The Influence of Initial Residual Stress State on the Steady State Behaviour of Cyclically Loaded Coupled Contacts

2011 ◽  
Author(s):  
Robert Flicek ◽  
Daniele Dini ◽  
David A. Hills
Keyword(s):  
Residual Stress ◽  
Frictional Contact ◽  
Contact Problems ◽  
Coupled Problems ◽  
Strongly Coupled ◽  
Initial Residual Stress ◽  
Residual Stress State ◽  
Initial Load ◽  
State Behaviour ◽  
Steady State Behaviour

The Melan’s shakedown theorem applies to uncoupled frictional contact problems, but is known formally not to apply in the case of coupled contacts. In this paper we look at two example coupled problems (one very strongly coupled) in detail and show that, in fact, for these specific cases, shakedown does occur for a range of initial load states.

Effect of Initial Residual Stress on Stress Relaxation in Cold-Drawn Steel Rods

2010 ◽  
Vol 652 ◽  
pp. 227-232
Author(s):  
Jesus Ruiz-Hervias ◽  
Jose M. Atienza ◽  
Javier R. Santisteban ◽  
Manuel Elices Calafat
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Residual Stresses ◽  
Cross Section ◽  
Stress Relaxation Behavior ◽  
Relaxation Experiment ◽  
Initial Residual Stress ◽  
Residual Stress State ◽  
Residual Strains

This work shows the effect of the initial residual stress state on the stress relaxation behavior of cold-drawn steel rods. The evolution of residual strains at several locations along the rod diameter was measured in-situ by neutron diffraction during a stress relaxation experiment. It was found that if residual stresses are significant, stress relaxation is not homogeneous in the cross-section of the rods. This also explains the higher stress losses found in the rods with high residual stresses.

A Partitioned Formulation for FEM/BEM Coupling in Contact Problems Using Localized Lagrange Multipliers

2014 ◽  
Vol 618 ◽  
pp. 23-48
Author(s):  
Jose A. González ◽  
K.C. Park ◽  
Ramon Abascal
Keyword(s):  
Finite Element Method ◽  
Lagrange Multipliers ◽  
Frictional Contact ◽  
State Of The Art ◽  
Contact Problems ◽  
Coupled Systems ◽  
The Finite Element Method ◽  
Numerical Techniques ◽  
Strongly Coupled ◽  
Software Modularity

This paper presents a state-of-the-art in the use of localized Lagrange multipliers (LLMs)for 3D frictional contact problems coupling the Finite Element Method (FEM) and the BoundaryElement Method (BEM). Resolution methods for the contact problem between non-matching mesheshave traditionally been based on a direct coupling of the contacting solids using classical Lagrangemultipliers. These methods tend to generate strongly coupled systems that require a deep knowledgeof the discretization characteristics on each side of the contact zone complicating the process ofmixing different numerical techniques. In this work a displacement contact frame is inserted betweenthe FE and BE interface meshes, discretized and finally connected to the contacting substructuresusing LLMs collocated at the mesh-interface nodes. This methodology will provide a partitionedformulation which preserves software modularity and facilitates the connection of non-matching FEand BE meshes.

Residual stress state behaviour under fatigue loading in pipeline welded joints

2001 ◽  
Vol 36 (5) ◽  
pp. 465-472 ◽  
Author(s):  
M P Cindra Fonseca ◽  
J. R Teodósio ◽  
J. M A Rebello ◽  
A B Correia da Cruz
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Welded Joints ◽  
Fatigue Loading ◽  
Residual Stress State ◽  
State Behaviour

Micro-Macro Modeling of the Isothermal Steady-State Behaviour of Semi-Solids

2004 ◽  
Vol 7 (1-2) ◽  
pp. 177-194 ◽  
Author(s):  
Véronique Favier ◽  
Carole Rouff ◽  
Régis Bigot ◽  
Marcel Berveiller ◽  
Marc Robellet
Keyword(s):  
Steady State ◽  
Macro Modeling ◽  
State Behaviour ◽  
Steady State Behaviour

scholarly journals Process Signature for Laser Hardening

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 465
Author(s):  
Friedhelm Frerichs ◽  
Yang Lu ◽  
Thomas Lübben ◽  
Tim Radel
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Heating Time ◽  
Temperature Gradients ◽  
Laser Hardening ◽  
Thermal Loads ◽  
Zero Crossing ◽  
Residual Stress State ◽  
Stress Curve ◽  
Process Signature

During many manufacturing processes for surface treatment of steel components heat will be exchanged between the environment and the workpiece. The heat exchange commonly leads to temperature gradients within the surface near area of the workpiece, which involve mechanical strains inside the material. If the corresponding stresses exceed locally the yield strength of the material residual stresses can remain after the process. If the temperature increase is high enough additionally phase transformation to austenite occurs and may lead further on due to a fast cooling to the very hard phase martensite. This investigation focuses on the correlation between concrete thermal loads such as temperature and temperature gradients and resulting modifications such as changes of the residual stress, the microstructure, and the hardness respectively. Within this consideration the thermal loads are the causes of the modifications and will be called internal material loads. The correlations between the generated internal material loads and the material modifications will be called Process Signature. The idea is that Process Signatures provide the possibility to engineer the workpiece surface layer and its functional properties in a knowledge-based way. This contribution presents some Process Signature components for a thermally dominated process with phase transformation: laser hardening. The target quantities of the modifications are the change of the residual stress state at the surface and the position of the 1st zero-crossing of the residual stress curve. Based on Finite Element simulations the internal thermal loadings during laser hardening are considered. The investigations identify for the considered target quantities the maximal temperature, the maximal temperature gradient, and the heating time as important parameters of the thermal loads.

Elastoplastic Frictional Contact Study on Interference Fits of Compressor

2011 ◽  
Vol 211-212 ◽  
pp. 535-539
Author(s):  
Ai Hua Liao
Keyword(s):  
Stress Distribution ◽  
Contact Stress ◽  
Frictional Contact ◽  
Contact Problems ◽  
Boundary Problems ◽  
Interference Fit ◽  
Parametric Variational Principle ◽  
Design And Manufacturing ◽  
Contact Stress Distribution ◽  
Fit Tolerance

The impeller mounted onto the compressor shaft assembly via interference fit is one of the key components of a centrifugal compressor stage. A suitable fit tolerance needs to be considered in the structural design. A locomotive-type turbocharger compressor with 24 blades under combined centrifugal and interference-fit loading was considered in the numerical analysis. The FE parametric quadratic programming (PQP) method which was developed based on the parametric variational principle (PVP) was used for the analysis of stress distribution of 3D elastoplastic frictional contact of impeller-shaft sleeve-shaft. The solution of elastoplastic frictional contact problems belongs to the unspecified boundary problems where the interaction between two kinds of nonlinearities should occur. The effect of fit tolerance, rotational speed and the contact stress distribution on the contact stress was discussed in detail in the numerical computation. The study play a referenced role in deciding the proper fit tolerance and improving design and manufacturing technology of compressor impellers.

Power Limits in Stepping and other Small Brushless Motors — A Simple Approach Using the Blondel Circle Diagram

1988 ◽  
Vol 25 (3) ◽  
pp. 251-264
Author(s):  
A. Hughes ◽  
D. W. J. Pulle
Keyword(s):  
Steady State ◽  
Simple Approach ◽  
Brushless Motors ◽  
Undergraduate Level ◽  
State Behaviour ◽  
Power Limits ◽  
Circle Diagram ◽  
Steady State Behaviour

Brushless drives are important, but are often thought to be difficult to treat quantitatively at the undergraduate level. The Blondel circle diagram is shown to be ideal for illuminating the steady-state behaviour and limitations of small brushless system, at a level suitable for undergraduate courses.

scholarly journals Sensitivity Analysis for Frictional Contact Problems with Large Deformation.

1999 ◽  
Vol 65 (637) ◽  
pp. 1859-1866
Author(s):  
Xian CHEN ◽  
Kazuhiro NAKAMURA ◽  
Masahiko MORI ◽  
Toshiaki HISADA
Keyword(s):  
Sensitivity Analysis ◽  
Large Deformation ◽  
Frictional Contact ◽  
Contact Problems

scholarly journals Influence of Steel Grain Size on Residual Stress in Grinding Processing

2010 ◽  
Vol 638-642 ◽  
pp. 2389-2394 ◽  
Author(s):  
Masahide Gotoh ◽  
Katsuhiro Seki ◽  
M. Shozu ◽  
Hajime Hirose ◽  
Toshihiko Sasaki
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Grain Size ◽  
Stress State ◽  
Mechanical Grinding ◽  
Fine Grained ◽  
Residual Stress State ◽  
Analysis Methods ◽  
Average Grain Size ◽  
Fine Grained Steels

The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 μm and 15μm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ33, the stress of NFG was compression, though that of SM490 was tension.

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