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1

Investigating the capability of the Lemaitre damage model to establish the incremental sheet forming process

Kumar Pavan, Tandon Puneet

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e66, 1--18

EN

This paper presents the numerical and experimental investigation of the incremental sheet forming (ISF) process with the Lemaitre damage model to incrementally form parts of conical shapes. The Lemaitre damage model was prepared as a material subroutine (VUMAT) and linked to Abaqus/Explicit. The elastic–plastic parameters for the simulation were identified through tensile testing of the ASTM E8 specimen. The digital image correlation (DIC) was performed during the tensile testing to identify the damage parameters of the Lemaitre damage model. Scanning electron microscopy (SEM)-based area method was used to identify the area fraction vis-a-vis the variation of the strain. Thereafter, the identified area fractions with respect to strains have been calibrated to obtain the damage parameters through an inverse analysis approach. The identified parameters were used to form conical objects of Al1050 H14 sheets of 2 mm thickness through finite element (FE) simulation. The results obtained through FE simulation were compared with the experimental outcomes to investigate the efficiency of the Lemaitre damage model to simulate the ISF process. The responses obtained through FE simulation and experiments have been discussed in terms of limiting wall angle and forming depth, damage evolution, deformation mechanism, forming limit diagram, geometrical accuracy, forming forces, thickness distribution, and surface roughness.

2

Crack damage evolution in concrete coarse aggregates under microwave‑induced thermal stress

Yuan Yuan, Shao Zhushan, Qiao Rujia, Guo Xuan, Wang Weitao

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 3

art. no. e108

EN

Coarse aggregates of waste concrete can be efficiently separated from mortar under microwave irradiation. However, the microwave-induced damage in aggregates are restricting mechanical properties of the aggregates for replacing natural aggregates. Since damage evolution in rocks treated by microwave are influenced by mineralogy and microwave operating parameters, such as power and irradiation time, understanding the microwave weakening mechanism of rocks is necessary to assess and control the damage of aggregates for recovery of high-quality concrete coarse aggregates. This article develops an approach for evaluating crack damage evolution in aggregates exposed to microwave by combining theoretical analysis with experimental investigation. A theoretical heat source-matrix model based on electromagnetic and thermal properties of mineral components is established for microwave heated aggregates. Substituting microwave irradiating parameters and mineralogy of the aggregates into the model, corresponding temperature fields and thermal stress fields are solved. Cracks in aggregates after microwave exposure are observed using scanning electron microscopy (SEM) and quantified in terms of crack length, density and intensity. Crack damage varied with microwave energy is assessed by crack length and density. Crack propagation is further discussed by contrast of stress intensity factor (SIF) at the crack tip and fracture toughness of the aggregate. Cracking behavior analyzed by SIF of cracks is consistent with that obtained from quantitative analysis on SEM images. The results suggest that granite shows a stronger resistance to thermal stress damage compared with basalt under microwave exposure, and a multistage microwave treatment should be adopted for recovery of various aggregates.

3

A physically based constitutive model of Ti-6Al-4 V and application in the SPF/DB process for a pyramid lattice sandwich panel

Wu Yong, Wu Dipeng, Ma Jia, Xiao Wenchao, Zheng Kailun, Chen Minghe

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

366--382

EN

The physically based constitutive modeling, simulation and experimental of a superplastic forming and diffusion bonding (SPF/DB) process were studied for the manufacture of a pyramid lattice Ti-6Al-4 V sandwich panel structure. The high-temperature deformation behaviors of Ti-6Al-4 V were studied using uniaxial tensile tests at various temperatures 860 – 950 °C and strain rates 0.0001 s−1 ~ 0.01 s−1, corresponding microstructures were observed using optical microscope (OM) and Electron Backscattered Diffraction (EBSD). Based on obtained flow behavior and microstructure, a set of physically based constitutive equations of the Ti-6Al-4 V was established and used to simulate the superplastic forming for a pyramid lattice sandwich panel. The thinning ratios, dislocation densities, grain sizes and damage distributions of the sandwich panels were successfully predicted by the finite element (FE) simulation. A pyramid lattice Ti-6Al-4 V alloy sandwich panel with good dimensional accuracy and mechanical properties was manufactured by the SPF/DB process at 920 °C with a gas loading path of 0.0005 MPa/s. The maximum thickness thinning ratio, damage factor and relative grain size at the ribs of the sandwich panel were 26.3%, 6.7% and 0.94, respectively. The established constitutive model aids the FE simulations of SPF/DB manufacture of sandwich panels’ structure enabling both macro- and micro-properties to be synergistically controlled and guides the practical process optimizations.

4

Application of an interface damage model to steel reinforced concrete: a study of the size effect

Vodička R., Krajníková K., Baranová L.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2018

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z. 65, nr 4

103--112

EN

Influence of the size of steel reinforcement of a concrete structure on crack initiation at the interface between the steel fibre and the concrete body of the structure is under consideration. Numerical analysis is provided using a quasistatic delamination model for interface rupture based on an energetic approach using a cohesive zone model for providing the interface stress-strain relation. The obtained results confirm expected dependence of the critical load which causes triggering of the interface crack on a structure dimension parameter.

5

Experimental analysis and modelling of fatigue crack initiation mechanisms

Ustrzycka A., Mróz Z., Kowalewski Z. L.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 4

1443--1448

EN

The present work is devoted to simulation of fatigue crack initiation for cyclic loading within the nominal elastic regime. It is assumed that damage growth occurs due to action of mean stress and its fluctuations induced by crystalline grain inhomogeneity and the free boundary effect. The macrocrack initiation corresponds to a critical value of accumulated damage. The modelling of damage growth is supported by Electronic Speckle Pattern Interferometry (ESPI) apparatus using coherent laser light.

6

Analiza odkształcenia i powstawania pęknięć w procesie kucia stali austenitycznej

Kukuryk M.

Hutnik, Wiadomości Hutnicze

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2016

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Vol. 83, nr 2

67--71

PL

W pracy przedstawiono wyniki termomechanicznej symulacji procesu kucia wydłużającego stali austenitycznej X6CrNiTi18-10 w kowadłach płaskich i kształtowych z zastosowaniem metody elementów skończonych. W badaniach zastosowano nowy sposób kucia, polegający na wprowadzeniu wstępnego przekucia materiału wyjściowego w kowadłach o wypukłych powierzchniach roboczych i zasadniczego kucia w kowadłach kształtowych. Rezultaty obliczeń umożliwiają określenie rozkładu intensywności odkształcenia, intensywności naprężeń, naprężeń średnich i temperatury w objętości odkuwki. Wyniki badań uzupełniono o prognozowanie powstawania pęknięć ciągliwych podczas kucia. Porównanie teoretycznych i eksperymentalnych rezultatów badań wskazuje na dobrą ich zgodność.

EN

The paper presents the results of the thermal-mechanical simulation for the cogging process of the X6CrNiTi18-10 austenitic steel on flat and shaped anvils with the application of the finite element method. In the research, a new method of forging, consisting in the introduction of the initial reforging of the stock on anvils which have convex work surfaces, and further forging on shaped anvils, was applied. The results of the calculations make it possible to determine effective strain distribution, effective stress, mean stresses and temperature in the volume of a forging. The results of the studies have been complemented with the prediction of the occurrence of ductile fractures during forging. Good agreement between theoretical and experimental results was observed.

7

Constitutive modelling of damage evolution and martensitic transformation in 316L stainless steel

Ryś M.

Acta Mechanica et Automatica

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2016

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Vol. 10, no. 2

125--132

EN

In this work, the constitutive model, derived with the use of thermodynamic of irreversible processes framework is presented. The model is derived under the assumption of small strains. Plastic strain induced martensitic phase transformation is considered in the austenitic matrix where the volume fraction of the martensite is reflected by a scalar parameter. The austenitic matrix is assumed as the elastic-plastic material and martensitic phase is assumed as randomly distributed and randomly oriented inclusions. Both phases are affected by damage evolution but there is no distinction in the model between damage in austenite and martensite.

8

Modeling of damage evolution and martensitic transformation in austenitic steel at cryogenic temperature

Ryś M.

Archive of Mechanical Engineering

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2015

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Vol. LXII, nr 4

523--537

EN

In the present work, a constitutive model of materials undergoing the plastic strain induced phase transformation and damage evolution has been developed. The model is based on the linearized transformation kinetics. Moreover, isotropic damage evolution is considered. The constitutive model has been implemented in the finite element software Abaqus/Explicit by means of the external user subroutine VUMAT. A uniaxial tension test was simulated in Abaqus/Explicit to compare experimental and numerical results. Expansion bellows was also modelled and computed as a real structural element, commonly used at cryogenic conditions.

PL

W artykule przedstawiono konstytutywny model materiału podlegającemu przemianie fazowej wywołanej odkształceniami plastycznymi oraz rozwojowi uszkodzeń. Przemiana fazowa opisana jest modelem liniowym. Ponadto, w pracy uwzględniono izotropowy rozwój uszkodzeń. Opis konstytutywny został zaimplementowany w komercyjnym programie Abaqus/Explicit z wykorzystaniem zewnętrznej procedury użytkownika VUMAT. Dokonano symulacji testu jednoosiowego rozciągania w celu porównania wyników eksperymentalnych z numerycznymi. Jako przykład rzeczywistego elementu konstrukcyjnego, pracującego w warunkach temperatur kriogenicznych, dokonano symulacji pracy kompensatora.

9

Adaptive multiscale analyses on structural failure considering localized damage evolution on vulnerable joints

Zheng Z. Y., Li Z. X., Chen Z. W.

Archives of Civil and Mechanical Engineering

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2014

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Vol. 14, no. 2

304--316

EN

Deterioration in structures starts from meso-scale defects on vulnerable joints where damage evolution becomes main reason of fatigue accumulation. Therefore analyses on structural failure induced by fatigue accumulation must be carried out in multi-scale. This paper is aimed to provide a multi-scale computational approach for structural failure analyses. Scale coupling method based on numerical integrated constraint equations is developed. This scale coupling method can guarantee sufficient computing precision when material at the trans-scale boundary keep elastic. However in structural deterioration process, material nonlinearities can evolve to the trans-scale boundary, thus make this scale coupling method invalid. A methodological strategy considering adaptive trans-scale boundary is proposed to deal with the extension of local nonlinear response during analyses. With application of the multi-scale modeling and computation strategy developed in this paper, failure processes of a beam component with defect and a longitudinal stiffening truss are analyzed. Results show that, damage evolution has acceleration effect on macroscopic deterioration of structure property, and localization phenomenon of damage evolution is obvious. Comparison of failure route of upper and bottom joints of the truss shows different deterioration process.

10

Analiza odkształcenia i powstawania pęknięć w procesie kucia stopu aluminium 6060

Kukuryk M.

Rudy i Metale Nieżelazne

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2013

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R. 58, nr 10

564--569

PL

W artykule przedstawiono analizę przestrzennego stanu odkształcenia i naprężenia dla procesu kucia wydłużającego stopu aluminium 6060 z wykorzystaniem metody elementów skończonych. Przedstawiono rezultaty prac związanych z symulacją schematu płynięcia metalu i zjawisk cieplnych w procesie kucia na gorąco w kowadłach płaskich i kształtowych. Wyniki badań uzupełniono prognozowaniem pęknięć podczas kucia. Analizę numeryczną wykonano z wykorzystaniem komercyjnego programu DEFORM 3D, składającego się z części mechanicznej, termicznej i prognozowania pękania. Porównanie teoretycznych i eksperymentalnych rezultatów badań wskazuje na dobrą ich zgodność.

EN

A three-dimensional finite element (FEM) analysis has been performed to quantitatively describe the cogging process of 6060 aluminum alloy. The results of simulation studies of the metal flow pattern and thermal phenomena in the hot forging process in flat and shaped anvils. The results of the studies have been complemented with the prediction of ductile fractures during forging. For the numerical modelling have been employed a commercial program DEFORM-3D with thermomechanic and damage evolution coupled. Good agreement between theoretical and experimental results was observed.

11

Analiza odkształcenia i prognozowanie pękania w procesie kucia stali narzędziowej

Kukuryk B.

Hutnik, Wiadomości Hutnicze

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2013

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Vol. 80, nr 10

712--715

PL

W pracy przedstawiono wyniki termomechanicznej symulacji procesu kucia wydłużającego stali narzędziowej w kowadłach płaskich i kształtowych z zastosowaniem metody elementów skończonych. Analizę dla przestrzennego stanu odkształcenia oparto o rozkład intensywności odkształcenia, naprężeń średnich i temperatury. Wyniki badań uzupełniono o prognozowanie pękania materiału podczas kucia. Analizę numeryczną wykonano z użyciem komercyjnego programu DEFORM 3D, składającego się z części mechanicznej, termicznej i prognozowania pękania. Porównanie teoretycznych i eksperymentalnych rezultatów badań wskazuje na dobrą ich zgodność.

EN

Finite element method was employed to model plastic flow and heat transfer in the cogging process of tool steel in flat and shaped anvils. The analysis for three-dimensional state of strain was based on distribution of the effective strain, mean stresses and temperature. The results of the studies have been complemented with the prediction of ductile fractures during forging. For the numerical modelling have been employed a commercial program DEFORM-3D with thermo-mechanic and damage evolution coupled. Good agreement between theoretical and experimental results was observed.

12

Numeryczna analiza rozwoju mikrouszkodzeń w elemencie z defektem w postaci nieciągłości strukturalnej

Kossakowski P.

Budownictwo i Architektura

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2013

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Vol. 12, nr 1

235--242

PL

W artykule przedstawiono wyniki numerycznej analizy ewolucji mikrouszkodzeń w elemencie z defektem. Symulacja zostala przeprowadzona w oparciu o model materiałowy Gursona-Tvergaarda-Needlemana, uwzględniający wpływ mikrouszkodzeń na wytrzymałość materiału. Rozpatrywano element tarczowy z centralnym otworem, modelującym nieciągłość strukturalną, która może powstać w elemencie konstrukcyjnym w wyniku korozji. Przeprowadzona symulacja umożliwiła zbadanie zjawiska powstawania i ewolucji mIkrouszkodzeń w stali 52353R, co w przypadku analizowanego elementu pozwoliło na detekcję inicjacji milkropękania oraz jego rozwoju w obszarze narażonym na uszkodzenie.

EN

The numerical analysis of microdamage evolution in S235JR steel is presented in the paper. The simulation was performed basing on the Gurson-TvergaardNeedleman material model which takes into consideration the influence of microdamage to the material strength. The plate element with a central hole was considered. It modelled the structure discontinuity which may occur in structural element due to such a phenomenon as corrosion. The numerical simulation and analysis of micro-damage evolution for this element made of S235JR steel was carried out, which allowed to show and detect the microcrack initiation and area subjected to final failure.

13

A Damageable Spring

Chipman J. C., Roux A., Shillor M., Sofonea M.

Machine Dynamics Research

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2011

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Vol. 35, No. 1

82-96

EN

The evolution of material damage in a nonlinear spring is modeled, analyzed, and numerically simulated. The material damage is described by a damage function whose evolution depends on the mechanical energy in the system and the damage threshold. The model is in the form of two coupled nonlinear ordinary differential equations. The existence of the unique solution is proved using arguments for evolutionary equations with maximal monotone operators, differential equations, and fixed points. The scaling properties of the model are discussed. A numerical algorithm for the problem is presented and four simulations of the system behavior depicted. In particular, the changes in the oscillations of the system as damage progresses are shown.

14

Cellular automata in damage mechanics: creep rupture case

Chrzanowski M., Nowak K.

Archives of Mechanics

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2007

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Vol. 59, nr 4-5

329-339

EN

In the paper, the cellular automata (CA) method for the description of damage formation introduced in [I], is extended over creep circumstance by introducing grain boundaries. The material structure is modelled by Voronoi-like tessellation with distance measure corresponding to Moore neighbourhood. The size of Representative Volume Element (RVE) is determined by the number of grains, seed nodes of which are distributed by a homogeneous Poisson point process. The global number of cells to be damaged is subjected to the mass conservation law. Additionally, probabilistic rules, which cause the damage to develop in form of microcracks, microvoids, large voids or a combination of voids and cracks are used. Loading through imposed deformation of RVE is continued until damage cells form a continuous path spanning opposite sides of RVE. In terms of continuum damage mechanics, this situation corresponds to the damage parameter reaching the critical value in a given material point. The results obtained in this paper for polycrystalline material have been compared with a material of homogenous structure.