The Lambda Factor

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w w w . a u t o s t e e l . o r g Joint Analysis - Conclusions • The response of a structure to changes in wall thickness can be used to predict the weight savings from material substitution • λ is a very good predictor of weight savings for equivalent stiffness • Average λ = 1.51 – Average weight savings of 30% in joints for steel to aluminum material substitution • Variations in geometry between joints cause the changes in λ for the different joints • λ for a joint can be changed through redesign and reinforcement
• Gauge sensitivity can be assessed for individual components, cross sections, or full vehicle body structures. • The parameter is very well suited for evaluating the weight changes associated with material, architecture, and/or gauge changes. • For the negligible-web beam, l ranges between 1.0 (uniform internal load distributions, very efficient structure) to 3.0. (non-uniform internal load distribution, less efficient structure). • Other effects that have effect of increasing λ include torsional loads, shear lag, elastic instability associated with compressive buckling. • For structures with low λ values, the mass savings generated by a constant-stiffness material substitution is proportional to the ratio of specific elastic moduli: Δ m ⎡ E1 / ρ = 100⎢1− ⎣ E2 / ρ 1 2 ⎤ ⎥ ⎦ Generalization of the Theory w w w . a u t o s t e e l . o r g
Page 1 and 2: The Lambda Factor By Paul Geck, Ric
Page 3 and 4: • Concept • Geometric Effects
Page 5 and 6: • Flat plate has bending stiffnes
Page 7 and 8: Beam Geometric Non-linearities •
Page 9 and 10: w w w . a u t o s t e e l . o r g B
Page 11 and 12: Summary of λ and Beam Geometric Ef
Page 13 and 14: 1mm thickness λ = 1.3 6.25mm thick
Page 15 and 16: • Equations: • θ = (δ 1 - δ
Page 17 and 18: w w w . a u t o s t e e l . o r g C
Page 19: Inboard-outboard loading Original M

The Lambda Factor

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