rl-03 structural durability analysis of passenger car exhaust … · 2017-10-27 · structural...

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Simulation Driven Innovation

Structural Durability Analysis of Passenger Car Exhaust System using FPM Approach in Radioss

Dr. S. Rajadurai

Head- R&D Sharda Motor Industries Limited

Research and Development P-12,1st Avenue, Mahindra World City, Chengalpattu, Tamilnadu - 603002.

Suresh Natarajan Asst Manager- CAE

Sharda Motor Industries Limited Research and Development

P-12,1st Avenue, Mahindra World City, Chengalpattu, Tamilnadu - 603002.

Rahul. A Senior Engineer-CAE

Sharda Motor Industries Limited Research and Development

P-12,1st Avenue, Mahindra World City, Chengalpattu, Tamilnadu - 603002.

Abbreviations: CAE: Computer Aided Engineering, FPM: Fatigue Process Manager, UTS: Ultimate Tensile Strength, RLD: Road Load Data

Keywords: Exhaust System, Muffler, Resonator, Road Load, Hanger Bracket.

Abstract

This paper deals, to evaluate the durability of exhaust system components by CAE Simulation. Finite element simulation are carried out and the results are explained for the typical exhaust system components considering the durability loads such as engine vibration loading, proving ground road loads. The durability issues associated with the exhaust system components such as muffler-pipe system, brackets and hanger designs are analyzed. Detailed analysis of exhaust components are explained.

Finite element modelling is carried out for passenger car exhaust system using Altair's pre-processing tool HyperMesh. Static analysis is performed by using Radioss for exhaust components to determine the high stress region, followed by S-N approach for calculating the fatigue life of exhaust system components with the help of HyperWorks, Fatigue Process Manager (FPM) in Radioss. The results are viewed through Altair's post-processing tool HyperView. It is observed that this approach produces comparable results with simplified pre and post processing as well as reduction in solving time.

Introduction

Ever increasing demands for durability, lighter and cost effective designs of automotive products have lead to more frequent usage of powerful Numerical techniques for solving structural durability problems. In the automotive industry, the detection of structural durability failures has traditionally relied on proving ground durability tests. It is generally recognized that developing designs through testing & retesting using several prototypes is not helping in accelerating the product development. Hence virtual fatigue/durability calculations of automotive components have become an essential part for vehicle manufacturers. Hence designing the exhaust system for durability is extremely important. The automotive exhaust system Physical tests offer durability evaluation of all the exhaust system components. There are several different tests for validating the exhaust component designs under different loading conditions. For example, oscillating load test is used to test all welds under bending loads, the road load rig test is used to test the entire exhaust system and components under road and thermal loads, and engine dynamometer test is carried out under exhaust and thermal loads. The laboratory test offers durability evaluation for the exhaust system, which could provide pass/failure information. Comparing to laboratory tests, CAE is another tool, which could be employed for improving durability performance of exhaust components while reducing significant product development costs and time. CAE not only evaluate durability performance, but also explores many possible design options and promises to yield optimum design with significant experimental cost and time savings. Several examples of critical components and designs are considered in this paper to explain the durability issues involved in a typical exhaust system development cycle and how CAE


usage enabled in obtaining improved designs.performance in this paper. Some of the design elementsare:

1. Muffler - pipe system.

2. Hanger design.

3. Muffler Bracket design.

4. Resonator - pipe system.

Figure 1

[Note: The Images Shown Are Proprietary And Should Not Be Used, For Any Purpose, Without Prior Permission Of Sharda

Methodology:

The durability of the exhaust system submapped with sensor and load cell to acquire load data from the applied to the exhaust system subsensitive design area in the exhaust system components. Altair Hyperdurability of the exhaust system components.physical testing of the sub-systems. Thcost.

Fatigue Process Manager (FPM):

The S-N approach is suitable for high cycle fatigue, where the material is subject to cyclical stresses that are predominantly within the elastic range. more than 1000 cycles.

The S-N approach is based on elastic cyclic loading, inferring that the Snumbers greater than 1000 cycles. This ensures that no significant preferred to as high-cycle fatigue.


usage enabled in obtaining improved designs.FPM of Altair HyperWorks is used to predict the durability Some of the design elements of Exhaust system considered for the evaluation

Figure 1: Schematic Diagram Of Small Car Exhaust System

Note: The Images Shown Are Proprietary And Should Not Be Used, For Any Purpose, Without Prior Permission Of Sharda Motor Industries Limited.]

system sub-components is carried out with the RLDmapped with sensor and load cell to acquire load data from the road. Then the acquired applied to the exhaust system sub-components. A CAE simulation is carried out to adsensitive design area in the exhaust system components. Altair HyperWorks FPM is used to determine the durability of the exhaust system components. The methodology helps in virtual testing and to reduce

systems. This virtual testing using FPM will reduce the

Fatigue Process Manager (FPM):

N approach is suitable for high cycle fatigue, where the material is subject to cyclical stresses that are predominantly within the elastic range. Structures under such stress ranges should typically

N approach is based on elastic cyclic loading, inferring that the S-N curve should be confined to numbers greater than 1000 cycles. This ensures that no significant plasticity is occurring. This is commonly

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is used to predict the durability considered for the evaluation

Note: The Images Shown Are Proprietary And Should Not Be Used, For Any Purpose, Without Prior Permission Of Sharda

components is carried out with the RLD. The exhaust system is road. Then the acquired load data is

components. A CAE simulation is carried out to address fatigue orks FPM is used to determine the

The methodology helps in virtual testing and to reduce is virtual testing using FPM will reduce the development time and

N approach is suitable for high cycle fatigue, where the material is subject to cyclical stresses that Structures under such stress ranges should typically survive

N curve should be confined to lasticity is occurring. This is commonly

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The following steps are followed to evaluate fatigue life of the system with the S-N method through Fatigue Process Manager (FPM).

Muffler-Pipe System:

This CAE Simulation is designed to address fatigue sensitive design in the area of exhaust pipe entry into the forward end of a Muffler in a vehicle exhaust system. This CAE Simulation is used to evaluate the bending fatigue durability of the forward pipe entry of muffler. The muffler pipe system, considered in this case, have baffles and internal pipes whose diameter is slightly smaller than the pipes outside the muffler. Hence there is a transition zone in the muffler inside pipe. A CAE analysis of the muffler-pipe system is carried out to calculate the stresses due to oscillating loads. Figure 2 shows the Von-Mises stress contour near the transition due to two perpendicular bending moments. The average maximum Von-Mises stress due to this loading is around 449 MPa. A durability analysis is performed to predict the life and damage of the Muffler-pipe system. The S-N Curve is generated on basis of UTS in the Fatigue Process Manager. The Durability analysis is carried out with the load data from road load, mathematically transported the load signals to the centre of mass of the specimen, assuming My(t) and Mz(t) are significant factors in pipe entry fatigue. The FPM approach is followed to determine the damage and life of the components. The damage is found to be < 1 so the system will not fail to the applied loading condition. Figure 3. shows the Damage contour.


Figure 2:

Figure 3:

Hanger Design:

This CAE Simulation is designed to address fatigue sensitive Hanger design in the area of the Intermediate pipe when installed in a vehicle exhaust system .fatigue durability of hanger on Intermediate pipe. Hangerwelded to the bracket as shown in carries the whole system. The road load and engine vibrations are transferred thangers. A CAE analysis of the hFigure 4 shows the Von-Mises stress contour due to vertical loading. The average maximum Vonstress due to this loading is around 383damage of the hanger. The S-N Curve is generated on basis of UTS in the Fatigue Process Manager. The Durability analysis is carried out with the load data from road load as Fz determine the damage and life. loading condition. Minimum life of the component found to be 142200 cyclesand Damage contour.


Figure 2: Stress Contour Of Muffler-Pipe For Biaxial Loading

Figure 3: Damage Contour Of Muffler-Pipe For Biaxial Loading

This CAE Simulation is designed to address fatigue sensitive Hanger design in the area of the Intermediate pipe when installed in a vehicle exhaust system . This simulation is used to evaluate the vertical direction

Intermediate pipe. Hanger design in this case has a hwelded to the bracket as shown in Figure 4. The hanger is the critical part in the exhaust system as it carries the whole system. The road load and engine vibrations are transferred t

A CAE analysis of the hanger is carried out to calculate the stresses due to oscillating loads. Mises stress contour due to vertical loading. The average maximum Von

is around 383 MPa. A durability analysis is performed to predN Curve is generated on basis of UTS in the Fatigue Process Manager. The

Durability analysis is carried out with the load data from road load as Fz . The FPM approach is followed to determine the damage and life. The damage is found to be < 1 ,so the system will not fail to the applied loading condition. Minimum life of the component found to be 142200 cycles. Figure

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This CAE Simulation is designed to address fatigue sensitive Hanger design in the area of the Intermediate This simulation is used to evaluate the vertical direction

design in this case has a hanger rod which is hanger is the critical part in the exhaust system as it

carries the whole system. The road load and engine vibrations are transferred to the system through the anger is carried out to calculate the stresses due to oscillating loads.

Mises stress contour due to vertical loading. The average maximum Von-Mises A durability analysis is performed to predict the life and

N Curve is generated on basis of UTS in the Fatigue Process Manager. The The FPM approach is followed to

so the system will not fail to the applied Figure 5 & 6 shows the Life


Figure 4:

Figure 5:

Figure 6:


Figure 4: Stress Contour Of Hanger For Vertical Loading

Figure 5: Life Contour Of Hanger For Vertical Loading

Figure 6: Damage Contour Of Hanger For Vertical Loading

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Muffler Bracket Design:

This CAE Simulation is designed to address fatigue sensitive Muffler Bracketthe muffler when installed in a vehicle exhaust direction fatigue durability of Bracketcase has a hanger rod which is welded to the exhaust system as it carries the whole system through hanger rod. The road load and entransferred to the system through the calculate the stresses due to oscillating loads. Figure loading. The average maximum Vonanalysis is performed to predict the generated on basis of UTS in the Fatigue Process Manager. The Durability analysis load data from road load as Fzdamage is found to be < 1, so the system will not fail to the applied loading condition. Minimum life of the component found to be 2.5e19 cycles

Figure 7:

Figure 8:


This CAE Simulation is designed to address fatigue sensitive Muffler Bracket-Hanger design in the area of uffler when installed in a vehicle exhaust system. This simulation is used to evaluate the vertical

direction fatigue durability of Bracket- hanger on and adjacent to the muffler. Muffler banger rod which is welded to the bracket. The muffler bracket is the critical part in the

exhaust system as it carries the whole system through hanger rod. The road load and entransferred to the system through the hangers. A CAE analysis of the muffler bcalculate the stresses due to oscillating loads. Figure 7 shows the Von-Mises stress contour due to vertical

imum Von-Mises stress due to this loading is around 235analysis is performed to predict the life and damage of the muffler bracket design. The Sgenerated on basis of UTS in the Fatigue Process Manager. The Durability analysis load data from road load as Fz. The FPM approach is followed to determine the damage and life. The

the system will not fail to the applied loading condition. Minimum life of the to be 2.5e19 cycles. Figure 8 shows the Life contour.

Figure 7: Stress Contour Of Hanger Bracket For Vertical Loading

Figure 8: Life Contour Of Hanger Bracket For Vertical Loading

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Hanger design in the area of is used to evaluate the vertical

Muffler bracket design in this uffler bracket is the critical part in the

exhaust system as it carries the whole system through hanger rod. The road load and engine vibrations are hangers. A CAE analysis of the muffler bracket is carried out to

Mises stress contour due to vertical oading is around 235MPa. A durability

racket design. The S-N Curve is generated on basis of UTS in the Fatigue Process Manager. The Durability analysis is carried out with the

. The FPM approach is followed to determine the damage and life. The the system will not fail to the applied loading condition. Minimum life of the


Resonator - Pipe System:

This CAE Simulation is designed to address the forward end of a resonator when the ra vehicle exhaust system. This CAE Simulation is used to evaluate the bending fatiguforward pipe entry of resonator. whose diameter is slightly smaller than the pipes outside the muffler. Hence there is a transition zone in theresonator inside pipe. A CAE analysis of the rdue to oscillating loads. Figure perpendicular bending moments611MPa. A durability analysis is performed to predThe S-N Curve is generated on basis of UTS in the Fatigue Process carried out with the load data from road load of the specimen assuming My(t)and Mz(t ) are significant factors in pipe entry fatigue. Theis followed to determine the damage and life.applied loading condition. The damage found in the econtour. To confirm the result, region. The life estimated using FPM and life observed during testing are comparable with each other.

Figure

Figure


This CAE Simulation is designed to address fatigue sensitive design, in the area of exhaust pipe entry intothe forward end of a resonator when the resonator is mounted as the third component of a flex coupling in a vehicle exhaust system. This CAE Simulation is used to evaluate the bending fatiguforward pipe entry of resonator. The resonator-pipe system considered in this case, have internal pipe whose diameter is slightly smaller than the pipes outside the muffler. Hence there is a transition zone in the

A CAE analysis of the resonator-pipe system is carried out to calculate the stresses Figure 9 shows the Von-Mises stress contour near the transition due to two

bending moments. The average maximum Von-Mises stress due to this loading is around MPa. A durability analysis is performed to predict the life and damage of the r

N Curve is generated on basis of UTS in the Fatigue Process Manager. Theload data from road load mathematically transported load signals to the

of the specimen assuming My(t)and Mz(t ) are significant factors in pipe entry fatigue. Theis followed to determine the damage and life. The damage is found to be > 1, so the system will fail to the

ition. The damage found in the end cap fillet region. Figure physical biaxial test conducted and the system fails in the end cap fillet

The life estimated using FPM and life observed during testing are comparable with each other.

Figure 9: Stress Contour Of Resonator-Pipe For Biaxial Loading

Figure 10:Life Contour Of Resonator-Pipe For Biaxial Loading

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in the area of exhaust pipe entry into esonator is mounted as the third component of a flex coupling in

a vehicle exhaust system. This CAE Simulation is used to evaluate the bending fatigue durability of the considered in this case, have internal pipe

whose diameter is slightly smaller than the pipes outside the muffler. Hence there is a transition zone in the pipe system is carried out to calculate the stresses

Mises stress contour near the transition due to two e to this loading is around

ict the life and damage of the resonator -pipe system. Manager. The durability analysis is

ransported load signals to the centre of mass of the specimen assuming My(t)and Mz(t ) are significant factors in pipe entry fatigue. The FPM approach

so the system will fail to the nd cap fillet region. Figure 11 shows the damage

physical biaxial test conducted and the system fails in the end cap fillet The life estimated using FPM and life observed during testing are comparable with each other.


Figure 11:

Benefit Summary:

1. The FPM step by step approach of including input data is user friendly and helps in getting

2. Time taken for the durability analysis of the system

3. The FPM step by step approach for durability analysis reduces Product development time and Cost.

Conclusions:

Structural durability analysis of passenger car exhaustsexplained in this paper. The durability issues with the exhaust system components such as Mufflersystem, Hanger design, Muffler Bracket, Resonatorfailure has been considered for future

Altair HyperWorks FPM approach is very available load data. This methodology component design.

The authors would like to express their sincere thanks to our Manoj Vasanth Singh for their assistance to present this paper. We also thank the management of ShardaMotor Industries Limited for allowing us to present this work

[1] Jia Li , Shan Shih "Considerations in Conducting Structural Dynamic Analysis of Commercial Vehicle

Exhaust System" SAE Paper # 2006-

[2] Deming Wan , Christy Simms " Dynamic Analysis of a Full System Durability Test in Vehicle Exhaust

Systems" SAE Paper # 2001-01-1438.

[3] Reference guide of RADIOSS of Altair HyperWorks


11: Damage Contour Of Resonator-Pipe For Biaxial Loading

The FPM step by step approach of including input data is user friendly and helps in getting

Time taken for the durability analysis of the system by FPM approach is very less.

The FPM step by step approach for durability analysis reduces Product development time and Cost.

analysis of passenger car exhausts system components using FPM approach durability issues with the exhaust system components such as Muffler

system, Hanger design, Muffler Bracket, Resonator-pipe system are addressed and solution to avoid been considered for future work.

orks FPM approach is very effective tool to calculate life and damage of component using available load data. This methodology saves the product development time and cost

ACKNOWLEDGEMENTS:

The authors would like to express their sincere thanks to our colleagues Mr. Emerson, Mr.Sairaman, Mr.Manoj Vasanth Singh for their assistance to present this paper. We also thank the management of ShardaMotor Industries Limited for allowing us to present this work , done by us.

REFERENCES


-01-3573.

Dynamic Analysis of a Full System Durability Test in Vehicle Exhaust

1438.

of Altair HyperWorks

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The FPM step by step approach of including input data is user friendly and helps in getting better results.

by FPM approach is very less.

The FPM step by step approach for durability analysis reduces Product development time and Cost.

using FPM approach were durability issues with the exhaust system components such as Muffler-Pipe

addressed and solution to avoid

tool to calculate life and damage of component using product development time and cost with reliable

. Emerson, Mr.Sairaman, Mr. R. Manoj Vasanth Singh for their assistance to present this paper. We also thank the management of Sharda


Dynamic Analysis of a Full System Durability Test in Vehicle Exhaust

rl-03 structural durability analysis of passenger car exhaust … · 2017-10-27 · structural...

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