Post on 27-Nov-2021
Topology optimization of automotive components subjected to low cycle fatigue
Frankenthal, 28.06.2017András TANOS, R&D Engineer
FÉMALK Co. – at a glance
Usual requirements of engine suspension mounts
Material testing
• Monotonic properties• Cyclic properties
Validation of material models
Optimization with fatigue constraint
CAD interpretation
Verification
Questions
Contents
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Introduction - FÉMALK Co.
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Aluminium high pressuredie casting foundry
Founded in 1989
100 % family ownership
100 % automotive industry
€ 93,3 million income in 2016
250 - 1000 ton machines
More than 1100 coworkers
Major customers - FÉMALK Co.
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Development project - Requirements
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Dimensions
Feasibility
Prescribed minimum breaking force
Low-cycle fatigue requirementss of fully reversed load cycles
Maximum mass
Prescribed minimum of the first natural frequency
Monotonic material properties
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𝑅𝑅𝑅𝑅𝑅.2 - 0.2% Offset yield strength𝑅𝑅𝑚𝑚 - Ultimate tensile strength𝐸𝐸 - Modulus of elasticity (Young’s modulus)𝐾𝐾 - Monotonic strength coefficient𝑛𝑛 - Monotonic strain hardening exponent
𝜀𝜀 = 𝜀𝜀𝑒𝑒 + 𝜀𝜀𝑝𝑝 =𝜎𝜎𝐸𝐸 +
𝜎𝜎𝐾𝐾
1𝑛𝑛
Cyclic measurements
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𝐾𝐾𝐾 - Cyclic strength coefficient𝑛𝑛𝐾 - Cyclic strain hardening exponent
𝜀𝜀 = 𝜀𝜀𝑒𝑒 + 𝜀𝜀𝑝𝑝 =𝜎𝜎𝐸𝐸 +
𝜎𝜎𝐾𝐾𝐾
1𝑛𝑛′
Cyclic measurements
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𝜀𝜀𝑎𝑎 = 𝜀𝜀𝑎𝑎𝑒𝑒 + 𝜀𝜀𝑎𝑎𝑝𝑝 =
𝜎𝜎𝑓𝑓𝐾𝐸𝐸 2𝑁𝑁𝑓𝑓
𝑏𝑏 + 𝜀𝜀𝑓𝑓𝐾 2𝑁𝑁𝑓𝑓𝑐𝑐
𝜎𝜎𝑓𝑓𝐾 - Fatigue strength coefficient𝑏𝑏 - Fatigue strength exponent𝜀𝜀𝑓𝑓𝐾 - Fatigue ductility coefficient𝑐𝑐 - Fatigue ductility exponent
Validation, FEM
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Validation
9/14
𝐹𝐹, kN Life, -
9 4509 4409 370
Development of a new component
10/14
Interpretation, CAD
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Verification of final design
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feasibility static strength Fatigue life mass 1st natural frequency
original proposal not OK questionable unknown 2111 g 755 Hz
final geometry OK OK OK 1755 g 866 Hz
Ansys results Optistruct results
Similar, optimized project
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Mass: -400 gRigidity: ↑Strength : ↑Feasibility : OK
1650 g1250 g
Predecessorgeometry
STL from OSSmooth
Optimized design
References
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Y.-L. Lee, J. Pan, R. Hathaway and M. Barkey, Fatigue Testing and Analysis, Burlington: Elsevier Butterworth-Heinemann, 2005.
ASTM, “Standard practice for statistical analysis of linear or linearized stress-life (S-N) and strain-life (e-N) fatigue data,” ASTM Standard E 739, Vols. ASTM Designation E 739-91, pp. 1-7, 1998.
Altair, “OptiStruct optimization training material,” Cologne, 2016.
ASTM, “Standard practice for strain-controlled fatigue testing,” ASTM Standard E 606, Vols. ASTM Designation: E 606-92, pp. 1-7, 1998.
C. R. Williams, Y.-L. Lee and J. Rilly, “A practical method for statistical analysis of strain–life fatigue data,” International Journal of Fatigue, vol. 25, no. 5, pp. 427-436, 2003.
M. Avalle, G. Belingardi, M. P. Cavatorta and R. Doglione, "Casting defects and fatigue strength of a die cast aluminium alloy: a comparison between standard specimens and production components," International Journal of Fatigue, vol. 24, pp. 1-9, 2002.
B. Desmorat and R. Desmorat, “Topology optimization in damage governed low cycle fatigue,” Comptes Rendus Mécanique, vol. 336, pp. 448-453, 2008.
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Thank you for your attention!