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CONSTRUCTION AND SIMULATEION Stress Analysis in Design with Plastics: Accessible Method with huge Impact

Von Dipl.-Ing. Marian Bulla Director - Program Management, Altair Engineering, Nasdaq, Cologne und Dr.-Ing. Vladimir A. Kolupaev Research associate at Fraunhofer LBF, Mechanics & Simulation, Darmstadt 1 min Lesedauer

Multiaxial stress states in components are evaluated with the methods of stress analysis. However, when designing with von Miseshypothesis, under dimensioning can occur for multiaxial tensile loadings. More complex strength criteria require further tests for parame ter fitting. However, these tests are of ten costly and may be subject to excessive scatter. As an alternative, the parameters can be estimated on the basis of model based assumptions. 

Hypotheses for “ideally ductile” material behavior (von Mises, Tresca, and Schmidt-Ishlinsky) and the normal stress hypothesis (NSH) for “absolutely brittle” material behavior in the normalized diagram 𝜎𝜎I−𝜎𝜎II, 𝜎𝜎III=0 [7], cf. [17].(Bild:)
Hypotheses for “ideally ductile” material behavior (von Mises, Tresca, and Schmidt-Ishlinsky) and the normal stress hypothesis (NSH) for “absolutely brittle” material behavior in the normalized diagram 𝜎𝜎I−𝜎𝜎II, 𝜎𝜎III=0 [7], cf. [17].
(Bild:)

Established procedures for design of thermoplastic components under static loading are primarily based on the strength criteria developed for metallic materials, which are implemented in every commercial FEM software. These criteria are usually simple and can be fitted with the data from the uniaxial tensile test only.