scholarly journals Mechanical Stresses Induced by Compression in Castings of the Load-carrying Grate

2016 ◽  
Vol 16 (2) ◽  
pp. 51-54
Author(s):  
J. Słowik ◽  
A. Drotlew ◽  
B. Piekarski
Keyword(s):  
Heat Treatment ◽  
Stress Distribution ◽  
Stress Level ◽  
Stress Transfer ◽  
State Of Stress ◽  
Structure Changes ◽  
Load Carrying ◽  
The Relationship ◽  
Forced Movement

Abstract The main aim of this study was to examine the compression-induced state of stress arising in castings of the guide grates during operation in pusher-type furnaces for heat treatment. The effect of grate compression is caused by its forced movement in the furnace. The introduction of flexible segments to the grate structure changes in a significant way the stress distribution, mainly by decreasing its value, and consequently considerably extends the lifetime of the grates. The stress distribution was examined in the grates with flexible segments arranged crosswise (normal to the direction of the grate compression) and lengthwise (following the direction of force). A regression equation was derived to describe the relationship between the stress level in a row of ribs in the grate and the number of flexible segments of a lengthwise orientation placed in this row. It was found that, regardless of the distribution of the flexible segments in a row, the stress values were similar in all the ribs included in this row, and in a given row of the ribs/flexible segments a similar state of stress prevailed, irrespective of the position of this row in the whole structure of the grate and of the number of the ribs/flexible segments introduced therein. Parts of the grate responsible for the stress transfer were indicated and also parts which play the role of an element bonding the structure.

A Study of the Fracture Process at the FRP-Masonry Interface: The Role of the Periodic Pattern of Bricks and Mortar Joints

2014 ◽  
Vol 624 ◽  
pp. 611-618 ◽  
Author(s):  
Francesco Focacci ◽  
Christian Carloni
Keyword(s):  
Axial Strain ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Effective Length ◽  
Periodic Pattern ◽  
Frp Composites ◽  
Load Response ◽  
Reinforced Polymer ◽  
Load Carrying

This paper sheds light into the effect of the periodic pattern of bricks and mortar joints on the load-carrying capacity of the interface between fiber-reinforced polymer (FRP) composites and masonry. Two simplified cohesive material laws are proposed for the FRP-mortar and FRP-brick interfaces, which allow for the computation in closed form of a finite effective bond length Leff of the interfaces. The aforementioned simplified interfacial laws are employed to compute the load response of the FRP-masonry interface, and to obtain the interfacial shear stress, the FRP axial strain, and the slip profiles along the bonded length. The results indicate that length of the stress-transfer zone (LSTZ) of the FRP-masonry interface varies periodically as its location shifts with respect to the position of the mortar joints. Furthermore LSTZ can be different from the effective length of the FRP-brick interface and is influenced by the size of the bricks and mortar joints.

Filament Fragmentation Phenomena

1989 ◽  
Vol 170 ◽  
Author(s):  
Juan C. Figueroa ◽  
Linda S. Schadler ◽  
Campbell Laird
Keyword(s):  
Strain Energy ◽  
Stress Transfer ◽  
Fiber Surface ◽  
Yield Information ◽  
The Matrix ◽  
Two Parameters ◽  
The Relationship

AbstractThe effect of fiber surface treatments on the relationship between the tensile strength of a filament and the shear strength of its interphase is one of the central issues facing composite materials technologists today. We demonstrate here that analysis of fragmentation phenomena in monofilament composites can simultaneously yield information about these two parameters. Characterization of shear stress transfer zones in non-critical fragments has led us to the determination of interphase strength.A phenomenological treatment that highlights the role of the matrix in the fragmentation process is presented here. This analysis considers issues such as the strain energy exchange between a failing fiber and the matrix, as well as interphase relaxation due to the viscoelastic nature of the matrix. Our observations of the fragmentation phenomena in AU4/polycarbonate monofilament composites indicate that the fiber/matrix interaction in this system is governed by micromechanical locking.

scholarly journals Role of nanoparticles in achieving macroscale superlubricity of graphene/nano-SiO2 particle composites

Friction ◽  
2021 ◽  
Author(s):  
Panpan Li ◽  
Li Ji ◽  
Hongxuan Li ◽  
Lei Chen ◽  
Xiaohong Liu ◽  
...  
Keyword(s):  
Shear Force ◽  
Applied Load ◽  
Carbon Film ◽  
Material System ◽  
Simple Material ◽  
Friction Process ◽  
Load Carrying ◽  
Graphene Nanoscrolls ◽  
The Relationship

AbstractRecent studies have reported that adding nanoparticles to graphene enables macroscale superlubricity to be achieved. This study focuses on the role of nanoparticles in achieving superlubricity. First, because graphene nanoscrolls can be formed with nanoparticles as seeds under shear force, the applied load (or shear force) is adjusted to manipulate the formation of graphene nanoscrolls and to reveal the relationship between graphene-nanoscroll formation and superlubricating performance. Second, the load-carrying role of spherical nano-SiO2 particles during the friction process is verified by comparison with an elaborately designed fullerene that possesses a hollow-structured graphene nanoscroll. Results indicate that the incorporated nano-SiO2 particles have two roles in promoting the formation of graphene nanoscrolls and exhibiting load-carrying capacity to support macroscale forces for achieving macroscale superlubricity. Finally, macroscale superlubricity (friction coefficient: 0.006–0.008) can be achieved under a properly tuned applied load (2.0 N) using a simple material system in which a graphene/nano-SiO2 particle composite coating slides against a steel counterpart ball without a decorated diamond-like carbon film. The approach described in this study could be of significance in engineering.

Structure changes of high-strength economically alloyed steel 09KhGN2MD (09CrMnNi2MoCu) when tempering

2019 ◽  
pp. 15-26 ◽  
Author(s):  
M. V. Golubeva ◽  
O. V. Sych ◽  
E. I. Khlusova ◽  
G. D. Motovilina ◽  
E. V. Sviatysheva ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fracture Mode ◽  
High Strength ◽  
Resistant Steel ◽  
Optimal Heat ◽  
Optimal Heat Treatment ◽  
Structure Changes ◽  
The Relationship ◽  
Quenching And Tempering

Purpose of the present investigation is to determine the optimal heat treatment parameters that ensure yield strength over 690 MPa in combination with toughness of at least 35 J/cm2at temperature –70°C in new economically alloyed cold-resistant steel. The effect of various quenching and tempering parameters on mechanical properties, structure of steel and fracture mode of samples after impact tests at temperature –70°C has been studied. The relationship between the properties, structure and fracture mode of steel samples is shown. The optimal heat treatment parameters of new economically alloyed cold-resistant steel are determined.

The role of particle shape on the stress distribution in a sandpile

2007 ◽  
Vol 464 (2089) ◽  
pp. 99-116 ◽  
Author(s):  
I Zuriguel ◽  
T Mullin
Keyword(s):  
Experimental Investigation ◽  
Stress Distribution ◽  
Particle Shape ◽  
Local Minimum ◽  
Mechanical Stability ◽  
Stress Profile ◽  
Anisotropic Particles ◽  
Primary Stress ◽  
The Relationship

The results of an experimental investigation into the counter-intuitive phenomenon that a local minimum in the normal stress profile is sometimes found under the apex of a sandpile are presented. Specifically, the effects of particle shape on the stress distribution are studied and it is shown that anisotropy of the particles significantly enhances the dip. This amplification is attributed to the mechanical stability induced by boundary alignment of the anisotropic particles. Circular, ellipsoidal and pear-shaped cylinders are used and the stress propagates principally towards the sides of the pile through primary stress chains. Secondary chains are also present and we propose that the relationship between the magnitudes of the ratio of primary to secondary chains is correlated with the size of the dip.

scholarly journals The Influence of Heat Treatment Parameters on the Cracks Growth under Cyclic Bending in St-Ti Clad Obtained by Explosive Welding

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 338 ◽  
Author(s):  
Dariusz Rozumek ◽  
Grzegorz Kwiatkowski
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Explosive Welding ◽  
Annealing Temperature ◽  
Rectangular Cross Section ◽  
Fatigue Cracks ◽  
Micro Hardness ◽  
Cyclic Bending ◽  
Structure Changes ◽  
The Relationship

The current work focuses on the effect of time and temperature of annealing on the change in the structure and cracks growth and fatigue life of the steel-titanium bimetal obtained by explosive welding. Cyclic bending tests were performed for different levels of annealing temperature on bimetal specimens of a rectangular cross-section. The fatigue crack growth was measured by microscopy. Structure changes of steel, titanium and bond area resulted in a different micro-hardness distribution. The relationship between the level of the annealing temperature, the propagation of fatigue cracks, structure changes and micro-hardness level is analyzed. The heat treatment of the bimetal at the temperature of 500 °C does not result in considerable changes in the structure of steel and titanium. The diffusion of carbon to titanium was observed. A higher annealing temperature results in a lower fatigue life. Also, for a given annealing temperature, a longer annealing time results in a higher fatigue life.

Choosing a Markov blanket

2020 ◽  
Vol 43 ◽  
Author(s):  
Thomas Parr
Keyword(s):  
Markov Blanket ◽  
Target Article ◽  
The Relationship

Abstract This commentary focuses upon the relationship between two themes in the target article: the ways in which a Markov blanket may be defined and the role of precision and salience in mediating the interactions between what is internal and external to a system. These each rest upon the different perspectives we might take while “choosing” a Markov blanket.

Strain-induced martensite effects on transgranular carbide precipitation in type 304 stainless steels

1991 ◽  
Vol 49 ◽  
pp. 604-605
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D. Matlock
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Deformation Twin ◽  
Austenitic Stainless Steels ◽  
Carbide Precipitation ◽  
Strain Induced Martensite ◽  
Type 304

Thermomechanically induced strain is a key variable producing accelerated carbide precipitation, sensitization and stress corrosion cracking in austenitic stainless steels (SS). Recent work has indicated that higher levels of strain (above 20%) also produce transgranular (TG) carbide precipitation and corrosion simultaneous with the grain boundary phenomenon in 316 SS. Transgranular precipitates were noted to form primarily on deformation twin-fault planes and their intersections in 316 SS.Briant has indicated that TG precipitation in 316 SS is significantly different from 304 SS due to the formation of strain-induced martensite on 304 SS, though an understanding of the role of martensite on the process has not been developed. This study is concerned with evaluating the effects of strain and strain-induced martensite on TG carbide precipitation in 304 SS. The study was performed on samples of a 0.051%C-304 SS deformed to 33% followed by heat treatment at 670°C for 1 h.

Staring Down Death

Crisis ◽  
2016 ◽  
Vol 37 (3) ◽  
pp. 212-217 ◽  
Author(s):  
Thomas E. Joiner ◽  
Melanie A. Hom ◽  
Megan L. Rogers ◽  
Carol Chu ◽  
Ian H. Stanley ◽  
...  
Keyword(s):  
Suicide Risk ◽  
Clinical Utility ◽  
Blink Rate ◽  
Specific Task ◽  
Careful Planning ◽  
Eye Blink ◽  
Eye Blinks ◽  
Potential Clinical Utility ◽  
The Relationship

Abstract. Background: Lowered eye blink rate may be a clinically useful indicator of acute, imminent, and severe suicide risk. Diminished eye blink rates are often seen among individuals engaged in heightened concentration on a specific task that requires careful planning and attention. Indeed, overcoming one’s biological instinct for survival through suicide necessitates premeditation and concentration; thus, a diminished eye blink rate may signal imminent suicidality. Aims: This article aims to spur research and clinical inquiry into the role of eye blinks as an indicator of acute suicide risk. Method: Literature relevant to the potential connection between eye blink rate and suicidality was reviewed and synthesized. Results: Anecdotal, cognitive, neurological, and conceptual support for the relationship between decreased blink rate and suicide risk is outlined. Conclusion: Given that eye blinks are a highly observable behavior, the potential clinical utility of using eye blink rate as a marker of suicide risk is immense. Research is warranted to explore the association between eye blink rate and acute suicide risk.

Parenting Behaviors and Anxiety in Young Adults

2015 ◽  
Vol 36 (3) ◽  
pp. 170-176 ◽  
Author(s):  
Erin N. Stevens ◽  
Joseph R. Bardeen ◽  
Kyle W. Murdock
Keyword(s):  
Effortful Control ◽  
Parenting Behaviors ◽  
Protective Role ◽  
Anxiety Symptoms ◽  
Interactive Effects ◽  
Parental Overprotection ◽  
High Control ◽  
Development Of Anxiety ◽  
The Relationship

Parenting behaviors – specifically behaviors characterized by high control, intrusiveness, rejection, and overprotection – and effortful control have each been implicated in the development of anxiety pathology. However, little research has examined the protective role of effortful control in the relation between parenting and anxiety symptoms, specifically among adults. Thus, we sought to explore the unique and interactive effects of parenting and effortful control on anxiety among adults (N = 162). Results suggest that effortful control uniquely contributes to anxiety symptoms above and beyond that of any parenting behavior. Furthermore, effortful control acted as a moderator of the relationship between parental overprotection and anxiety, such that overprotection is associated with anxiety only in individuals with lower levels of effortful control. Implications for potential prevention and intervention efforts which specifically target effortful control are discussed. These findings underscore the importance of considering individual differences in self-regulatory abilities when examining associations between putative early-life risk factors, such as parenting, and anxiety symptoms.

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