Fatigue Failure Analysis on Key Components of Bladder Accumulators

2015 ◽  
Vol 750 ◽  
pp. 363-370
Author(s):  
Ya Ping Niu ◽  
Bing Bing Chen
Keyword(s):  
Failure Analysis ◽  
Fatigue Failure ◽  
High Stress ◽  
Peak Stress ◽  
Optical Microscope ◽  
Metallographic Analysis ◽  
The Finite Element Method ◽  
Valve Body ◽  
Support Ring ◽  
Initiation And Propagation

Fatigue failure analysis on key components of bladder accumulators was conducted. Failure fracture of the key components, which included the shell, the support ring and the oil inlet valve body in the accumulators, was investigated by optical microscope (OM) scanning electron microscope (SEM). According to the metallographic analysis and micro-hardness determination at the crack profile, crack initiation and propagation direction was confirmed. By simulation using the finite element method, it was detected that the peak stress of the key components applied on the contact surfaces. Obvious plastic deformation was observed at the region with high stress. However, the fatigue crack did not initiate at the contact surface, but occurred on the second high stress area without contact.

Development of Design Curve for Sweepolet Subjected to Acoustic Induced Vibration

2016 ◽  
Author(s):  
Yuqing Liu ◽  
Philip Diwakar ◽  
Dan Lin ◽  
Ismat Eljaouhari ◽  
Ajay Prakash
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Fatigue Failure ◽  
High Stress ◽  
Peak Stress ◽  
Acoustic Energy ◽  
Piping System ◽  
Element Analysis ◽  
Design Curve ◽  
High Stress Concentration

High acoustic energy has the potential to cause severe Acoustic Induced Vibration (AIV) that leads to fatigue failure at high stress concentration regions such as fittings in a piping system. Sweepolet fittings have been extensively used as mitigation to counteract the risk of fatigue failure caused by AIV. The advantages of a sweepolet are its integrally reinforced contoured body and low stress concentration. However, there are inconsistencies in published standards and regarding the design limits for sweepolet subjected to AIV. In this paper, Finite Element Analysis is conducted to simulate high frequency pipe shell wall vibration caused by acoustic energy inside the pipe. Peak stress and the associated minimum fatigue life are calculated for sweepolet and sockolet under the same acoustic excitation. By comparing the stress level to that of a sockolet whose design limit to AIV had been published, the design curve and fatigue life equation for sweepolet are developed.

Procedure and Discussion of Failure Analysis in Iron-Steel Materials

2014 ◽  
Vol 556-562 ◽  
pp. 261-264
Author(s):  
Zhi Gang Wang ◽  
Lu Dan Shi ◽  
Min Jing ◽  
Yong Xu
Keyword(s):  
Failure Analysis ◽  
Hot Forging ◽  
High Hardness ◽  
Optical Microscope ◽  
Metallographic Analysis ◽  
Good Teaching ◽  
H13 Steel ◽  
Quenching Temperature ◽  
Scan Electronic Microscope ◽  
Electronic Microscope

The failure analysis of the H13 steel hot-forging mould is the main content in the open experiment. The scan electronic microscope and the optical microscope are used to analyze the failure workpiece in this experiment. The over-high quenching temperature, the too low drawing temperature, the insufficient drawing time and frequency, the over-high hardness value are the main reasons of fracture failure of the mould. The work environment of the failure materials, the heat treatment processing, the metallographic analysis, the fracture analysis and the using of test standard are the important aspects which the students should know. The students can learn how to analyze problem and how to solve them from the open experiments which is a good teaching try.

Fatigue Microcrack Initiation and Propagation of Aluminum Alloy under Different Stress Level and Stress Ratio

2011 ◽  
Vol 239-242 ◽  
pp. 1495-1500
Author(s):  
Gui Xue Bian ◽  
Yue Liang Chen ◽  
Jian Jun Hu ◽  
Yong Zhang
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Stress Level ◽  
Stress Ratio ◽  
High Stress ◽  
Optical Microscope ◽  
Initiation And Propagation ◽  
Microcrack Initiation ◽  
Stress Ratios ◽  
High Stress Level

The microstructure of fatigue fracture of aluminum alloys under various stresses and stress ratios were studied by optical microscope and scanning electron microscope, and the influences of microstructure features on microcrack initiation and propagation were investigated. The results show that the fatigue microcrack originated from surface or subsurface of specimens. And with the increase of stress ratio, fatigue crack originated from deeper subsurface at the same stress level. With the increase of stress level, fatigue crack originated from shallower subsurface or surface at same stress ratio. There is an increase in crack propagation region as the stress level decreases at the same stress ratio. Increasing of stress ratio, increases crack propagation region under same stress level. Microcrack generally originated from secondary (S phase particles) and larger particles at low stress level and high stress ratio. Microcrack generally originated from larger constituent particles at high stress level and low stress ratio. Microcracks propagation is evidently impeded by grain boundaries at low stress level and high stress ratio.

scholarly journals Fatigue failure analysis of drilling tools for ultra-deep wells in shunbei Block

2018 ◽  
Vol 423 ◽  
pp. 012190
Author(s):  
Biao Liu ◽  
Zhongxi Zhu ◽  
Jun Zhang ◽  
Wanneng Lei ◽  
Baichuan Wu
Keyword(s):  
Failure Analysis ◽  
Fatigue Failure ◽  
Deep Wells ◽  
Drilling Tools

Fatigue Failure Analysis Using the Theory of Critical Distance

2011 ◽  
Vol 462-463 ◽  
pp. 663-667 ◽  
Author(s):  
Ruslizam Daud ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Al Emran Ismail
Keyword(s):  
Stress Concentration ◽  
Fatigue Failure ◽  
Notch Root ◽  
High Stress ◽  
Critical Distance ◽  
Future Research ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Finite Element Analysis ◽  
Elastic Fracture

This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.

An Experimental Study of Cavity Nucleation During Superplastic Deformation

1990 ◽  
Vol 196 ◽  
Author(s):  
Jiang Xinggang ◽  
Cui Jianzhong ◽  
Ma Longxiang
Keyword(s):  
Grain Boundary ◽  
Superplastic Deformation ◽  
Thermomechanical Processing ◽  
High Stress ◽  
High Strength ◽  
Optical Microscope ◽  
Grain Boundary Sliding ◽  
Cavity Nucleation ◽  
High Stress Concentration ◽  
Voltage Electron

ABSTRACTCavity nucleation during superplastic deformation of a high strength aluminium alloy has been studied using a high voltage electron microscope and an optical microscope. The results show that cavities nucleation is due only to superplastic deformation and not to pre-existing microvoids which may be introduced during thermomechanical processing. The main reason for cavity nucleation is the high stress concentration at discontinuties in the plane of the grain boundary due to grain boundary sliding.

Failure Analysis of Hydrogen Corrosion of the Lens Gasket

2010 ◽  
Vol 37-38 ◽  
pp. 462-465
Author(s):  
Xiao Chun Ma ◽  
Guang Fei Xu
Keyword(s):  
High Pressure ◽  
Failure Analysis ◽  
Intergranular Crack ◽  
Optical Microscope ◽  
Corrosion Characteristic ◽  
Hydrogen Corrosion ◽  
Corrosion Depth ◽  
Fertilizer Plant ◽  
Inner Surface ◽  
Hydrogen Blister

The 10MoWVNb steel lens gaskets are widely used for the flange linking of high pressure tube in the synthetic ammonia system in chemical fertilizer plant. The gasket worked in H2-N2-NH3 environment at the temperature of 300°C. It often fails because of hydrogen corrosion. The microstructure and corrosion characteristic of the lens gasket were studied by optical microscope. The results showed that the hydrogen blister appeared preferentially at the interface of inclusions. The corrosion depth was 0.65 millimeter. There were little intergranular crack on inner surface.

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