Micromechanical Modeling of Dual-Phase DP600 Steel Sheet Plastic Behavior Based on a Representative Volume Element Defined from the Real Microstructure

2018 ◽  
Vol 930 ◽  
pp. 293-298 ◽  
Author(s):  
Gustavo Coqui Barbosa ◽  
Luciano Pessanha Moreira ◽  
Lílian Barros da Silveira ◽  
Fabiane Roberta Freitas da Silva ◽  
Marcelo Costa Cardoso

Dual-phase steels offer very attractive combinations of strength and ductility owing to the coexistence of different microstructures components and their interactions. These steels are suitable to the automotive industry due to their improved impact resistance increasing the passenger safety along with the vehicle weight reduction. The properties of the dual-phase steels are attributed to the chemical composition, type, size, amount and spatial distribution of different phases that can be obtained during thermomechanical treatments, namely, ferrite and martensite. In this work, the microstructure of as-received DP600 cold rolled steel sheet with 1.2 mm nominal thickness was firstly characterized by means of scanning electron microscopy technique. Then, a representative volume element was obtained from the DP600 microstructure and a micromechanical finite element model is proposed considering the steel chemical composition, average ferrite grain size, martensite volume fraction and mechanical properties of both ferrite and martensite phases. The uniaxial tension loading was simulated by assuming either plane-stress and plane-strain conditions. The numerical predictions corresponding to the plane-strain model are in good agreement with the experimental true stress-strain curve determined along the sheet rolling direction. The proposed finite element micromechanical approach based on the real microstructure proved to be an important tool to evaluate both local and overall behaviors of DP600 steel grade.

2016 ◽  
Vol 101 ◽  
pp. 27-39 ◽  
Author(s):  
Maedeh Amirmaleki ◽  
Javad Samei ◽  
Daniel E. Green ◽  
Isadora van Riemsdijk ◽  
Lorna Stewart

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Siva Bhaskara Rao Devireddy ◽  
Sandhyarani Biswas

The aim of present work is focused on the evaluation of elastic and thermal properties of unidirectional fiber-reinforced polymer composites with different volume fractions of fiber up to 0.7 using micromechanical approach. Two ways for calculating the material properties, that is, analytical and numerical approaches, were presented. In numerical approach, finite element analysis was used to evaluate the elastic modulus and thermal conductivity of composite from the constituent material properties. The finite element model based on three-dimensional micromechanical representative volume element (RVE) with a square and hexagonal packing geometry was implemented by using finite element code ANSYS. Circular cross section of fiber and square cross section of fiber were considered to develop RVE. The periodic boundary conditions are applied to the RVE to calculate elastic modulus of composite. The steady state heat transfer simulations were performed in thermal analysis to calculate thermal conductivity of composite. In analytical approach, the elastic modulus is calculated by rule of mixture, Halpin-Tsai model, and periodic microstructure. Thermal conductivity is calculated analytically by using rule of mixture, the Chawla model, and the Hashin model. The material properties obtained using finite element techniques were compared with different analytical methods and good agreement was achieved. The results are affected by a number of parameters such as volume fraction of the fibers, geometry of fiber, and RVE.


2014 ◽  
Vol 553 ◽  
pp. 22-27
Author(s):  
Ling Li ◽  
Lu Ming Shen ◽  
Gwénaëlle Proust

A texture-based representative volume element (TBRVE) model is developed for the three-dimensional crystal plasticity (CP) finite element simulations of the Bauschinger effect (BE) of polycrystalline aluminium alloy 7075 (AA7075). In the simulations, the grain morphology is created using the Voronoi tessellation method with the material texture systematically discretised from experiment. A modified CP constitutive model, which takes into account the backstress, is used to simulate the BE during cyclic loading. The model parameters are calibrated using the first cycle stress-strain curve and used to predict the mechanical response to the cyclic saturation of AA7075. The results indicate that the proposed TBRVE CP finite element model can effectively capture the BE at the grain level.


Author(s):  
Seyed Hamid Reza Sanei ◽  
Randall Doles

Abstract The aim of this study is to present a representative volume element (RVE) for nanocomposites with different microstructural features using a stochastic finite element approach. To that end, computer-simulated microstructures of nanocomposites were generated to include a variety of uncertainty present in geometry, orientation, and distribution of carbon nanotubes. Microstructures were converted into finite element models based on an image-based approach for the determination of elastic properties. For each microstructure type, 50 realizations of synthetic microstructures were generated to capture the variability as well as the average values. Computer-simulated microstructures were generated at different length scales to determine the change in mechanical properties as a function of length scale. A representative volume element is defined at a length scale beyond which no change in variability is observed. The results show that there is no universal RVE applicable to all properties and microstructures; however, the RVE size is highly dependent on microstructural features. Microstructures with agglomeration tend to require larger RVE. Similarly, random microstructures require larger RVE when compared with aligned microstructures.


Author(s):  
Bijan Mohammadi ◽  
AmirSajjad Khoddami

Solid particle erosion is one of the main failure mechanisms of a compressor blade. Thus, characterization of this damage mode is very important in life assessment of the compressor. Since experimental study of solid particle erosion needs special methods and equipment, it is necessary to develop erosion computer models. This study presents a coupled temperature–displacement finite element model to investigate damage of a compressor blade due to multiple solid particles erosion. To decrease the computational cost, a representative volume element technique is introduced to simulate simultaneous impact of multiple particles. Blade has been made of Ti-6Al-4V, a ductile titanium-based alloy, which is impacted by alumina particles. Erosion finite element modeling is assumed as a micro-scale impact problem and Johnson–Cook constitutive equations are used to describe Ti-6Al-4V erosive behavior. In regard to a wide variation range in thermal conditions all over the compressor, it is divided into three parts (first stages, middle stages, and last stages) in which each part has an average temperature. Effective parameters on erosive behavior of the blade alloy, such as impact angle, particles velocity, and particles size are studied in these three temperatures. Results show that middle stages are the most critical sites of the compressor in terms of erosion damage. An exponential relation is observed between erosion rate and particles velocity. The dependency of erosion rate on size of particles at high temperatures is indispensable.


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