Temperature-Dependent Dwell-Fatigue Behavior of Nanosilver Sintered Lap Shear Joint

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Yansong Tan ◽  
Xin Li ◽  
Yunhui Mei ◽  
Gang Chen ◽  
Xu Chen
Keyword(s):  
Shear Stress ◽  
Dwell Time ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Maximum Shear Stress ◽  
Fatigue Tests ◽  
Shear Strain Rate ◽  
Lap Shear ◽  
Shear Joint ◽  
Dwell Fatigue

A series of dwell-fatigue tests were conducted on nanosilver sintered lap shear joint at elevated temperatures from 125 °C to 325 °C. The effects of temperature and loading conditions on dwell-fatigue behavior of nanosilver sintered lap shear joint were systematically studied. With higher temperature and longer dwell time, creep played a more important part in dwell-fatigue tests. Creep strain accumulated during maximum shear stress hold was found partly recovered by the subsequent cyclic unloading. Both the fracture mode and silver particle growth pattern were characterized by X-ray tomography system and scanning electron microscope (SEM). The mean shear strain rate γ˙m synthesized the effects of various factors, such as temperature, shear stress amplitude, mean shear stress, and dwell time, by which the fatigue and dwell-fatigue life of nanosilver sintered lap shear joint could be well predicted within a factor of two.

scholarly journals Influence of Shot Peening on the Isothermal Fatigue Behavior of the Gamma Titanium Aluminide Ti-48Al-2Cr-2Nb at 750 °C

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1083
Author(s):  
Christoph Breuner ◽  
Stefan Guth ◽  
Elias Gall ◽  
Radosław Swadźba ◽  
Jens Gibmeier ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Shot Peening ◽  
Elevated Temperatures ◽  
Stress Amplitude ◽  
Negative Impact ◽  
Fatigue Behavior ◽  
Surface Hardness ◽  
Fatigue Tests ◽  
Positive Effects ◽  
Isothermal Fatigue

One possibility to improve the fatigue life and strength of metallic materials is shot peening. However, at elevated temperatures, the induced residual stresses may relax. To investigate the influence of shot peening on high-temperature fatigue behavior, isothermal fatigue tests were conducted on shot-peened and untreated samples of gamma TiAl 48-2-2 at 750 °C in air. The shot-peened material was characterized using EBSD, microhardness, and residual stress analyses. Shot peening leads to a significant increase in surface hardness and high compressive residual stresses near the surface. Both effects may have a positive influence on lifetime. However, it also leads to surface notches and tensile residual stresses in the bulk material with a negative impact on cyclic lifetime. During fully reversed uniaxial tension-compression fatigue tests (R = −1) at a stress amplitude of 260 MPa, the positive effects dominate, and the fatigue lifetime increases. At a lower stress amplitude of 230 MPa, the negative effect of internal tensile residual stresses dominates, and the lifetime decreases. Shot peening leads to a transition from surface to volume crack initiation if the surface is not damaged by the shots.

Failure Investigation of Tubular Adhesive Dissimilar Joint

2015 ◽  
Vol 786 ◽  
pp. 43-47
Author(s):  
M. Faizi ◽  
W.M. Syafiq ◽  
M. Afendi ◽  
N.G. Chuen ◽  
Abu Bakar Shahriman
Keyword(s):  
Adhesive Joint ◽  
Failure Load ◽  
Testing Machine ◽  
Welding Process ◽  
Fatigue Tests ◽  
Failure Investigation ◽  
Lap Shear ◽  
Universal Testing ◽  
Shear Joint ◽  
Materials Used

Automotive industries are looking for new implementation to deliver a good finishing product to their customer. By using adhesive material, joining against two steel can replace normal technique which is welding process. However, the strength produced by this method must be investigated. The failure investigation of ductile adhesive intended for use in automotive tubular frame chassis has been assessed using simple tubular lap shear joint. There are two different overlap lengths of tubular adhesive joint considered in this test, i.e., 15 mm and 45 mm. The materials used for the adherents were stainless steel and mild steel, while adhesive used in the experiments was Araldite Standard 90 minutes epoxy resin. Tensile test by utilizing universal testing machine (UTM) was carried out to determine the shear strength of the adhesive joint in different overlap length. Fatigue tests were also conducted. From the results it is found that longer overlap length of the adhesive is preferable for use in automotive tubular frame chassis due to higher failure load it can withstand and better fatigue life.

Surface Topography Influences on the Fatigue Behavior of Composite Joints

2019 ◽  
Vol 809 ◽  
pp. 341-346 ◽  
Author(s):  
Torsten Thäsler ◽  
Jens Holtmannspötter ◽  
Hans Joachim Gudladt
Keyword(s):  
Bond Strength ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Surface Condition ◽  
Atmospheric Pressure Plasma ◽  
Fatigue Tests ◽  
Stress Concentrations ◽  
Release Agent ◽  
Structured Surfaces ◽  
Lap Shear

The surface condition of carbon fibre reinforced plastic (CFRP) substrates is decisive to obtain high bond strength and lifetime of adhesively bonded parts. Those surfaces were adjusted in terms of their microscopic topography by means of peel plies and release foils. The subsequent surface treatment via atmospheric pressure plasma jet or vacuum blasting allowed the modification of the microscopic roughness as well as the surface chemistry. Those configuration were assessed using surface analytic methods as well as quasi-static and cyclic fracture tests on single lap shear specimens. The microscopic surface roughness, if at all, only showed a small influence on the bond strength. Despite release agent residues, fracture was found within the fiber-matrix interface, which caused difficulties in evaluating the effect of surface pretreatments on the adhesion strength. Fatigue tests revealed a lifetime reduction of uneven microscopic rough surfaces, which was assigned to stress concentrations at the tip of asperities. The crack propagation was accelerated in case of release agent residues. If surfaces were free of contaminations, no differences between microscopically smooth and slightly structured surfaces were found. Overall, fatigue testing on single lap shear specimens showed an increased sensitivity with regard to the assessment of surface morphology.

scholarly journals Comparison of High-Temperature Compression and Compression-Compression Fatigue Behavior of Magnesium Alloys DieMag422 and AE42

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 497 ◽  
Author(s):  
Mirko Teschke ◽  
Alexander Koch ◽  
Frank Walther
Keyword(s):  
Magnesium Alloys ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Weight Ratio ◽  
High Strength ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Compression Tests ◽  
Computed Tomographic ◽  
Tensile Fatigue

Due to their high strength-to-weight-ratio, magnesium alloys are very attractive for use in automotive engineering. For application at elevated temperatures, the alloys must be creep-resistant. Therefore, the influence of the operating temperature on the material properties under quasistatic and cyclic load has to be understood. A previous study investigated tensile-tensile fatigue behavior of the magnesium alloys DieMag422 and AE42 at room temperature (RT). The aim of this study was the comparison of both alloys regarding compression, tensile, and compression-compression fatigue behavior. The quasistatic behavior was determined by means of tensile and compression tests, and the tensile-compression asymmetry was analyzed. In temperature increase fatigue tests (TIFT) and constant amplitude tests (CAT), the temperature influence on the cyclic creeping (ratcheting) behavior was investigated, and mechanisms-relevant test temperatures were determined. Furthermore, characteristic fracture mechanisms were evaluated with investigations of the microstructure and the fracture surfaces. The initial material was analyzed in computed tomographic scans and energy dispersive X-ray (EDX) analyses.

Effect of Mean Stress on 2A12-T4 Aluminum Alloy under Tension-Torsion Constant Amplitude Loading

2016 ◽  
Vol 713 ◽  
pp. 334-337
Author(s):  
Tian Qing Liu ◽  
Xin Hong Shi ◽  
Jian Yu Zhang
Keyword(s):  
Shear Stress ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Phase Angle ◽  
Stress Amplitude ◽  
Maximum Shear Stress ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Normal Mean ◽  
Fracture Appearance

Fatigue tests have been carried out to investigate the effects of mean-stress and phase-difference on the tension-torsion fatigue failure of 2A12-T4 aluminum alloy. The results show that for fully reversed tension-torsion loading, the fatigue life increases with the increase of phase angle, but the fatigue life decreases with the increase of phase angle, when mean-stress exists, both for shear mean-stress and normal mean-stress. Fracture appearance shows that the crack initiation is on the direction of maximum shear stress amplitude plane. Critical plane criteria based on the linear combination of the maximum shear stress amplitude and maximum normal stress are studied and further discussion on the drawbacks of this kind of criteria are performed.

Fatigue Behavior of a 22Cr-20Ni-18Co-Fe Alloy at Elevated Temperatures

1994 ◽  
Vol 116 (1) ◽  
pp. 54-61 ◽  
Author(s):  
T. H. Krukemyer ◽  
A. Fatemi ◽  
R. W. Swindeman
Keyword(s):  
Experimental Investigation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Frequency Separation ◽  
Isothermal Fatigue ◽  
Deformation Properties ◽  
Fatigue Data ◽  
Haynes Alloy

An experimental investigation was conducted on Haynes Alloy 556 to study the fatigue behavior of the material at elevated temperatures. Fatigue tests were run at constant temperatures ranging from room temperature to 871°C with strain ranges from 0.265 to 1.5 percent resulting in lives between 102 and 106 cycles. Cyclic deformation properties were evaluated based on the fatigue data. Three fatigue life models were evaluated for their ability to predict the isothermal fatigue lives of the material. These included the Ostergren, Frequency Separation and Stress-Strain-Time models. Strengths and weaknesses of each model are discussed based on the experimental results.

Effect of pulsating tension-torsion combined loading on fatigue behavior in wood

Holzforschung ◽  
2004 ◽  
Vol 58 (6) ◽  
pp. 666-672 ◽  
Author(s):  
Yasutoshi Sasaki ◽  
Mariko Yamasaki
Keyword(s):  
Shear Stress ◽  
Stress State ◽  
Failure Mode ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Combined Loading ◽  
Combined Stress ◽  
Fatigue Process ◽  
Stress Levels ◽  
Time Of Failure

Abstract The effect of cyclic tension-torsion combined loading on the fatigue behavior and stress-strain properties of wood (Japanese cypress) was investigated experimentally. The specimen used in the experiments was a rectangular bar with its major axis in the fiber (longitudinal) direction of wood. Pulsating tension and torsion loadings were respectively applied along and around the longitudinal axis of the specimen. According to the relationships between stress and strain obtained using fatigue tests, the secant modulus of the stress-strain curve changed with an increase in the number of loading cycles, and the differences between the curves for tension and shear were observed. The obtained results of fatigue tests were found to be influenced by the combined stress ratios and the applied stress levels. Bordering on the combined stress state of TB, where tensile and shear stress components were almost equally applied, the trend toward lower stiffness retention was different between tension and shear, and the tensile or torsion failure mode became dominant in the failure mode. The TB state was recognized as a boundary state for both of the stiffness retention and the failure mode. The stiffness retention in the TB state showed a tendency similar to that in the stress state where torsion was dominant regardless of the stress level. On the other hand, the failure mode tended to be tension failure at higher stress levels. Thus, at higher stress levels in the TB state, the effect of the tensile or shear stress component on the fatigue behavior of wood was different between “during the fatigue process” and “the time of failure”. In addition, torsion was dominant for both during the fatigue process and the time of failure at lower stress levels.

scholarly journals The study of the maximum shear stress of the composition of pyrophyllite - clay component – water at elevated temperatures

2019 ◽  
pp. 55-57
Author(s):  
V. Z. Abdrakhimov
Keyword(s):  
Shear Stress ◽  
Water Analysis ◽  
Elevated Temperatures ◽  
Maximum Shear Stress ◽  
Sharp Decrease ◽  
Hot Forming ◽  
Special Importance ◽  
Ultimate Shear Stress ◽  
Clay Component ◽  
Drying Properties

A sharp decrease in the ultimate shear stress in the range of 20‒80 °C is observed when obtaining samples from the clay component without descendents. This contributes to the appearance of cracks and defects in the samples. The use of pyrophyllite in ceramic masses in obtaining samples ensures a gradual decrease in the ultimate shear stress Pm in the range of 20‒80 °C. It is shown that to improve the drying properties of the samples, the composition of pyrophyllite ‒ clay ‒ water is more homogeneous than the composition of clay ‒ water. Analysis of the Pm of the samples under the conditions of hot forming showed that it is not so much the dependence Pm = f(t) that takes on special importance, but the dependence Pm = f(W, t), where t ― the temperature; W ― the humidity. Ill. 1. Ref. 8. Tab. 2.

Sign in / Sign up

Export Citation Format

Share Document