Ductile damage in Taylor-anvil and rod-on-rod impact experiment

J. dynamic behavior mater.

Ruggiero

et al. 2015

The dynamic tensile extrusion (DTE) test offers unique possibility to probe material response under very large plastic strain, high strain rate and temperature to support constitutive modelling development. From the computational point of view, the DTE test is particularly challenging and a number of issues need to be assessed before proceeding with material modelling verification. In this work, an extensive and detailed computational work was carried out in order to provide the guidelines for accurate simulation of DTE test. Two constitutive models, the first phenomenological the latter physically-based, were used to simulated the behavior of fully annealed OFHC copper in dynamic extrusion at different velocities. Material models parameters were calibrated using uniaxial test data at different strain rates and temperatures. The number, size and shape of the ejected fragments at different velocity were used as validation metrics for the selected constitutive models. Results indicate that material behavior under dynamic extrusion can be accurately predicted limiting the influence of numerical parameters not related to the constitutive model under investigation. The physically based modelling allows a more accurate prediction of the material response and the possibility to incorporate microstructure evolution processes, such as dynamic recrystallization, which seems to control the response of OFHC copper in DTE tests at higher velocity.

Section: Introductionmentioning

confidence: 97%

Numerical Simulation of Dynamic Tensile Extrusion Test of OFHC Copper

J. dynamic behavior mater.

Ruggiero

et al. 2015

“…At failure, for D=D cr , assuming that the strain threshold for damage initiation is pressure independent -which is reasonable at relatively low stress triaxiality while it is not true in general [16,24,25] -the following expression can be obtained,…”

Section: Damage Modelmentioning

confidence: 99%

Strain capacity assessment of API X65 steel using damage mechanics

Frattura Ed Integrità Strutturale

Gentile

et al. 2017

International audienceStrain-based design for offshore pipeline requires a considerable experimental work aimed to determine the material fracture toughness and the effective strain capacity of pipe and welds. Continuum damage mechanics can be used to limit the experimental effort and to perform most of the assessment analysis and evaluation in a simulation environment. In this work, the possibility to predict accurately fracture resistance of X65 steel using a CDM model proposed by the authors, is shown. The procedure for material and damage model parameters identification is presented. Damage model predictive capability was demonstrated predicting ductile crack growth in SENB and SENT fracture specimens

“…In the last decades, the Bonora damage model (BDM) was validated extensively for different materials and practical engineering cases. Iannitti et al [14,15] used the BDM to explain while ductile damage cannot occur in Taylor impact cylinder test of highly ductile metals (OFHC ad AL 1100-O) while, because of the different stress triaxiality state, it does occur in symmetric Taylor impact test (rod-on-rod) under equivalent velocity conditions. The BDM was also used to predict ductile tearing initiation and propagation in structural components such as deep water offshore pipeline welds [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Modification of the Bonora Damage Model for shear failure

Frattura Ed Integrità Strutturale

Ruggiero

et al. 2018

The Bonora damage model was extended to account for shearcontrolled damage. To this purpose, a new definition for the damage dissipation potential in which an explicit dependence on the third invariant of deviatoric stress was proposed. This expression leads to damage rate equation in which two contributions, the first for void nucleation and growth damage process the latter for shear fracture, can be recognized. For the J III controlled damage contribution, only two additional material parameters are necessary of easy experimental identification The extended model formulation was verified predicting the failure locus for AL 2024-T351 alloy. Finally, the failure locus for stress state combinations, where the minimum material ductility is expected, was determined.