0.25164

174.357

7

76.2141

2

7631.10

8

12576.9

7

-

4298947

28246.5

7

360

6.28571

4

0.00126

4

183.874

8

85.1188

5 -39.5817 -64.1307

-

5328858

33910.9

4

crank angle, at 1250rpm



0 0 0 183.875 32.7381 0 0 -788297

5016.43

3

30 0.52381

0.25277

5

174.269

7 29.279 -2947.33 -1868.63 -634529

4170.44

2

60

1.04761

9

0.44794

9

150.960

8

18.1475

9 -4749.7 -3218.7 -258380

1824.22

1

90

1.57142

9

0.52359

9

127.369

1 -0.0239 -4814.89 -3712.77

134058.

2 -985.072

120

2.09523

8

0.44759

8

114.194

7 -18.1843 -3589.7 -3216.37 372157 -2627.07

150

2.61904

8

0.25220

9

110.578

8 -29.2961 -1865.79 -1864.56

457724.

7 -3007.95

180

3.14285

7 -0.00063 110.325 -32.7381

4.56712

1

4.74340

3

472977.

9 -3009.86

210

3.66666

7 -0.25334

110.583

8 -29.2619 1874.61

1872.68

5

457541.

6 -3007.63

240

4.19047

6 -0.4483

114.230

6 -18.1108

3597.28

1

3221.02

4

371435.

1 -2622.85

270

4.71428

6 -0.5236

127.462

2

0.07170

2

4818.40

3

3712.75

9

132462.

3 -973.345

300

5.23809

5 -0.44725 151.086

18.2209

6

4745.09

4

3214.03

9 -260421

1838.01

1

330

5.76190

5 -0.25164

174.357

7

29.3131

2

2935.04

2

1860.49

9 -635939

4178.48

8


158

360

6.28571

4

0.00126

4

183.874

8

32.7380

2 -15.2237 -9.4868 -788293

5016.41

3

crank angle, at 250rpm



0 0 0 183.875 6.54762 0 0 -31531.9

200.657

3

30 0.52381

0.25277

5

174.269

7

5.85579

9 -589.466 -74.745 -25381.2

166.817

7

60

1.04761

9

0.44794

9

150.960

8

3.62951

8 -949.941 -128.748 -10335.2

72.9688

3

90

1.57142

9

0.52359

9

127.369

1 -0.00478 -962.979 -148.511

5362.32

7 -39.4029

120

2.09523

8

0.44759

8

114.194

7 -3.63686 -717.94 -128.655

14886.2

8 -105.083

150

2.61904

8

0.25220

9

110.578

8 -5.85922 -373.159 -74.5826

18308.9

9 -120.318

180

3.14285

7 -0.00063 110.325 -6.54762

0.91342

4

0.18973

6

18919.1

1 -120.394

210

3.66666

7 -0.25334

110.583

8 -5.85237

374.922

1

74.9073

9

18301.6

6 -120.305

240

4.19047

6 -0.4483

114.230

6 -3.62217

719.456

1 128.841 14857.4 -104.914

270

4.71428

6 -0.5236

127.462

2 0.01434

963.680

5

148.510

4

5298.49

1 -38.9338

300

5.23809

5 -0.44725 151.086

3.64419

1

949.018

9

128.561

5 -10416.9

73.5204

4

330

5.76190

5 -0.25164

174.357

7

5.86262

5

587.008

4

74.4199

7 -25437.6

167.139

5

360

6.28571

4

0.00126

4

183.874

8

6.54760

4 -3.04474 -0.37947 -31531.7

200.656

5

At 3250 rpm , keeping fixing the small end (at pin end ) in static analysis and tensile load of 33911.94N is

applied at bigger end (crank end ) apply, then Keeping fixing the small end (at pin end ) in static analysis and

compressive load of -20346.6N is applied at bigger end (crank end ) apply, see figures 4.

(a) Tension (b) Compression

Figure 4. Boundary conditions for finite element analysis in connecting rods


159

RESULT AND DISCUSSION

The modeling design of assembly connecting rod shown in Fig. (1), is accomplished in Cero PTC 3.0 program

with finite element technique used to stresses analyze. Since the connecting rod included surfaces and many

merging radii, therefore there are limitations to old style ponder into this issue and a limited component

investigation is increasingly reasonable to look into on the impact of consolidated burdens results from gas

pressure, oscillating parts of an engine and inertia of reciprocating.

In order to finite element analyzer mesh is auto generation in the solid of connecting rod, by tetrahedral

elements with various component lengths of cross section as show in Fig.(5), where there are huge edge of

material evacuation in the connecting area to small end of connecting rod and all very small end area.

Figure 5. Mesh result by auto generation of connecting rod

After simulated the solid part of connecting rod by using the boundary condition mention in item 3, the

distribution of stresses in item on Von Mises theory and principal stresses result, shown in figures from 6 to 11,

it can be observed that at high angular velocity effect of 3250 rpm , when tensile load effect at static condition,

the Von Mises stresses distribution greater than the effect of compressive load while the principal stresses

distribution is less as shown in figures 6 and 7.

At medium and low angular velocities (1250 and 250 rpm), the Von Mises stresses distribution is the same

results in the case of tensile and compressive loads exerted load as shown in figures from 8 to 11.

(a) Von Mises stresses (b) Principle stresses


160

Figure 6. Stresses distribution with pin end fixed and static tensile force 33911.94N at crank end at

3250rpm.


Figure 7. Stresses distribution with pin end fixed and static compressive force -20346.6N at crank end at

3250rpm.



161

Figure 8. Stresses distribution with pin end fixed and static tensile force 5016.433N at crank end at

1250rpm.


Figure 9. Stresses distribution with pin end fixed and static compressive force -3009.86 N at crank end at

1250rpm.



162

Figure 10. Stresses distribution stresses with pin end fixed and static tensile force 200.6573N at crank end at

250rpm.


Figure 11. Stresses distribution with pin end fixed and static compressive force -120.394N at crank end at

250rpm

CONCLUSION

First 3D modulating of connecting rod was draw, and simulation done with that heap examination was

performed utilizing Cero PTC programming.

The accompanying end aftereffects of this investigation

1. There is huge edge of material expulsion from huge end territory, little end zone and region

associating with little end the of interfacing accordingly from FEA examination

2. The result of stresses at variations of angular velocities were shown in table 2.

Table 2. Maximum tensile and compressive force related to angular velocity.

Angular velocity, rpm 250 1250 3250

Maximum tensile force, N 200.6573 5016.433 33911.94

Maximum compressive force, N -120.394 -3009.86 -20346.6


163

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Study the Analysis of Stresses in Connecting Rod