NOISE REDUCTION ON AGRICULTURAL TRACTOR BY SHEET METAL OPTIMIZATION TAFE LIMITED

Transcription

1 NOISE REDUCTION ON AGRICULTURAL TRACTOR BY SHEET METAL OPTIMIZATION TAFE LIMITED SK MD ASIF BASHA (SENIOR MEMBER COE NVH) M SUNDARAVADIVEL (SENIOR MEMBER NVH) Date (22 nd July 2016)

2 Tractors and Farm Equipment Limited Tractors and Farm Equipment Limited (TAFE), is a unit company of the Amalgamations Group Consists of 43 Companies, 37 Manufacturing Plants and a work-force of a little over 15, 000. Has grown under the leadership of Shri.A.Sivasailam, its Chairman, Ms Mallika Srinivasan, Chairman & CEO of TAFE was conferred with Padma Shri in TAFE STRENGTH IN INDIA Strong Domestic presence Second largest in the country Reputed for quality products and after sales support Low cost of ownership & Highest resale value Consistently pursuing excellence

3 NOISE REDUCTION ON AGRICULTURAL TRACTOR BY SHEET METAL OPTIMIZATION Objective of case study The Objective of this study is noise and vibration reduction on an agricultural tractor by optimizing sheet metal components. To Perform Simulation for Complete Fender and Platform Assembly and correlation of the same with the Test results. Statement of problem This paper outlines the systematic approach for Sheet Metal Optimization through CAE simulations. The baseline FE model is developed with standard FE modelling methods and correlated with the test results. FE modeling techniques were reviewed and optimized based on development tests and the structural modifications were carried on the Complete Fender and Platform Assembly. here 3

4 Sources of Noise & Vibration in Tractor Exhaust Noise Transmission Noise Gear Rattle & Whine Structure Borne Noise Sheet Metal Components Housings, etc. here 4

5 Process Methodology Baseline CAE evaluation of the Fender Assembly Baseline Testing and Measurements on Tractor Physical test and Simulation correlation Improvements in FE model based on test correlation CAE based design modification iterations Certification test and correlation here 5

6 Noise db(a) Baseline Testing and Measurements Driver ear noise measurement Using microphones Vibration measurement on fender using accelerometer Vibration measurement on platform using accelerometer here 6

7 FE Model and Loading Foot rest Fender Assembly here 7 Mounting Bracket Reinforcements FE Model Major structural parts considered for FE model Cad data is converted to FEA model. Mesh type is taken as Mixed (quad & tria) elements and mesh Size is Considered as 3~ 5mm. All are connected with Rigid Elements (Seam Welds, Spot Welds and Bolts). Constant damping assumed based on previous experience. Load & BC ~25 load collectors (Eigrl, Spc,Tabled,Spcd,Freq1,Rload, Tabdamp1,etc..) are used to carry out vibration response analysis. Acceleration is given as input in the Mounting location of Fender and Platform. Frequency range Considered is from Hz.

8 Frequency (Hz) Frequency (Hz) Baseline Simulation Modal Analysis Fender Modes Mode 1 Mode 2 Mode 7 Physical Test and Simulation Correlation Platform Modes Fender Modes Mode Number here 8 Mode Number

9 Vibration Correlation Fender- Vibration Response Constrained and Acceleration is applied at mounting locations. TEST DATA Fender Back here 9 Correlating Test and CAE Data. The Peak coming at 49 Hz is in Vertical Direction in Test Data. The Peak coming at 48 Hz is in Vertical Direction in CAE Data.

10 Vibration Correlation Platform - Vibration Response TEST DATA Platform Rear here 10 Correlating Test and CAE Data. The Peak coming at 180 Hz is in Vertical Direction in Test Data. The Peak coming at 182 Hz is in Vertical Direction in CAE Data.

11 here 11

12 CAE Based Final Design Structural Modifications Fender Platform Many iterations (>~30) have been performed in an effort to reduce Fender & Platform vibration. Final Iteration Structural Modifications are shown in the above Figures. Top Reinforcement, Side Reinforcement are the Major Modifications in the Fender. Bottom Reinforcements are added on both sides in Platform. Simulation helps to reduce development time and cost. here 12

13 Vibration Vibration Correlation Simulation- Base vs Improved y-axis Platform Rear z-axis Fender Front Reduction in vibration compare to baseline is observed. Improved model is giving 40-45% reduction compared to base model. here 13

14 Vibration Vibration Proposal / Optimization for Improvement Vibration comparison on fender Vibration comparison on platform here 14

15 Noise db(a) Prototype Testing Base Vs Improved DPNL (Base vs Improved) Measurement location LHS Fender Top front - X axis LHS Fender Top rear - X axis LHS Platform front - Z axis LHS Platform rear - Z axis RHS Fender Top front - X axis RHS Fender Top rear - X axis RHS Platform front - Z axis Test condition Baseline With improvement Changes happened Peak vibration Peak vibration Overall Overall Operating Operating vibration Vibration Operating vibration Vibration Overall speed Frequency speed Frequency level level condition level level value (rpm) (Hz) (rpm) (Hz) (m/s2) (m/s2) (m/s2) (m/s2) m/s2 Operating condition Vibration level change Percentage Percentage Peak change in change in value overall peak m/s2 (%) (%) Idling speed Idling speed Max torque Max torque Flyup speed Flyup speed Peak value Peak value Idling speed Idling speed Max torque Max torque Flyup speed Flyup speed Peak value Peak value Idling speed Idling speed Max torque Max torque Flyup speed Flyup speed Peak value Peak value Idling speed Idling speed Max torque Max torque Flyup speed Flyup speed Peak value Peak value Idling speed Idling speed Max torque Max torque Flyup speed Flyup speed Peak value Peak value Idling speed Idling speed Max torque Max torque Flyup speed Flyup speed Peak value Peak value Idling speed Idling speed Max torque Max torque Flyup speed Flyup speed Peak value Peak value Total 38 % 61 % Vibration (Base vs Improved) LHS 33 % 60 % RHS 43 % 61 % Significant reduction (about 0.5 db(a)) is observed in the driver ear noise level. The improved sheet panels shows about 38% reduction in the vibration level. here 15

16 Benefits Summary 1. Vibration at fender and platform of tractor is predicted with good correlation. 2. Correlated model was used for design optimization to reduce vibration. 3. Approximately 30 design concepts were simulated and studied. 4. Nearly 3 Months of time and proto costs were saved by avoiding physical testing. here 16

17 Conclusion A good correlation in terms of vibration was observed in physical test and simulation for baseline model. The correlated FE model was used for structural optimization using simulation and was implemented in final design. Prototype based upon final selected design was tested and vibration levels were measured. The results show vibration reduction by 38%. The above study and the process developed will help in refining FE modelling techniques and to reduce number of physical tests in future. The major structural resonances can be identified and will be addressed through structural optimization for vibration reduction at early design stage. here 17

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