The Generalized Local Stress Strain (GLOSS) Analysis—Theory and Applications

1991 ◽  
Vol 113 (2) ◽  
pp. 219-227 ◽  
Author(s):  
R. Seshadri
Keyword(s):  
Stress Relaxation ◽  
Low Cycle Fatigue ◽  
Creep Damage ◽  
Local Stress ◽  
Inelastic Strain ◽  
Uniaxial Stress ◽  
Linear Elastic ◽  
Analysis Theory ◽  
Stress Classification

GLOSS analysis is a simple and systematic method for carrying out inelastic evaluations of mechanical components and structures on the basis of two linear elastic finite element analyses. The underlying theory relates redistribution of inelastic stresses at a given location under consideration to the uniaxial stress relaxation process. GLOSS analysis is emerging as a useful technique for determining multiaxial stress relaxation, follow-up, creep damage, inelastic strain concentrations and low-cycle fatigue estimates, limit analysis and issues pertaining to stress-classification.

The Effect of Multiaxiality and Follow-Up on Creep Damage

1990 ◽  
Vol 112 (4) ◽  
pp. 378-385 ◽  
Author(s):  
R. Seshadri
Keyword(s):  
Relaxation Process ◽  
Approximate Method ◽  
Creep Damage ◽  
Local Stress ◽  
Relaxation Response ◽  
Relaxation Model ◽  
Stress Strain ◽  
Theoretical Formulation

A simple approximate method for estimating creep damage in pressure components experiencing multiaxial relaxation and follow-up is presented. The theoretical formulation essentially relates the relaxation process that accounts for multiaxiality and follow-up to the uniaxial relaxation model. The effect of follow-up is determined by studying the relaxation response on the Generalized Local Stress Strain (GLOSS) diagram. A procedure for partitioning creep damage into load and deformation-controlled fractions is also discussed. GLOSS analysis is applied to several component configurations that exhibit follow-up potential.

Inelastic Analysis of Components Using a Modulus Adjustment Scheme

1998 ◽  
Vol 120 (1) ◽  
pp. 1-5 ◽  
Author(s):  
S. Babu ◽  
P. K. Iyer
Keyword(s):  
Low Cycle Fatigue ◽  
Inelastic Strain ◽  
Robust Methods ◽  
Element Analysis ◽  
Linear Elastic ◽  
Inelastic Analysis ◽  
Inelastic Strains ◽  
Adjustment Scheme ◽  
Inelastic Region ◽  
Modulus Reduction

Mechanical components and structures loaded into inelastic region can fail by low cycle fatigue (LCF). Evaluation of inelastic strain is an important stage in the LCF life prediction methodology. Different techniques, viz., experimental methods, elastic-plastic finite element analysis (FEA), and robust methods, can be used to predict inelastic strains. The state predicted by available robust methods does not correspond to equilibrium state of the component. A method called MARS (modulus adjustment and redistribution of stress) based on linear elastic FEA has been developed to obtain equilibrium and kinematic distributions close to the actual one. The proposed method uses an iterative strategy combined with a modulus reduction technique.

Extended GLOSS Method for Determining Inelastic Effects in Mechanical Components and Structures: Isotropic Materials

2000 ◽  
Vol 122 (4) ◽  
pp. 413-420 ◽  
Author(s):  
R. Seshadri ◽  
S. Babu
Keyword(s):  
Stress Relaxation ◽  
Low Cycle Fatigue ◽  
Creep Damage ◽  
Local Region ◽  
Cycle Fatigue ◽  
Multiaxial Stress ◽  
Local Strains ◽  
Isotropic Materials ◽  
Elastic Plastic ◽  
Mechanical Components

The extended GLOSS method of analysis has been presented here that leads to conservative bounds on inelastic local strains. Consequently, the local region constraint parameter λ¯ is determined which can be used to evaluate multiaxial stress relaxation, creep damage, low-cycle fatigue, and elastic-plastic fracture. The method is used to determine inelastic local strains for several component configurations, subjected to mechanical as well as thermal loadings, and then compared with the corresponding inelastic FEA results. [S0094-9930(00)00404-2]

A Highly Accelerated Thermal Cycling (HATC) Test for Solder Reliability Assessment in BGA Packages

2007 ◽  
Author(s):  
X. Long ◽  
I. Dutta ◽  
R. Guduru ◽  
R. Prasanna ◽  
M. Pacheco
Keyword(s):  
Thermal Cycling ◽  
Solder Joints ◽  
Low Cycle Fatigue ◽  
Inelastic Strain ◽  
Fatigue Reliability ◽  
Element Analysis ◽  
Mechanical Cycling ◽  
Experimental Apparatus ◽  
Dependent Strain ◽  
Accelerated Thermal Cycling

A thermo-mechanical loading system, which can superimpose a temperature and location dependent strain on solder joints, is proposed in order to conduct highly accelerated thermal-mechanical cycling (HATC) tests to assess thermal fatigue reliability of Ball Grid Array (BGA) solder joints in microelectronics packages. The application of this temperature and position dependent strain produces generally similar loading modes (shear and tension) encountered by BGA solder joints during service, but substantially enhances the inelastic strain accumulated during thermal cycling over the same temperature range as conventional ATC (accelerated thermal cycling) tests, thereby leading to a substantial acceleration of low-cycle fatigue damage. Finite element analysis was conducted to aid the design of experimental apparatus and to predict the fatigue life of solder joints in HATC testing. Detailed analysis of the loading locations required to produce failure at the appropriate joint (next to the die-edge ball) under the appropriate tension/shear stress partition are presented. The simulations showed that the proposed HATC test constitutes a valid methodology for further accelerating conventional ATC tests. An experimental apparatus, capable of applying the requisite loads to a BGA package was constructed, and experiments were conducted under both HATC and ATC conditions. It is shown that HATC proffers much reduced cycling times compared to ATC.

Low Cycle Fatigue Analysis of Marine Structures

2006 ◽  
Author(s):  
Xiaozhi Wang ◽  
Joong-Kyoo Kang ◽  
Yooil Kim ◽  
Paul H. Wirsching
Keyword(s):  
Welded Joints ◽  
Low Cycle Fatigue ◽  
Prediction Method ◽  
Local Stress ◽  
Cyclic Plasticity ◽  
Cycle Fatigue ◽  
Stress Concentrations ◽  
Damage Prediction ◽  
Marine Structure ◽  
Number Of Cycles

There are situations where a marine structure is subjected to stress cycles of such large magnitude that small, but significant, parts of the structural component in question experiences cyclic plasticity. Welded joints are particularly vulnerable because of high local stress concentrations. Fatigue caused by oscillating strain in the plastic range is called “low cycle fatigue”. Cycles to failure are typically below 104. Traditional welded joint S-N curves do not describe the fatigue strength in the low cycle region (< 104 number of cycles). Typical Class Society Rules do not directly address the low cycle fatigue problem. It is therefore the objective of this paper to present a credible fatigue damage prediction method of welded joints in the low cycle fatigue regime.

scholarly journals Application of Redecision Therapy in Executive Coaching Workshops: Part 2 - A Qualitative Exploration of Participants’ Changes

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Mark Widdowson ◽  
Mil Rosseau
Keyword(s):  
Thematic Analysis ◽  
Personal Growth ◽  
Executive Coaching ◽  
Leadership Skills ◽  
Organisational Development ◽  
Analysis Theory ◽  
Wide Range ◽  
Qualitative Exploration ◽  
Interpersonal Change

This is the second paper of three and describes an investigation into the way that executive coaching as a growing field of organisational development can be based on transactional analysis theory and methods. Twelve participants who had attended a coaching workshop based on Goulding & Goulding’s (1979) redecision therapy approach completed a follow-up Change Questionnaire adapted by the first author from material by Elliott et al (2001) and responses were analysed using thematic analysis (Braun & Clarke 2006). Participants reported experiencing a wide range of personal growth experiences, positive interpersonal change and growth in their business, managerial and leadership skills as a result of participating in the work-shops. Limitations are described including the possible impact of the transferential artefact of wanting to please the workshop facilitator. The thematic analysis findings suggest that such an approach can provide an effective framework for executive coaching workshops.

Developments in Cyclic Analysis and High Temperature Design

2005 ◽  
Author(s):  
Peter Carter ◽  
Douglas L. Marriott
Keyword(s):  
High Temperature ◽  
Power Systems ◽  
Creep Damage ◽  
Limit Load ◽  
Cyclic Stress ◽  
Research Literature ◽  
Stress Classification ◽  
Analysis Technique ◽  
Recent Developments

Design for cyclic loading is emerging as a key question for next generation power systems. Recent developments in techniques for cyclic stress analysis have significant implications for high temperature design. In the same way that limit load analysis is now being used to overcome the difficulties and guesswork of stress classification for steady primary loads, so shakedown and ratcheting analysis can eliminate the more difficult problems of stress classification for cyclic loads. The paper shows how reference stresses defined for shakedown and ratcheting provide rapid and conservative information for design against rupture and creep damage, deformation and strain accumulation, and ratcheting. These techniques will provide additional insights to designers and are likely to augment rather than replace, existing options. These ideas have existed in the research literature for some time, but have now become more accessible by the general industry with a new analysis technique in a commercial finite element code. Examples are given which demonstrate the methodology for nozzles having non-thermal secondary stresses, and prediction of long-term distortion in thermal shock problems.

Strain Based Failure Assessment for Offshore Structures Under Seismic Loading

2008 ◽  
Author(s):  
Wangwen Zhao ◽  
Richard Turner ◽  
Jian Liang
Keyword(s):  
Hot Spots ◽  
Low Cycle Fatigue ◽  
Inelastic Strain ◽  
Seismic Loading ◽  
Offshore Structures ◽  
Fortran Program ◽  
Strain History ◽  
Stress Strain ◽  
Failure Assessment ◽  
Stress Reversals

Under seismic loading, structural hot spots can experience very high levels of stress and many random stress reversals. Conventional stress based methods cannot assess the failure state in detail when stress is beyond the elastic limit and nominal stress reversals are more than double the yield stress. A method has been created to fully reproduce the true stress/ strain history by using 1) generalised Masing’s rule with equivalent cyclic energy dissipation to model cyclic stress/strain relation, 2) Neuber’s method to calculate inelastic strain concentration factor, and 3) relative effective notch factor determined from comparing S-N curves of different joint classes. From this reproduced strain history, strain cycles can be counted and low cycle fatigue analysis can be conducted by using Miner’s rule and by estimating damage from the strain based failure criteria such as Coffin-Mason method. This method has been implemented in a numeric procedure and coded in a FORTRAN program called CYSTRA (as for CYclic STRain Analysis). It takes input of “nominal” random stress history directly from general structural software, linear or non-linear, local or global, and calculates extreme strain and strain cycles at multiple hot spots for the whole structure efficiently. Thus it greatly facilitates failure assessment for offshore structures which can have a large number of hot spots within the structure, unlike mechanical devices commonly assessed in strain based analysis where detailed FE based methods can be used.

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