Ein stochastisches, schadensmechanisches Versagensmodell für Komposite

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A pointwise probability density for failure initiation is proposed regarding the evaluation of damaged composite structures. The local cumulative damage measure accounts for both the accumulation of local stochastic microdamaging and the load redistribution to undestroyed subregions. It bases on the global failure rate of heterogeneous composites. Firstly the damage behaviour of beams under load is studied. Secondly it is proved that stress redistribution by a crack tip damage zone yields to the disappearence of singularity dominated stress fields.

Section: Numerische Simulationunclassified

Lokales kumuliertes Schadensmaß für Komposite ‐ Rißspitzen ohne Singularität

Will

Helbig

1997

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“…[l, 21) oder ganz allgemein von Materialveranderungen im Werkstoff begleitet. Sie fuhren zu einem nichtlinearen Spannungs-Dehnungsverhalten derartiger Materialien [ 3 ] . Das Gebiet der nichtlokalen Schadigungen wird im folgenden unter dem Begriff Schadigungszone gefuhrt .…”

Section: Introductionunclassified

R‐Kurven von energiedissipativen Werkstoffen mit Schädigungszone. Teil 1: Energieumsatz am Riß

Will¹

1993

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Der vorliegende Artikel beschaftigt sich damit, wie die Energiebilanz am Ria formuliert werden mul3, wenn nichtlokale energiedissipative Schadigungen das RiRwachstum begleiten. Die lokale Energiebilanz wird verwendet , urn die Relationen zwischen den verschiedenen Energieanteilen zu klaren, die sowohl im ProzeB der Materialtrennung als auch f i r nichtlokale Schadigungen in der Umgebung der RiRfront verbraucht werden. Der 1. Hauptsatz der Thermodynamik ermoglicht die Identifikation und Definition geeigneter Bruchkennwerte. Die Ergebnisse werden rnit Ideen von Turner verglichen, welcher den RiBwiderstand im Beisein groRer plastischer Zonen mit der Energiedissipationsrate verkniipft. R-Curves of Energy Dissipative Materials Part 1: Energy Consumption at the CrackThe paper deals with the way in which the energy balance should be formulated when nonlocal damage processes associated with energy dissipation accompany crack growth. The local energy balance is used to rearrange the relationships between the different energies consumed both in the process of material separation and due to nonlocal damaging around the crack tip. The first law of thermodynamics allows the identification or definition of appropriate crack driving forces. The results are compared with recent ideas of Turner on defining tearing resistance for uncontained yield through energy dissipation rate.

Application of continuum damage mechanics model in terms of fatigue life assessment for low cycle and quasi static loadings

Skibicki

Ligaj

2018

The aim of this study is to test the classical Lemaitre model based on continuum damage mechanics (CDM) approach in the range of low cycle and quasi‐static fatigue life. Study is carried out with the use of results of experimental tests for C45 steel (according to AISI: 1045 steel) carried out under variable‐amplitude loading. Loading programs are of two‐step character and include blocks of cycles of different lengths and R = ‐1 coefficients. Fatigue lives are calculated according to Lemaitre model from experimentally obtained stress and strain histories recorded during fatigue tests. The results are compared with experimental tests results and with fatigue lives calculated with the use of by traditional fatigue approach based on Palmgren‐Miner damage summation hypothesis. Experimental test of fatigue life calculation results for C45 steel reveals that continuum damage method, using the recorded stresses and strains, predicts fatigue life better as compared to the remaining methods. The study also contains many detailed analyses of experimental results.