scholarly journals Wear Mechanism of Abrasive Gas Jet Erosion on a Rock and the Effect of Abrasive Hardness on It

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Yong Liu ◽  
Huidong Zhang ◽  
Pathegama Gamage Ranjith ◽  
Jianping Wei ◽  
Xiaotian Liu
Keyword(s):  
Plastic Deformation ◽  
Fatigue Failure ◽  
Failure Modes ◽  
Gas Jet ◽  
Abrasive Particles ◽  
Erosion Models ◽  
Different Types ◽  
Field Geometry ◽  
Abrasive Hardness ◽  
Wear Tests

The existing erosion models of abrasive gas jet tend to neglect the effects of the rebounding abrasive. To address this shortcoming, abrasive wear tests were conducted on limestone by using an abrasive gas jet containing different types of particles and with different standoff distances. The results indicate that erosion pits have the shape of an inverted cone and a hemispherical bottom. An annular platform above the hemispherical bottom connects the bottom with the side of the pit. The primary cause of the peculiar pit shape is the flow field geometry of the gas jet with its entrained particles. There is an annular region between the axis and boundary of the abrasive gas jet, and it contains no abrasive. Particles swirling around the axis form a hemispherical bottom. After rebounding, the abrasive with the highest velocity enlarges the diameters of both the hemispherical bottom and erosion pit and induces the formation of an annular platform. The surface features of different areas of the erosion pit are characterized using a scanning electron microscope (SEM). It can be concluded that the failure modes for different locations are different. The failure is caused by an impact stress wave of the incident abrasive at the bottom. Plastic deformation is the primary failure mode induced by rebounding particles at the sides of the hemispherical bottom. The plastic deformation induced by the incident abrasive and fatigue failure induced by the rebounding abrasive are the primary failure modes on the annular platform. Fatigue failure induced by rebounding particles is the primary mode at the sides of the erosion pits. The rock failure mechanism that occurs for particles with different hardness is the same, but the rock damaged by the hard abrasive has a rougher surface.

scholarly journals Evaluation of Wear Behaviour in Metallic Binders Employed in Diamond Tools for Cutting Stone

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3988
Author(s):  
Fátima Ternero ◽  
Pedro M. Amaral ◽  
Jorge Cruz Fernandes ◽  
Luís Guerra Rosa
Keyword(s):  
Wear Behavior ◽  
Wear Behaviour ◽  
Empirical Expression ◽  
Testing Conditions ◽  
Diamond Tools ◽  
Test Methodology ◽  
Different Types ◽  
Stone Material ◽  
The Difference ◽  
Wear Tests

A type of disc-on-plate test methodology was used to determine the wear behavior of metallic binders employed in the manufacturing of diamond impregnated tools. The disc consists of a special circular wheel that allows the binder materials alone (i.e., without diamond, but sintered under conditions identical to those of the complete tool) to be tested against a plate of stone material under pre-determined testing conditions. The testing conditions are intended to be equivalent to those used in the industrial processes. Using plates of five types of granite and one type of marble, this work comprises wear tests of 15 different types of metallic binders and two sintering modes conducted under, at least, three different values of contact-force. The analysis of the results demonstrated that the wear of the binders can be related to their mechanical properties through an empirical expression. The larger the difference between the characteristics of the tribological pair (binder versus stone), the higher is the correlation between the experimental wear data and the values given by the empirical expression. The relationships presented in this work allow predicting the wear behavior of the binder, and therefore may help in the design process of diamond tools. There was a clear difference between the wear behavior of metallic binders when they were employed against the two main classes of stone under analysis (marble and granite).

Fatigue Failure Modes in Self-Piercing Riveted Aluminium Alloy Joints

Volume 3 ◽  
2004 ◽  
Author(s):  
L. Han ◽  
K. Young ◽  
R. Hewitt ◽  
A. Chrysanthou ◽  
J. M. O’Sullivan
Keyword(s):  
Aluminium Alloy ◽  
Fatigue Failure ◽  
Failure Modes ◽  
Surface Condition ◽  
Fatigue Behaviour ◽  
Alloy Sheet ◽  
Static Tests ◽  
Failure Patterns ◽  
Interfacial Conditions ◽  
Sheet Surface

Self-piercing riveting, as an alternative joining method to spot-welding, has attracted considerable interest from the automotive industry and has been widely used in aluminium intensive vehicles. One of the important factors that need to be considered is the effect of cyclic loading in service, leading to possible fatigue failure. The previous work reported in the public domain on the behaviour of self-piercing rivets has mainly focused on static tests. The work which is reported in this paper is concerned with the fatigue behaviour of single-rivet joints, joining two 2mm 5754 aluminium alloy sheets. The investigation also examined the effect of interfacial conditions on the fatigue behaviour. A number of fatigue failure mechanisms were observed based on rivet fracture, sheet fracture and combinations of these. The investigation has shown that they were dependent on the applied load and the sheet surface condition. Three-parameter Weibull analysis, using Reliasoft Weibull ++5.0 software, was conducted to analyse the experimental results. The analysis enabled the prediction of early-type failure (infant mortality failure) and wear-out failure patterns depending on the condition of the self-piercing riveted joints and the alloy sheet surface.

scholarly journals Investigation of creep and fatigue in high temperature polymer matrix composites using a micromechanical approach

2021 ◽  
Author(s):  
Alireza Sayyidmousavi
Keyword(s):  
High Temperature ◽  
Fatigue Failure ◽  
Polymer Matrix ◽  
Failure Criterion ◽  
Failure Modes ◽  
Polymer Matrix Composites ◽  
Matrix Composites ◽  
Difficult Situation ◽  
Strain Evolution ◽  
Micromechanical Approach

Polymer matrix composites (PMC’s) are widely used in critical aerospace structures due to their numerous advantageous mechanical properties. Recently, PMC’s have been considered for high temperature applications where viscoelasticity arising from the time dependent nature of the polymer matrix becomes an important consideration. This inherent viscoelasticity can significantly influence deformation, strength and failure response of these materials under different loading modes and environmental factors. With a potentially large number of plies of different fiber directions and perhaps material properties, determining a fatigue failure criterion of any degree of generality through experiments only, may seem to be an unrealistic task. This difficult situation may be mitigated through the development of suitable theoretical micro or macro mechanical models that are founded on considering the fatigue failure of the constituting laminas. The micro‐approach provides a detailed examination of the individual failure modes in each of the constituent materials i.e. fiber, matrix. In this work, a micromechanical approach is used to study the role of viscoelasticity on the fatigue behavior of polymer matrix composites. In particular, the study examines the interaction of fatigue and creep in polymer matrix composites. The matrix phase is modeled as a vicoelastic material using Schapery’s single integral constitutive equation. Taking viscoelsticity into account allows the study of creep strain evolution during the fatigue loading. The fatigue failure criterion is expressed in terms of the fatigue failure functions of the constituent materials. The micromechanical model is also used to calculate these fatigue failure functions from the knowledge of the S‐N diagrams of the composite material in longitudinal, transverse and shear loadings thus eliminating the need for any further experimentation. Unlike the previous works, the present study can distinguish between the strain evolution due to fatigue and creep. The results can clearly show the contribution made by the effect of viscoelasticity to the total strain evolution during the fatigue life of the specimen. Although the effect of viscoelsticity is found to increase with temperature, its contribution to strain development during fatigue is compromised by the shorter life of the specimen when compared to lower temperatures.

Creep and Relaxation of Oxygen-Free Copper

1943 ◽  
Vol 10 (2) ◽  
pp. A101-A105
Author(s):  
Evan A. Davis
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Different Types

Abstract This paper contains results of creep and relaxation tests on an oxygen-free copper at temperatures up to 235 C. The effect of the stress and the temperature upon the strain rate has been noted and an effort has been made to correlate the results of the two different types of tests by using various theories of plastic deformation.

Impact of multi-dimensional vibration trajectories on quality and failure modes in ultrasonic bonding

2019 ◽  
Vol 2019 (1) ◽  
pp. 000509-000514
Author(s):  
Reinhard Schemmel ◽  
Florian Eacock ◽  
Collin Dymel ◽  
Tobias Hemsel ◽  
Matthias Hunstig ◽  
...  
Keyword(s):  
Cross Sections ◽  
Failure Modes ◽  
Copper Substrate ◽  
Industrial Process ◽  
Acoustic Microscopy ◽  
Ultrasonic Power ◽  
Bond Quality ◽  
Ultrasonic Bonding ◽  
Different Types ◽  
Electrical Connections

Abstract Ultrasonic joining is a common industrial process. To build electrical connections in the electronics industry, uni-axial and torsional ultrasonic vibration have been used to join different types of workpieces for decades. Many influencing factors like ultrasonic power, bond normal force, bond duration and frequency are known to have a high impact on bond quality and reliability. Multi-dimensional bonding has been investigated in the past to increase ultrasonic power and consequently bond strength. This contribution is focused on the comparison of circular, multi-frequency planar and uniaxial vibration trajectories used for ultrasonic bonding of copper pins on copper substrate. Bond quality was analyzed by shear tests, scanning acoustic microscopy and interface cross-sections.

Bearing Capacity Analysis on Slotted End Plate Connection Joints of Different Types

2012 ◽  
Vol 166-169 ◽  
pp. 764-769
Author(s):  
Ruo Hui Qiang ◽  
Ming Zhou Su ◽  
Junfen Yang ◽  
Jinbo Cui
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Great Influence ◽  
Mechanical Behaviors ◽  
End Plate ◽  
Different Types ◽  
Plastic Stage ◽  
Plate Connection ◽  
Force Displacement ◽  
Main Factor

Four different types of full-scale slotted end plate (SEP) connection joints are tested to determine their failure modes and damage mechanisms under ultimate loading. Researches on mechanical behaviors of I-type, T-type, U-type and Groove SEP connection joints bearing compression are studied, which also analyze their force-displacement behaviors and developing processes of deformation and strain. The results show that the bearing capacities of I, grooved, T and U types SEP connections are increased gradually, which indicate the SEP’s type has great influence on the ultimate strength of joints. The instability of SEP is the main factor to cause the loss of bearing capacity of the connection, which is shown through the development of strain, that SEP enters into plastic stage and the other regions still are elastic.

Risk Based Acceptance Criteria for Joints Subject to Fatigue Deterioration

2004 ◽  
Vol 127 (2) ◽  
pp. 150-157 ◽  
Author(s):  
Daniel Straub ◽  
Michael Havbro Faber
Keyword(s):  
Fatigue Failure ◽  
System Reliability ◽  
Failure Modes ◽  
Optimal Allocation ◽  
Influence Factor ◽  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Revealed Preferences ◽  
Acceptance Criteria ◽  
The Individual

Different approaches to determine the acceptance criteria for fatigue induced failure of structural systems and components are discussed and compared. The considered approaches take basis in either optimization (societal cost-benefit analysis) or are derived from past and actual practice or codes (revealed preferences). The system acceptance criteria are expressed in terms of the maximal acceptable annual probability of collapse due to fatigue failure. Acceptance criteria for the individual fatigue failure modes are then derived using a simplified system reliability model. The consequence of fatigue failure of the individual joints is related to the overall system by evaluating the change in system reliability given fatigue failure. This is facilitated by the use of a simple indicator, the Residual Influence Factor. The acceptance criteria is thus formulated as a function of the system redundancy and complexity. In addition, the effect of dependencies in the structure on the acceptance criteria are investigated. Finally an example is presented where the optimal allocation of the risk to different welded joints in a jacket structure is performed by consideration of the necessary maintenance efforts.

Oscillating Contact Wear in Cold Sprayed Ti6Al4V Coatings for Aeronautical Repairs

2018 ◽  
Vol 941 ◽  
pp. 1686-1691 ◽  
Author(s):  
Pedro Poza ◽  
Paloma Sirvent ◽  
Álvaro Rico ◽  
Claudio J. Múnez ◽  
Miguel Ángel Garrido
Keyword(s):  
Plastic Deformation ◽  
Room Temperature ◽  
Point Of View ◽  
Wear Behaviour ◽  
Bulk Alloy ◽  
Contact Wear ◽  
Heat Treated ◽  
Mixed Layers ◽  
Wear Tests ◽  
Mixed Mechanism

Ti6Al4V coatings were cold sprayed onto the same bulk alloy using standard conditions and a set of parameters developed to improve the coating’s performance. In addition, the enhanced coating was heat treated to improve coating adhesion and reduce porosity. Wear tests were performed, onto the coatings and the substrate, in oscillating conditions, which simulate wear induced by the contact with bearing parts during vibration. Wear behaviour at room temperature is dominated by a mixed mechanism, which involves plastic deformation and transference from the counterbody forming mechanically mixed layers. As temperature is increased, the formation of mechanically mixed layers dominates wear. The wear resistance of the enhanced coatings is similar to the bulk alloy, or even better in some conditions. Consequently, cold sprayed improved coatings could be used for repairing titanium components from the contact wear point of view.

Study on the effect of length–short side ratio on the fatigue performance of the rib girder bridge's carriageway slab

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tianlai Yu ◽  
Linlin Zhang ◽  
Zizheng Liu
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Failure ◽  
Fatigue Resistance ◽  
Failure Modes ◽  
Group Structure ◽  
Load Level ◽  
Fatigue Performance ◽  
Short Side ◽  
Content Type ◽  
Side Ratio

PurposeThe fatigue problems of the carriageway slabs of reinforced concrete rib-beam bridges were studied. The analysis of the carriageway slabs could not achieve the actual stress state.Design/methodology/approachBased on this characteristic, the reinforced concrete T-beam group structure system was taken as the research object. Four scale models of the carriageway slabs of reinforced concrete ribbed bridges were designed. The fatigue failure modes and actual fatigue resistance of the carriageway slabs with different length-to-side ratios were systematically studied through static load and fatigue experiments. Based on this, the concrete damage plasticity model (CDP model) was combined with numerical simulation analysis to study the influence of the length-to-short-side ratio of the carriageway slab on the fatigue performance and the remaining bearing capacity.FindingsThe results show that the fatigue failure of the carriageway slab is a three-stage failure; the ratio of the long and short sides has a significant effect on the fatigue performance of the carriageway slab. Under the same fatigue load level, the smaller the ratio of the long and short sides of the carriageway slab.Originality/valueThe fatigue resistance of the unidirectional board is significantly lower than that of the bidirectional board. It is recommended to use the bidirectional board in actual engineering design.

scholarly journals Experimental Study on Hysteretic Behavior of the Overlapped K-Joints with Concrete Filled in Chord

2019 ◽  
Vol 9 (7) ◽  
pp. 1456 ◽  
Author(s):  
Wenwei Yang ◽  
Ruhao Yan ◽  
Yaqi Suo ◽  
Guoqing Zhang ◽  
Bo Huang
Keyword(s):  
Plastic Deformation ◽  
Energy Dissipation ◽  
Cyclic Loading ◽  
Bearing Capacity ◽  
Failure Modes ◽  
The United States ◽  
Hysteretic Behavior ◽  
Tensile Failure ◽  
Element Analysis ◽  
Better Than

Due to the insufficient radial stiffness of the steel tube, the cracking of the weld and the plastic deformation of the string often occur under the cyclic loading of the hollow section pipe joint. In order to avoid such a failure, the overlapped K-joints were strengthened by pouring different concrete into the chords. Furthermore, to explore the detailed effect of filling different concrete in a chord on the hysteretic behavior of the overlapped K-joints, six full-scale specimens were fabricated by two forms, which included the circular chord and braces, the square chord and circular braces, and the low cyclic loading tests, which were carried out. The failure modes, hysteretic curves and skeleton curves of the joints were obtained, and the bearing capacity, ductility and energy dissipation of the joints were evaluated quantitatively. The results showed that plastic failure occurs on the surface of the chord of the joints without filling concrete, while the failure mode of the joints filled with concrete in the chords was the tensile failure of the chords at the weld of the brace toe, and the compressive braces had a certain buckling deformation; The strengthening measures of concrete filled with chord can effectively improve the mechanical properties of the K-joints, the delay of the plastic deformation of the chord, and improve the bearing capacity of the K-joints. Contrarily, the ductility coefficient and the energy dissipation ratio of K-joints decreased with the concrete filled in the chord. The hysteretic behavior of the K-joints with a circular chord and brace was slightly better than that of the K-joints with a square chord and circular brace, and the hysteretic behavior of the K-joints strengthened with fly ash concrete, which was better than that of the K-joints strengthened with ordinary concrete. The results of ANSYS (a large general finite element analysis software developed by ANSYS Company in the United States) analysis agreed well with the experimental results.

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