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Pawan SinghManager, CAE
Javed QuershiJunior Manager, CAE
Rohit LilhareJunior Manager, CAE
Vibration Analysis of Tractor fender Assembly and T est Correlation Using Optistruct
Eicher Tractors, Mandideep
Date: 13/06/2014
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Company Profile
TAFE Motors and Tractors Limited ( TMTL ) is a who lly owned subsidiary of
TAFE, set up in 2006 when TAFE acquired Eicher trac tors. The Eicher brand of
tractors has a distinguished heritage of 50 years i n India. Known for its unique
distinction of offering a range of both air and wat er cooled tractors, its tractors
span the 24 to 60 HP range and have been well recei ved in the segment. Eicher’s
less than 30 HP range has commanded market pre-emin ence in the segment.
TAFE today is recognized as a high quality mass man ufacturer with a extensive
product range to meet every farming need.
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Vibration Analysis of Tractor fender Assembly and T est Correlation
Objective of case study:-
Tractor fenders are prone to failures because It i s subjected to heavy dynamic
loads during various field Operation with implement such as Ploughing, Puddling,
Haulage etc. as well as in static condition (at idl e RPM). To evaluate the structural
performance of tractor fender, it is necessary to determine "g ‟ levels of
acceleration at fender mounting location. Also, onc e the test data is available, it
can be used for correlating it with the FEA results and then load history can be
used for reliable analysis to develop the product. The methodology helps in
moving towards virtual testing and to avoid/reduce physical testing of the sub-
systems to adhere to the constraints on time and co st.
Statement of problem:-
� 1. To carryout Static and dynamic analysis of Fende r for structural strength
� 2. To correlate the test results ( shaker ) with FE A results.
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ACTUAL FIELD USAGES ANF RIG SIMULATION
Rough Road
Puddling
Haulage
Shaker
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Methodology
Experimental test measurements with Various application
FEM Modal Analysis
Modal Superposition
Frequency Response Analysis
Test Correlation
Design IterationFinal Design Validation
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The fender assembly components such as stiffener , brackets, canopy are made
of Structural steel of various grades. FE model has been developed by using pre-
processing software HyperMesh. Metal parts are mode lled with shell elements
CQUAD and CTRIA by extracting mid surfaces . Bolted connections between two
components are modelled with CBEAM elements. The we ld between each
component is modelled with shell elements of averag e of thickness. The masses
of individual parts and whole assembly were careful ly cross checked for good
accuracy of frequency results.
FE Modeling
Fender Assembly
Fender
Back-rest
Stiffner
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Loadcases
Static Analysis 1. Vertical downward direction : Weight of 3 or 4 people 2. Braking load at back rest & Mudguard3. Cornering load at back rest & Mudguard 4. Mudguard with Canopy
Dynamic analysis 1.Modal analysis – Natural Frequencies 2.Frequency Response Analysis to find effect of engine
vibration
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Frequency Response Analysis
This particular analysis was carried out to predict and reduce the road
induced vibration. The fender assembly where it is mounted was
considered for simulation. These boundary condition s were used for
both Modal as well as Frequency response analysis H ere acceleration
derived from road load data is used to excite the a ssembly over an
operational frequency range as dynamic load. Stress and displacement
peaks are determined for the considered frequency r ange. This method
can be used to simulate and predict the actual resp onse.
Frequencies below 10 Hz are not usually considered. The reason is that,
lowest idling rpm is usually above 600 rpm.
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Field Failure Simulation
Stress =144 Mpa
Actual field failure
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Test Correlation
The simulation results are also well correlated by the experimental results in which failure location and pattern is ex actly matched. Further modifications have been incorporated in design to m eet the strength requirement .
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Design Improvements
Different design iterations were analyzed as per the methodology, so as
to shift the natural frequency.
The 1st design proposal, weld location to be changed and i ncreased to
50 mm from 30mm. It has natural frequency of 22 Hz, which results
same vibration levels as base design in frequency r esponse analysis.
In case of 2 nd design proposal, vertical Stiffener height to be in creased
and welding location to be changed than the base de sign resulting in
significant reduction in vibration levels using fre quency response
analysis.
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Analysis and Test Methodology
Initially modal analysis was carried out to estimat e the natural
frequencies of the system. First 10 modes were extr acted in this
analysis.
Acceleration were measured at different locations . Sensor locations on
were chosen such that maximum sensitivity was obser ved.
The measured acceleration Peak value on the fender at base locations
were in turn used for the Frequency Response analys is in Optistruct.
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Loads and Boundary Conditions
Constrained in all directionTest Rig Set up
FE Modeling as Per testing shaker setup
•Measured Acceleration data used for Resonance test at shaker table, Which simulate the same field failure Zone.
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Design Improvements
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Experimental Test Set-up
The fender assembly is tested on shaker table test rig by mounting on
fixture at the bottom plate , with acceleration val ue generated from road
load data, over the operational frequency range.
Tri Axial accelerometer
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Benefits summary
Using FEA based Eigen frequency and frequency respo nse analysis
techniques, the vibration characteristic of fender can be faithfully
replicated as observed in the physical test.
Multiple design proposals could be evaluated in vir tual environment to
arrive at best and optimum design solution. The bes t design proposal
showed reduction in vibration level by 55.2%. Physical test on final
design reconfirmed simulation results and satisfact ory performance of
the final design.
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Conclusion
Optistruct has been used to model and simulate the b ehavior of the
Fender Assembly for Vibrations. The results are mat ching closely with
the experimental test and required design modificat ions have been done
from analysis and iterations.
The work presented in this paper is in the early ph ases of ongoing work
and it is important to note these promising results will strongly demand
more detailed analysis for future projects.
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Acknowledgements/Credits
The authors would like to acknowledge our Design, P rototype and
testing teams for extending their kind support. The authors would also
like to thank the R&D Chief Mr. Hemant Shrikhande , and Testing Head
Mr. Suresh Gopal , Divisional Manager Design Mr. R. S. Kaushik Eicher
tractors for providing this opportunity for publish ing the work.