scholarly journals Fatigue Resistance and Failure Behavior of Penetration and Non-Penetration Laser Welded Lap Joints

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Xiangzhong Guo ◽  
Wei Liu ◽  
Xiqing Li ◽  
Haowen Shi ◽  
Zhikun Song
Keyword(s):  
Fatigue Resistance ◽  
Failure Modes ◽  
Plate Thickness ◽  
High Stress ◽  
Lap Joints ◽  
Failure Behavior ◽  
Passenger Cars ◽  
Plate Fracture ◽  
The Difference ◽  
Railway Passenger

AbstractPenetration and non-penetration lap laser welding is the joining method for assembling side facade panels of railway passenger cars, while their fatigue performances and the difference between them are not completely understood. In this study, the fatigue resistance and failure behavior of penetration 1.5+0.8-P and non-penetration 0.8+1.5-N laser welded lap joints prepared with 0.8 mm and 1.5 mm cold-rolled 301L plates were investigated. The weld beads showed a solidification microstructure of primary ferrite with good thermal cracking resistance, and their hardness was lower than that of the plates. The 1.5+0.8-P joint exhibited better fatigue resistance to low stress amplitudes, whereas the 0.8+1.5-N joint showed greater resistance to high stress amplitudes. The failure modes of 0.8+1.5-N and 1.5+0.8-P joints were 1.5 mm and 0.8 mm lower lap plate fracture, respectively, and the primary cracks were initiated at welding fusion lines on the lap surface. There were long plastic ribs on the penetration plate fracture, but not on the non-penetration plate fracture. The fatigue resistance stresses in the crack initiation area of the penetration and non-penetration plates calculated based on the mean fatigue limits are 408 MPa and 326 MPa, respectively, which can be used as reference stress for the fatigue design of the laser welded structures. The main reason for the difference in fatigue performance between the two laser welded joints was that the asymmetrical heating in the non-penetration plate thickness resulted in higher residual stress near the welding fusion line.

scholarly journals Fatigue resistance and failure behavior of penetration and non-penetration laser welded lap joints

2020 ◽  
Author(s):  
Xiangzhong Guo ◽  
Wei Liu ◽  
Xiqing Li ◽  
Haowen Shi ◽  
Zhikun Song
Keyword(s):  
Fatigue Resistance ◽  
High Cycle Fatigue ◽  
Failure Modes ◽  
Plate Thickness ◽  
Lap Joints ◽  
Failure Behavior ◽  
Plate Fracture ◽  
Cold Rolled ◽  
The Mean ◽  
The Difference

Abstract The fatigue resistance and failure behaviour of penetration 1.5 + 0.8-P and non-penetration 0.8 + 1.5-N laser welded lap joints prepared with 0.8 mm and 1.5 mm cold-rolled 301L plates were investigated. The weld beads showed a solidification microstructure of primary ferrite with good thermal cracking resistance, and their hardness was lower than that of the plates. The 1.5 + 0.8-P joint exhibited a better resistance to high-cycle fatigue failure, while the 0.8 + 1.5-N joint showed a higher resistance to low-cycle fracture. The failure modes of 0.8 + 1.5-N and 1.5 + 0.8-P joints were 1.5 mm and 0.8 mm lower lap plate fracture, respectively, and the primary cracks were initiated at welding fusion lines on the lap surface. There were long plastic ribs on the penetration plate fracture, but not on the non-penetration plate fracture. The fatigue resistance stress of the penetration and non-penetration plates in the crack initiation areas calculated based on the mean fatigue limits is 408 MPa and 326 MPa, respectively. The main reason for the difference in fatigue performance between the two laser welded joints was that the asymmetrical heating in the non-penetration plate thickness resulted in higher residual stress near the welding fusion line.

scholarly journals Thermal Fatigue Failure Behavior of Surface/Interface of Plasma Cladding Layer

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 646 ◽  
Author(s):  
Yang Li ◽  
Na Tan ◽  
Guo Jin ◽  
Xiufang Cui ◽  
Qiu Li
Keyword(s):  
Fatigue Resistance ◽  
Thermal Fatigue ◽  
Failure Behavior ◽  
Thermal Fatigue Resistance ◽  
Thermal Fatigue Crack ◽  
Cladding Layer ◽  
Precipitated Phase ◽  
Plasma Cladding ◽  
Element Simulation ◽  
The Difference

Co-based coating was prepared by plasma cladding on FV520B substrates. Microstructure of the coatings was observed by scanning electron microscope. Finite element simulation as a predictive method to research the stress distributed after thermal cycling. Thermal fatigue resistance of the coating-substrate was evaluated at temperature of 600 °C, 700 °C, 800 °C, and 900 °C. Results indicate that the surface/interface structure has excellent thermal fatigue resistance at 600 °C, and the thermal fatigue crack initiated near the interface and extended along the grain boundary. The difference of expansion coefficient of the coating and substrate is small near 600 °C, and the difference increased when the temperature climbed above 600 °C. The diffuse elements could be found near the interface after the thermal cycle, and the dislocations and precipitated phase were observed.

scholarly journals Compression Shear Properties of Bonded–Bolted Hybrid Single-Lap Joints of C/C Composites at High Temperature

2020 ◽  
Vol 10 (3) ◽  
pp. 1054
Author(s):  
Yanfeng Zhang ◽  
Zhengong Zhou ◽  
Zhiyong Tan
Keyword(s):  
High Temperature ◽  
Failure Modes ◽  
Shear Failure ◽  
Shear Loading ◽  
Lap Joints ◽  
Failure Behavior ◽  
Displacement Curve ◽  
Analysis Model ◽  
Single Lap Joints ◽  
Hybrid Joints

Based on previous research, in this paper, the compressive shear failure behavior and mechanical properties of bonded–bolted hybrid single-lap joints of C/C composites at high temperature were studied. The compression shear test was performed on the joints at 800 °C to obtain the load–displacement curve and failure morphology. The failure modes of joints were observed by digital microscopy and scanning electron microscopy. A numerical analysis model was implemented in finite element code Abaqus/Explicit embedded with the user material subroutine (VUMAT). The numerical results were compared with the test results to verify the correctness of the model. The interrelationship of the compression shear loading mechanism and the variations in stress distribution between bonded joints and bonded–bolted hybrid joints at high temperature were explored. The progressive damage of hybrid joints and the variations in the ratio of the bolt load to the total load with displacement were obtained.

scholarly journals Experimental Study on the Difference of Shale Mechanical Properties

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Qi Liu ◽  
Bing Liang ◽  
Weiji Sun ◽  
Hang Zhao
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Failure Modes ◽  
High Stress ◽  
Poisson's Ratio ◽  
Bedding Angle ◽  
The Difference

This paper studies the anisotropic characteristics of shale and the difference in mechanical performance between deep shale and outcrop shale. The outcrop shale was collected from the Shuanghe section in Changning County, southern Sichuan, and the deep shale was collected from the Wells Yi201 and Lu202. Study their basic mechanical parameters, failure modes, and wave velocity responses through laboratory tests. Research shows that with the increase of bedding angle, the deformation mode has the trend from elastic deformation to plastic deformation in high-stress state. When the bedding angles are 0°, 30°, and 45°, the weak bedding surface plays a leading role in the formation of the failure surface trend. As the bedding angle increases to 60° and 90°, its influence is weakened. The tensile strength, elastic modulus, and wave velocity decrease with the increase of bedding angle. The compressive strength and Poisson’s ratio have the law of U-type change, there are higher values at 0° and 90°, and the lowest values are at 30°. The brittleness index first increases and then decreases with the increase of the bedding angle. The tensile strength and Poisson’s ratio of outcrop shale and deep shale are close, but the compressive strength of deep shale is only 1/3 of outcrop shale, the elastic modulus is only 3/4 of outcrop shale, and the failure of deep shale is accompanied by instability failure.

UNS A02960

Alloy Digest ◽  
1987 ◽  
Vol 36 (12) ◽  
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
Heat Treating ◽  
Age Hardening ◽  
Casting Alloy ◽  
Passenger Cars ◽  
Temperature Performance ◽  
Mold Casting ◽  
Railway Passenger ◽  
Hardening Heat Treatment

Abstract UNS No. A02060 is an aluminum-mold casting alloy that responds to an age-hardening heat treatment. It is recommended for applications that require a combination of high tensile properties and good machinability. Among its many uses are fuel pump bodies, aircraft fittings and seat frames for railway passenger cars. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on high temperature performance as well as casting, heat treating, machining, and joining. Filing Code: Al-285. Producer or source: Various aluminum companies.

scholarly journals Analytical Investigation of Tension Loaded Deformed Rebar Anchors in Concrete

CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 442-458
Author(s):  
Sandip Chhetri ◽  
Rachel A. Chicchi
Keyword(s):  
Test Data ◽  
Parametric Study ◽  
Failure Modes ◽  
Experimental Testing ◽  
Analytical Investigation ◽  
Failure Behavior ◽  
Capacity Design ◽  
Simulation Results

Experimental testing of deformed rebar anchors (DRAs) has not been performed extensively, so there is limited test data to understand their failure behavior. This study aims to expand upon these limited tests and understand the behavior of these anchors, when loaded in tension. Analytical benchmark models were created using available test data and a parametric study of deformed rebar anchors was performed. Anchor diameter, spacing, embedment, and number of anchors were varied for a total of 49 concrete breakout simulations. The different failure modes of anchors were predicted analytically, which showed that concrete breakout failure is prominent in the DRA groups. The predicted concrete breakout values were consistent with mean and 5% fractile concrete capacities determined from the ACI concrete capacity design (CCD) method. The 5% fractile factor determined empirically from the simulation results was kc = 26. This value corresponds closely with kc = 24 specified in ACI 318-19 and ACI 349-13 for cast-in place anchors. The analysis results show that the ACI CCD formula can be conservatively used to design DRAs loaded in tension by applying a kc factor no greater than 26.

scholarly journals Effect of load sequence interaction on bond-wire lifetime due to power cycling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zoubir Khatir ◽  
Son-Ha Tran ◽  
Ali Ibrahim ◽  
Richard Lallemand ◽  
Nicolas Degrenne
Keyword(s):  
High Stress ◽  
Bipolar Transistors ◽  
Junction Temperature ◽  
Experimental Investigations ◽  
Power Cycling ◽  
Power Modules ◽  
Bond Wire ◽  
Load Sequence ◽  
The Difference ◽  
Heating Duration

AbstractExperimental investigations on the effects of load sequence on degradations of bond-wire contacts of Insulated Gate Bipolar Transistors power modules are reported in this paper. Both the junction temperature swing ($$\Delta T_{j}$$ Δ T j ) and the heating duration ($$t_{ON}$$ t ON ) are investigated. First, power cycling tests with single conditions (in $$\Delta T_{j}$$ Δ T j and $$t_{ON}$$ t ON ), are performed in order to serve as test references. Then, combined power cycling tests with two-level stress conditions have been done sequentially. These tests are carried-out in the two sequences: low stress/high stress (LH) and high stress/low stress (HL) for both $$\Delta T_{j}$$ Δ T j and $$t_{ON}$$ t ON . The tests conducted show that a sequencing in $$\Delta T_{j}$$ Δ T j regardless of the direction “high-low” or “low–high” leads to an acceleration of degradations and so, to shorter lifetimes. This is more pronounced when the difference between the stress levels is large. With regard to the heating duration ($$t_{ON}$$ t ON ), the effect seems insignificant. However, it is necessary to confirm the effect of this last parameter by additional tests.

Fuzzy risk assessment for electro-optical target tracker

2016 ◽  
Vol 33 (6) ◽  
pp. 830-851 ◽  
Author(s):  
Soumen Kumar Roy ◽  
A K Sarkar ◽  
Biswajit Mahanty
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Linear Equations ◽  
Mode Analysis ◽  
Failure Behavior ◽  
Membership Functions ◽  
Design And Development ◽  
Effect Analysis ◽  
Content Type ◽  
Criticality Analysis

Purpose – The purpose of this paper is to evolve a guideline for scientists and development engineers to the failure behavior of electro-optical target tracker system (EOTTS) using fuzzy methodology leading to success of short-range homing guided missile (SRHGM) in which this critical subsystems is exploited. Design/methodology/approach – Technology index (TI) and fuzzy failure mode effect analysis (FMEA) are used to build an integrated framework to facilitate the system technology assessment and failure modes. Failure mode analysis is carried out for the system using data gathered from technical experts involved in design and realization of the EOTTS. In order to circumvent the limitations of the traditional failure mode effects and criticality analysis (FMECA), fuzzy FMCEA is adopted for the prioritization of the risks. FMEA parameters – severity, occurrence and detection are fuzzifed with suitable membership functions. These membership functions are used to define failure modes. Open source linear programming solver is used to solve linear equations. Findings – It is found that EOTTS has the highest TI among the major technologies used in the SRHGM. Fuzzy risk priority numbers (FRPN) for all important failure modes of the EOTTS are calculated and the failure modes are ranked to arrive at important monitoring points during design and development of the weapon system. Originality/value – This paper integrates the use of TI, fuzzy logic and experts’ database with FMEA toward assisting the scientists and engineers while conducting failure mode and effect analysis to prioritize failures toward taking corrective measure during the design and development of EOTTS.

scholarly journals Cyclic fatigue resistance of 2Shape, Twisted File and EndoSequence Xpress nickel-titanium rotary files at intracanal temperature

2018 ◽  
Vol 12 (4) ◽  
pp. 283-287 ◽  
Author(s):  
Gülşah Uslu ◽  
Taha Özyürek ◽  
Mustafa Gündoğar ◽  
Koray Yılmaz
Keyword(s):  
Fatigue Resistance ◽  
Statistical Significance ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Bonferroni Correction ◽  
Significant Difference ◽  
Inner Diameter ◽  
The Difference ◽  
Number Of Cycles ◽  
Analyze Data

Background. The aim of this study was to compare the cyclic fatigue resistance of 2Shape, Twisted File (TF) and EndoSequence Xpress (ESX) nickel-titanium rotary files at intracanal temperature (35°C). Methods. Twenty 2Shape TS1 (25/.04), 20 TF (25/.04) and 20 ESX (25/.04) files were tested for cyclic fatigue at intracanal temperature (35°C). All the instruments were rotated in artificial canals which were made of stainless steel with an inner diameter of 1.5 mm, 60° angle of curvature and a radius curvature of 5 mm until fracture occurred; the time to fracture was recorded in seconds using a digital chronometer and the number of cycles to fracture (NCF) for each file was calculated. Kruskal-Wallis test with Bonferroni correction was performed to statistically analyze data using SPSS 21.0. Statistical significance was set at P<0.05. Results. NCF values revealed that the 2Shape had significantly the highest cyclic fatigue resistance, followed by TF and ESX at intracanal temperature (P<0.05). The difference was significant between the TF and ESX groups (P<0.05). There was no significant difference among the 2Shape, TF and ESX files with respect to the lengths of the fractured file fragments (P>.05). Conclusion. Within the limitations of present study, it was concluded that the cyclic fatigue resistance of 2Shape files at the intracanal temperature is higher than that of TF and ESX files.

A Mathematical Model for Competing Failure Modes in Strain Cycle Fatigue

2006 ◽  
Vol 129 (2) ◽  
pp. 293-303 ◽  
Author(s):  
Gerald T. Cashman
Keyword(s):  
Failure Modes ◽  
High Stress ◽  
Local Strain ◽  
Initiation Site ◽  
Weakest Link ◽  
Strain Relationship ◽  
Powder Metallurgy Alloy ◽  
Link Model ◽  
Cyclic Plastic Strain ◽  
Selection Of

Elevated temperature data for powder metallurgy alloy René 95 generated in vacuum are presented to demonstrate that the life differences observed between surface and internally initiated failures are due to an environmental effect. The transition in behavior from a mode at low stress dominated by internal initiations to a surface dominated mode at high stress is quantitatively described in terms of both a weakest-link model and a local strain relationship. A fatigue failure mechanism is provided that explains that the natural selection of initiation site is based upon the concept that the site displaying the highest local cyclic plastic strain is the location where fatigue initiates.

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