scholarly journals Finite Element Analysis of Self-Pierce Riveting in Magnesium Alloys Sheets

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
J. F. C. Moraes ◽  
J. B. Jordon ◽  
D. J. Bammann
Keyword(s):  
Magnesium Alloys ◽  
Internal State ◽  
Material Model ◽  
Process Conditions ◽  
Temperature Dependent ◽  
Element Analysis ◽  
State Variable ◽  
Simulation Techniques ◽  
Lightweight Metals ◽  
Joining Process

Conventional fusion joining methods, such as resistance spot welding (RSW), have been demonstrated to be ineffective for magnesium alloys. However, self-pierce riveting (SPR) has recently been shown as an attractive joining technique for lightweight metals, including magnesium alloys. While the SPR joining process has been experimentally established on magnesium alloys through trial and error, this joining process is not fully developed. As such, in this work, we explore simulation techniques for modeling the SPR process that could be used to optimize this joining method for magnesium alloys. Due to the process conditions needed to rivet the magnesium sheets, high strain rates and adiabatic heat generation are developed that require a robust material model. Thus, we employ an internal state variable (ISV) plasticity material model that captures strain-rate and temperature dependent deformation. In addition, we explore various damage modeling techniques needed to capture the piercing process observed in the joining of magnesium alloys. The simulations were performed using a two-dimensional axisymmetric model with various element deletion criterions resulting in good agreement with experimental data. The simulations results of this study show that the ISV material model is ideally suited for capturing the complex physics of the plasticity and damage observed in the SPR of magnesium alloys.

Numerical Analysis of Self-Pierce Riveting of Magnesium Alloys

2013 ◽  
Author(s):  
J. F. C. Moraes ◽  
J. B. Jordon
Keyword(s):  
Magnesium Alloys ◽  
Elevated Temperatures ◽  
Internal State ◽  
Weight Ratio ◽  
High Strength ◽  
Material Model ◽  
The Finite Element Method ◽  
State Variable ◽  
Lightweight Metals ◽  
Joining Process

Regulations all over the world have been pushing vehicle manufacturers to increase fuel economies and decrease green house gas emissions. An effective way to meet these new regulations is to reduce automobile weight through the use of lightweight metals. Magnesium alloys have received recent interest due to its high strength-to-weight ratio. However, conventional fusion joining methods such as resistance spot welding are not effective for magnesium alloys. As such, an attractive joining technique for these lightweight metals is self-pierce riveting (SPR) which is fast, fumeless and does not melt the material. However, SPR must be performed at elevated temperatures because of the low ductility of magnesium alloys at room temperature. Even though the SPR joining process has been established on magnesium alloys, this joining process is not optimized. As such, this study establishes the first attempt at simulating the SPR of magnesium alloys through the use of the finite element method. An internal state variable (ISV) plasticity and damage material model was employed and comparison to experimental results show good results. The results of this study show that the ISV material model is ideally suited for modeling the SPR in magnesium alloys.

scholarly journals Modeling and Analysis of a Screw Fitting Assembly Process Involving a Cast Magnesium Component

2020 ◽  
Vol 7 ◽  
Author(s):  
Kent Salomonsson ◽  
Ales Svoboda ◽  
Nils-Eric Andersson ◽  
Anders E. W. Jarfors
Keyword(s):  
Internal State ◽  
Material Model ◽  
Internal State Variable ◽  
Assembly Process ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
State Variable ◽  
Physically Based ◽  
Cast Magnesium ◽  
Materials Behavior

A finite element analysis of a complex assembly was made. The material description used was a physically based material model with dislocation density as an internal state variable. This analysis showed the importance of the materials’ behavior in the process as there is discrepancy between the bolt head contact pressure and the internals state of the materials where the assembly process allows for recovery. The end state is governed by both the tightening process and the thermal history and strongly influenced by the thermal expansion of the AZ91D alloy.

Temperature-Dependent Fracture Mechanics-Informed Damage Model for Ceramic Matrix Composites

2021 ◽  
Author(s):  
Travis Skinner ◽  
Aditi Chattopadhyay
Keyword(s):  
Fracture Mechanics ◽  
Internal State ◽  
Damage Model ◽  
Ceramic Matrix ◽  
Model Parameters ◽  
Internal State Variable ◽  
Temperature Dependent ◽  
State Variable ◽  
Initiation And Propagation ◽  
Matrix Damage

Abstract This work presents a temperature-dependent reformulation of a multiscale fracture mechanics-informed matrix damage model previously developed by the authors. In this paper, internal state variable theory, fracture mechanics, and temperature-dependent material properties and model parameters are implemented to account for length scale-specific ceramic matrix composite (CMC) brittle matrix damage initiation and propagation behavior for temperatures ranging from room temperature (RT) to 1200°C. A unified damage internal state variable (ISV) is introduced to capture effects of matrix porosity, which occurs as a result of material diffusion around grain boundaries, as well as matrix property degradation due to matrix crack initiation and propagation. The porosity contribution to the unified damage ISV is related to the volumetric strain, and matrix cracking effects are captured using fracture mechanics and crack growth kinetics. A combination of temperature-dependent material properties and damage model parameters are included in the model to simulate effects of temperature on the deformation and damage behavior of 2D woven C/SiC CMC material systems. Model calibration is performed using experimental data from literature for plain weave C/SiC CMC at RT, 700°C, and 1200°C to determine how damage model parameters change in this temperature range. The nonlinear, temperature-dependent predictive capabilities of the reformulated model are demonstrated for 1000°C using interpolation to obtain expected damage model parameters at this temperature and the predictions are in good agreement with experimental results at 1000°C.

Additional Guidance for Inelastic Ratcheting Analysis Using the Chaboche Model

2014 ◽  
Author(s):  
William F. Weitze ◽  
Timothy D. Gilman
Keyword(s):  
Finite Element Analysis ◽  
Stainless Steel ◽  
Cylindrical Shell ◽  
Kinematic Hardening ◽  
Material Model ◽  
Model Parameters ◽  
Temperature Dependent ◽  
Model Refinement ◽  
Element Analysis ◽  
Chaboche Model

This paper builds on PVP2013-98150 by Kalnins, Rudolph, and Willuweit [1], which documented two calibration processes for determining the parameters of the Chaboche nonlinear kinematic hardening (NLK) material model for stainless steel, and tested the material model using a pressurized cylindrical shell subjected to thermal cycling. The current paper examines (1) whether a Chaboche NLK model with only two terms (rather than four as in PVP-98150) is sufficiently accurate, (2) use of the ANSYS program for material model refinement and finite element analysis, and (3) analysis using temperature-dependent NLK model parameters, again using ANSYS.

Microstructure-Level Modeling of Ductile Iron Machining

2002 ◽  
Vol 124 (2) ◽  
pp. 162-169 ◽  
Author(s):  
L. Chuzhoy ◽  
R. E. DeVor ◽  
S. G. Kapoor ◽  
D. J. Bammann
Keyword(s):  
Strain Rate ◽  
Ductile Iron ◽  
Internal State ◽  
Material Model ◽  
The Finite Element Method ◽  
Cast Irons ◽  
Variable Model ◽  
State Variable ◽  
Orthogonal Machining ◽  
Level Model

A microstructure-level model for simulation of machining of cast irons using the finite element method is presented. The model explicitly combines ferritic and pearlitic grains with graphite nodules to produce the ductile iron structure. The behaviors of pearlite, ferrite, and graphite are captured individually using an internal state variable model for the material model. The behavior of each phase is dependent on strain, strain rate, temperature, and amount of damage. Extensive experimentation was conducted to characterize material strain rate and temperature dependency of both ferrite and pearlite. The model is applied to orthogonal machining of ductile iron. The simulation results demonstrate the feasibility of successfully capturing the influence of microstructure on machinability and part performance. The stress, strain, temperature, and damage results obtained from the model are found to correlate well with experimental results found in the literature. Furthermore, the model is capable of handling various microstructures in other heterogeneous materials such as steels.

Simplified Inelastic Time Independent (SITI) Method for Predicting Creep

2007 ◽  
Author(s):  
Jeries J. Abou-Hanna ◽  
Osama Ali ◽  
Venkata Tatikonda ◽  
Timothy E. McGreevy
Keyword(s):  
Creep Behavior ◽  
Inelastic Strain ◽  
Material Model ◽  
Time Dependent ◽  
Computationally Efficient ◽  
Element Analysis ◽  
State Variable ◽  
Creep Analysis ◽  
Inelastic Strains ◽  
Very High

In an effort to address inelastic creep behavior for very high temperature (VHT) applications, a unified state variable material model was used in a time dependent finite element analysis to generate isochronous curves. The resulting isochronous curves were then used in an efficient time-independent plastic analysis to predict the creep behavior of components. This simplified inelastic time-independent (SITI) method can significantly reduce the geometric and load uncertainties, and the over-conservatism in predicting inelastic strain levels. SITI is an effective and computationally efficient approach for predicting inelastic strains of components operating at high and very high temperatures such as the case in the Next Generation Nuclear Plant. This work compares the SITI inelastic strains to those obtained using fully inelastic time-dependent elastic-plastic-creep analysis, and illustrates the effectiveness of the approach in obtaining creep strain predictions without elaborate full inelastic time-dependent simulation.

Finite Element Modeling of Random Multiphase Materials for Micromachining

2007 ◽  
Author(s):  
Y. B. Guo ◽  
S. Anurag
Keyword(s):  
Finite Element ◽  
Internal State ◽  
Chip Morphology ◽  
Depth Of Cut ◽  
Element Analysis ◽  
Multiphase Materials ◽  
State Variable ◽  
Dynamic Mechanical Behavior ◽  
Random Microstructure ◽  
Micro Features

Compared with lithographic techniques, mechanical micromachining is a potential competitive process for fabricating 3D micro/meso components or macro parts with micro-features from diverse materials at high accuracy, efficiency, and low costs, but the size effect induced by the comparable size of microstructures, cutting edge radius, and depth-of-cut results in a plowing dominated process. A methodology to incorporate model random microstructure in finite element analysis (FEA) of micromachining multiphase materials has been developed to understand the plowing, tribological, and heat transfer mechanisms. An internal state variable plasticity model has been developed to model the dynamic mechanical behavior including the effect of randomly distributed microstructure, materials damage and evolution. The simulated process variables including chip morphology, forces, and temperatures agree well with the observed experimental phenomena. The simulation recovers the shearing-plowing transition and increased specific energy in micromachining.

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