scholarly journals LOFT pressurizer pressure relief piping system stress analysis and fatigue life report

1978 ◽  
Author(s):  
J.W. Muffett
Keyword(s):  
Fatigue Life ◽  
Stress Analysis ◽  
Piping System ◽  
Pressure Relief

Application of Draft Regulatory Guide DG-1144 Guidelines for Environmental Fatigue Evaluation to a BWR Feedwater Piping System

2007 ◽  
Author(s):  
Hardayal S. Mehta ◽  
Henry H. Hwang
Keyword(s):  
Fatigue Life ◽  
Thermal Cycle ◽  
Light Water Reactor ◽  
Piping System ◽  
Low Alloy Steel ◽  
Light Water ◽  
Asme Code ◽  
Fatigue Evaluation ◽  
Cycle Diagram ◽  
Analytical Expressions

Recently published Draft Regulatory Guide DG-1144 by the NRC provides guidance for use in determining the acceptable fatigue life of ASME pressure boundary components, with consideration of the light water reactor (LWR) environment. The analytical expressions and further details are provided in NUREG/CR-6909. In this paper, the environmental fatigue rules are applied to a BWR feedwater line. The piping material is carbon steel (SA333, Gr. 6) and the feedwater nozzle material is low alloy steel (SA508 Class 2). The transients used in the evaluation are based on the thermal cycle diagram of the piping. The calculated fatigue usage factors including the environmental effects are compared with those obtained using the current ASME Code rules. In both cases the cumulative fatigue usage factors are shown to be less than 1.0.

Study on Reliability Assessment and Mechanics Behavior of Slab Culvert under Heavy Train

2011 ◽  
Vol 90-93 ◽  
pp. 1157-1161
Author(s):  
Qi Cai Wang ◽  
Rong Ling Zhang ◽  
Li Na Ma ◽  
You Xing Wei
Keyword(s):  
Fatigue Life ◽  
Corrosion Rate ◽  
Stress Analysis ◽  
Fatigue Test ◽  
Failure Probability ◽  
Reliability Assessment ◽  
Heavy Haul Train ◽  
Starting Point ◽  
Heavy Haul ◽  
Strain Stress

Abstract：The paper takes heavy haul train existing slab culvert disease and the research status for starting point, researches and analyzes the reliability assessment of slab culvert and fatigue test under heavy haul train. Different corrosion rate and reinforced section failure probability and reliable probability relations is researched as the emphasis . Strain-stress relations and slab culvert reinforced load are studied by the fatigue test , drawn the fatigue life of tensile steel. The research provides a reference for the stress analysis of slab culvert under the point supported conditions.

Fatigue Life Analysis of an Automotive Tensioner Through Strain-Life Approach

2015 ◽  
Author(s):  
Maryam Talimi ◽  
Jean W. Zu
Keyword(s):  
Fatigue Life ◽  
Stress Analysis ◽  
Drive System ◽  
Life Assessment ◽  
Fatigue Properties ◽  
Fatigue Life Assessment ◽  
Front End ◽  
Life Analysis ◽  
Fatigue Life Analysis ◽  
Prediction Approach

In this paper, fatigue life assessment of a tensioner is studied through dynamic load analysis, stress analysis, and stress-life fatigue analysis approach. Tensioner is a critical part of an automotive front end accessory drive system, providing pre-tension to the belt. The front end accessory drive systems are responsible for transmitting power from the crankshaft to the accessory components. Due to the engine pulsation, components of the accessory drive including the tensioner are subjected to dynamic loads leading to fatigue failure. The fatigue life assessment of a mechanical component highly depends on loading, geometry, and material properties. In addition, the dynamic behavior of the front end accessory drive is complicated due to coupling between several modes of vibrations in belt, pulleys, and the tensioner arm. Duo to the complexity of the parameters involved and complicated dynamics, the fatigue life analysis of FEAD components is a challenging task. This paper includes three main parts, namely stress analysis, fatigue properties prediction, and life estimation. The dynamic analysis of a generic front end accessory drive system is performed in order to obtain effective loads on the tensioner. Stress state for the tensioner in case of different applied loading conditions is performed via a series of Finite Element (FE) analyses, and the critical region of the part is determined. Finally, fatigue life is estimated through strain-life approach. Modest work has been found in this area providing a comprehensive solution to the fatigue life investigation of power train components. The present study offers a comprehensive modeling approach which predicts the automative tensioner lifetime. The lifetime of any FEAD system components can be determined using the developed fatigue life prediction approach.

Simulation of Fatigue Life Prediction and Enhancement of Connecting Rod of Car Engine

2012 ◽  
Vol 557-559 ◽  
pp. 2410-2414
Author(s):  
Ojo Kurdi ◽  
Mohd Arif Bin Mat Norman ◽  
Ian Yulianti ◽  
Muhammad Nizam Bin Md Rashid
Keyword(s):  
Finite Element Method ◽  
Fatigue Life ◽  
Stress Analysis ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Connecting Rod ◽  
Modified Model ◽  
Stress Region ◽  
Life Enhancement ◽  
Fatigue Life Enhancement

This paper investigates the fatigue life prediction and fatigue life enhancement of connecting rods of car engine. The fatigue life prediction was simulated by analyzing the stress occur in the connecting rod and then simulate the fatigue life prediction. The stress analysis was done by using finite element method. The results obtained from stress analysis is used as the input to simulate the fatigue life using stress-life method. The simulation was done for two models, the existing model and modified model. The modified model is the existing model with increased thickness in the highest stress region. The results show that the modified model has an improved fatigue life up to 231% compared to that of the existing model.

Effect of Loading on Stress Intensification Factors

2005 ◽  
Vol 128 (1) ◽  
pp. 33-38
Author(s):  
Rudolph J. Scavuzzo
Keyword(s):  
Fatigue Life ◽  
Evaluation Method ◽  
Fatigue Testing ◽  
Plastic Material ◽  
Strain Curve ◽  
Correct Prediction ◽  
Piping System ◽  
Testing Methods ◽  
Strain Cycle ◽  
Perfectly Plastic

The basic objective of this investigation is to determine the effect of loading on the stress intensification factors of Markl’s fatigue evaluation method for metal piping. Markl’s method is based on the fatigue testing of 4 in. schedule 40 carbon steel cantilever piping. Subsequent testing using a four-point loading showed that the S-N data were different from that predicted by the procedure and equation developed by Markl. Markl’s method is based on determining the elastic-plastic forces in a piping system by multiplying the elastic system stiffness by the actual deflection. In this manner a fictitious force is calculated to determine piping stresses assuming the elastic beam bending equation, Mc/I, applies even in partially plastic pipes. Previous analytical work on this topic by Rodabaugh and Scavuzzo (“Fatigue of Butt Welded Pipe and the Effect of Testing Methods–Report 2: Effect of Testing Methods on Stress Intensification Factors,” Welding Research Bulletin 433, July 1998) showed that these measured differences should occur between cantilever and four-point tests using Markl’s method. The basic assumption in this analytical comparison is that strain-cycle correlations lead to the correct prediction of fatigue life. Using the measured alternating strain, both types of test geometries lead to the same prediction of fatigue life using these strain-cycle correlations. In this study, the same analytical assumptions used by Rodabaugh and Scavuzzo (above) are applied to a pipe where the load is varied from a four-point loading through its extremes. Loads were varied from a cantilever to an end moment by changing the dimensions of four-point loading. Also, the shape of a bilinear stress-strain curve was varied from a perfectly plastic material to various degrees of work hardening by increasing the tangent modulus in the plastic regime. The results of the study indicate that Markl’s method is conservative by predicting too short a fatigue life for four-point loading for a given stress. As indicated by this study, the differences can be very large in the low-cycle regime for a perfectly plastic material and for a four-point loading approaching an end moment. Thus, piping could be over designed with unnecessary conservatism using the current ASME Code method based on stress intensification factors.

Stress Relief in Solder Joints Due to the Application of a Flex Circuit

1991 ◽  
Vol 113 (3) ◽  
pp. 240-243 ◽  
Author(s):  
E. Suhir
Keyword(s):  
Fatigue Life ◽  
Stress Analysis ◽  
Solder Joints ◽  
Stress Relief ◽  
Physical Design ◽  
Thermal Contraction ◽  
Analysis Model ◽  
Rigid Substrate

A stress analysis model is developed to assess the stresses in solder joints caused by thermal contraction mismatch between a low expansion flex-circuit (FC) and a high expansion rigid substrate. It is shown that application of low expansion FCs can result in significant stress relief for solder joints. This is due to the fact that the force acting on a joint cannot exceed the buckling force for the adjacent portion of the FC. It is shown that the strains in solder joints interconnecting FCs to rigid substrates can be made very small, thereby resulting in a substantially longer fatigue life of the interconnection. In the executed example these strains are about two orders of magnitude smaller, than in the case of a rigid board. The obtained results can be utilized as guidance in physical design of assemblies with FCs.

Influence of Local Wall Thinning and Support Stiffness in Piping Systems on Safety Assessments for Dynamic Loading

2014 ◽  
Author(s):  
Klaus Kerkhof ◽  
Fabian Dwenger ◽  
Gereon Hinz ◽  
Siegfried Schmauder
Keyword(s):  
Stress Analysis ◽  
Response Spectrum ◽  
System Response ◽  
Piping System ◽  
Load Bearing ◽  
Wall Thinning ◽  
Safety Margins ◽  
Piping Systems ◽  
Bearing Behavior ◽  
Local Wall Thinning

The load bearing behavior of piping systems depends considerably on support distances and stiffness as well as cross section characteristics. Stiffness of supports can often be defined only with difficulty by applying simplified procedures or guidelines based on assumptions. Load cases can be estimated quite well, but the safety assessment of a piping system can only be as reliable as the system model can realistically describe the present support stiffness or imperfections e.g. local wall thinning. As a consequence, the prediction of the system response may be poor. It is likely that calculated frequencies differ from natural frequencies determined experimentally. These frequency shifts lead to unrealistic predictions of stress analysis. Examples for overestimations and underestimations of stress analysis are given regarding the load case earthquake, depending on whether the frequency shift runs into or out of the plateau of the applied floor response spectrum. The influence of local wall thinning on modal characteristics is investigated. Conservative estimations of the influence on the load bearing behavior regarding severe local wall thinning are given. For fatigue checks the linear response of an experimental piping system is calculated and safety margins are demonstrated by comparing calculated with experimental results.

scholarly journals Thermal Stress Analysis of Process Piping System Installed on LNG Vessel Subject to Hull Design Loads

2020 ◽  
Vol 8 (11) ◽  
pp. 926
Author(s):  
Se-Yun Hwang ◽  
Min-Seok Kim ◽  
Jang-Hyun Lee
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Evaluation Model ◽  
Element Model ◽  
Piping System ◽  
Wave Load ◽  
Element Analysis ◽  
Expansion Joints ◽  
Load Conditions

In this paper, the procedure for the strength evaluation of the piping system installed on liquefied natural gas (LNG) carriers is discussed. A procedure that accounts for the ship’s wave load and hull motion acceleration (as well as the deformation due to the thermal expansion and contraction experienced by the hull during seafaring operations) is presented. The load due to the temperature and self-weight of the piping installed on the deck is also considered. Various operating and load conditions of the LNG piping system are analyzed. Stress analysis is performed by combining various conditions of sustained, occasional, and expansion loads. Stress is assessed using finite element analysis based on beam elements that represent the behavior of the piping. The attributes of the piping system components (such as valves, expansion joints, and supports) are represented in the finite element model while CAESAR-II, a commercial software is used for finite element analysis. Component modeling, load assignment, and load combinations are presented to evaluate pipe stresses under various load conditions. An evaluation model is selected for the piping arrangement of LNG and the evaluated stress is compared with the allowable stress defined by the American Society of Mechanical Engineers (ASME).

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