scholarly journals Experimental tests of planar strain theory for predicting bone cross-sectional longitudinal and shear strains

2016 ◽  
Vol 219 (19) ◽  
pp. 3082-3090 ◽  
Author(s):  
Kari A. Verner ◽  
Michael Lehner ◽  
Luis P. Lamas ◽  
Russell P. Main
Keyword(s):  
Experimental Tests ◽  
Strain Theory ◽  
Cross Sectional ◽  
Shear Strains ◽  
Planar Strain

Testing the Strain Theory of Suicide – The Moderating Role of Social Support

Crisis ◽  
2020 ◽  
Vol 41 (2) ◽  
pp. 82-88 ◽  
Author(s):  
Bob Lew ◽  
Ksenia Chistopolskaya ◽  
Yanzheng Liu ◽  
Mansor Abu Talib ◽  
Olga Mitina ◽  
...  
Keyword(s):  
Social Support ◽  
Suicidal Behavior ◽  
Online Survey ◽  
Perceived Social Support ◽  
Strain Theory ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Psychological Strains ◽  
Moderating Role

Abstract. Background: According to the strain theory of suicide, strains, resulting from conflicting and competing pressures in an individual's life, are hypothesized to precede suicide. But social support is an important factor that can mitigate strains and lessen their input in suicidal behavior. Aims: This study was designed to assess the moderating role of social support in the relation between strain and suicidality. Methods: A sample of 1,051 employees were recruited in Beijing, the capital of China, through an online survey. Moderation analysis was performed using SPSS PROCESS Macro. Social support was measured with the Multidimensional Scale of Perceived Social Support, and strains were assessed with the Psychological Strains Scale. Results: Psychological strains are a good predictor of suicidality, and social support, a basic need for each human being, moderates and decreases the effects of psychological strains on suicidality. Limitations: The cross-sectional survey limited the extent to which conclusions about causal relationships can be drawn. Furthermore, the results may not be generalized to the whole of China because of its diversity. Conclusion: Social support has a tendency to mitigate the effects of psychological strains on suicidality.

scholarly journals Push and Pull Factors of Transnational Street Begging in South Western Nigeria

2015 ◽  
Vol 13 (2) ◽  
Author(s):  
Usman Adekunle Ojedokun ◽  
Adeyinka Abideen Aderinto
Keyword(s):  
Data Collection ◽  
Federal Government ◽  
Strain Theory ◽  
Sampling Techniques ◽  
Survey Questionnaire ◽  
Pull Factors ◽  
Cross Sectional ◽  
Push And Pull Factors ◽  
Depth Interview ◽  
Push And Pull

Street begging in Nigeria has traditionally been dominated by indigenous beggars. However, a growing trend in the phenomenon in recent times is the involvement of migrant beggars in streets. Against this background, this paper examined the push and pull factors of transnational street begging in South Western Nigeria. The study was exploratory and cross-sectional in design. Anomie-strain theory was adopted as conceptual framework. Convenience and purposive sampling techniques were employed to select 395 respondents. Survey questionnaire and in-depth interview were the methods of data collection. Transnational street beggars attributed their involvement in street begging to different socio-economic and environmental challenges in their home-countries. Most of them (53.4%) migrated to Nigeria for better opportunity. The Federal Government of Nigeria is urged to put in place a mechanism through which refugees who are genuinely in need can be helped and/or distinguished from migrants who have permanently taken to street begging as their means of livelihood.

scholarly journals Stiffness of Concrete-Filled Thin-Walled Steel Tubular Slender Columns

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Alireza Bahrami ◽  
Ali Mahmoudi Kouhi
Keyword(s):  
Uniform Distribution ◽  
Experimental Tests ◽  
Simulation Method ◽  
Steel Tube ◽  
Initial Stiffness ◽  
Cross Sectional ◽  
Circular Column ◽  
Finite Element Software ◽  
Thin Walled ◽  
Slender Columns

Abstract Concrete-filled thin-walled steel tubular slender columns are studied in this paper to evaluate their stiffness. The slender columns have various steel tube thicknesses, length/diameter (width) ratios, and concrete compressive strengths. The columns are loaded by axial and eccentric loads. Two experimental tests of the slender and stub columns are described. Also, the finite element software ABAQUS is utilised to simulate and analyse the columns. The tested columns are simulated taking into account all their features in the tests to verify the simulation of the columns. The simulation results are compared with the tests results which reveal that good agreements exist between them. Thus, the proposed simulation method of the columns is verified. In order to assess the stiffness of the columns under different conditions, various load eccentricities (0 mm, 25 mm, and 50 mm), cross-sectional configurations (circular, rectangular, and square), and steel tube thicknesses (2 mm, 3.35 mm, and 5 mm) are adopted for the developed columns. The columns are simulated and analysed based on the verified simulation method considering the mentioned conditions. As a conclusion, the stiffness of the columns is generally reduced by the increase of the load eccentricity from 0 mm to 25 mm and 50 mm. Further, more uniform distribution of the stiffness is witnessed for the columns with lower eccentricities. In addition, the enhancement of the load eccentricity increased the reduction slope of the stiffness graph for the columns. Although the initial stiffness of the circular column is slightly lower than the rectangular and square columns, the stiffness has more uniform distribution which is preferred. Larger stiffness is achieved for the columns by increasing the steel tube thickness from 2 mm to 3.35 mm and 5 mm.

Punching shear behaviour of flat slabs with different reinforcement schemes: openings and rectangularity effects

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Donia Salman ◽  
Rabab Allouzi ◽  
Nasim Shatarat
Keyword(s):  
Structural Engineering ◽  
Experimental Tests ◽  
Shear Capacity ◽  
Punching Shear ◽  
Shear Behaviour ◽  
Cross Sectional ◽  
Content Type ◽  
Flat Slabs ◽  
Reinforced Concrete Slabs ◽  
Rectangular Columns

PurposeThe main goal is to investigate the effect of size and location of opening and column size on the punching shear strength. Openings are often needed in order to install mechanical and electrical services. This process takes away part of the concrete volume which is responsible for resisting the shear forces and any unbalanced moment. Furthermore, the application of rectangular columns in flat slabs is commonly used in practice as they provide lateral stiffness to the building. They are also utilised in garages and multi-storey buildings where these elongated cross-sectional columns reduce the effective span length between adjacent columns.Design/methodology/approachThis research is a numerical-based investigation that is calibrated based on a thirteen previously tested and numerically calibrated slab specimens with no openings. A parametric study is conducted in this study to consider the effect of other parameters, which are the size and location of opening and the rectangularity ratio of column in order to evaluate their effect on the punching shear capacity. A total of 156 models are developed to study these factors. Additionally, the predicted shear carrying capacity of the simulated slabs is calculated using the ACI318–19 and Eurocode (EC2-04) equation.FindingsThe presence of openings reduced the punching shear capacity. The small opening's location and orientation have almost no effect except for one slab. For slabs of large openings, the presence of openings reduced the punching capacity. The punching capacity is higher when the openings are farther from the column. The numerically obtained results of slabs with rectangular columns show lower punching capacity compared to slabs of squared columns with the same length of the punching shear control perimeter. The punching capacity for all slabs is predicted by ACI318–19 and Eurocode (EC2-04) and it is found that Eurocode (EC2-04) provided a closer estimation.Originality/valueThe slabs considered for calibration were reinforced with four different punching shear reinforcement configurations, namely; ordinary closed rectangular stirrups, rectangular spiral stirrups, advanced rectangular spiral stirrups and circular spiral. Generally, there has been limited research on concrete flat slabs with openings in comparison with other subjects related to structural engineering (Guan, 2009) and no research on punching shear with openings of slabs reinforced with these reinforcement schemes. The available research focussed on the effects of openings on the flexural behaviour of reinforced concrete slabs includes Casadei et al. (2003), Banu et al. (2012) and Elsayed et al. (2009). In addition, experimental tests that examined slabs supported on rectangular columns are very limited.

CAE Correlation of Sealing Pressure of a Press-in-Place Gasket

2021 ◽  
Keyword(s):  
Internal Pressure ◽  
Pressure Distribution ◽  
Load Condition ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Test Results ◽  
Local Pressure ◽  
Cross Sectional ◽  
Pad Test ◽  
Sealing Pressure

The Press-in-Place (PIP) gasket is a static face seal with self-retaining feature, which is used for the mating surfaces of engine components to maintain the reliability of the closed system under various operating conditions. Its design allows it to provide enough contact pressure to seal the internal fluid as well as prevent mechanical failures. Insufficient sealing pressure will lead to fluid leakage, consequently resulting in engine failures. A test fixture was designed to simulate the clamp load and internal pressure condition on a gasket bolted joint. A Sensor pad using TEKSCAN equipment was used to capture the overall and local pressure distribution of the PIP gasket under various engine loading conditions. Then, the Sensor pad test results were compared with simulated CAE results from computer models. Through the comparisons, it is found that the gasket sealing pressure of test data and CAE data show good correlation for bolt load condition 500N when compared to internal pressure side load condition of 0.138 MPa & 0.276 MPa. Moreover, the gasket cross-sectional pressure distribution obtained by experimental tests and CAE models correlated very well with R2 ranging from 90 to 99% for all load cases. Both CAE and Sensor pad test results shows increase in sealing pressure when internal side pressure is applied to the gasket seal.

MODELLING OF CHANGES IN SURFACE TOPOGRAPHY IN DRY SLIDING CONDITIONS

Tribologia ◽  
2016 ◽  
Vol 267 (3) ◽  
pp. 61-70
Author(s):  
Andrzej DZIERWA ◽  
Rafał REIZER
Keyword(s):  
Numerical Model ◽  
Surface Topography ◽  
Experimental Tests ◽  
Dry Sliding ◽  
Sectional Area ◽  
Cross Sectional ◽  
Analytical Methodology ◽  
Tribological Tests ◽  
The One ◽  
Worn Surface

Metrology of surface topography is presently so developed that, in some ways, we can predict the surface behaviour of the one part in co-operation with another element. We can single out two main approaches to the modelling of surface texture. In the first one, the modelling does not take into account the conditions of the technological or operational formation of the surface, while in the second, more complicated approach, modelling takes into account the real conditions of forming the surface. In this work, tribological tests were carried out in dry sliding conditions, and the analytical methodology of wear or worn surface. Approximations obtained using the second approach are usually worse than those using the first method [L. 8–10]. In the presented work, tribological tests in dry sliding conditions were carried out, and a numerical model to determine the cross-sectional area of wear in presented conditions was produced, and the results obtained using modelling and experimental tests were compared.

A Parametric Study on Interlaminar Shear Strains in Cord-Rubber Composites

1984 ◽  
Vol 57 (1) ◽  
pp. 168-183 ◽  
Author(s):  
J. DeEskinazi ◽  
R. J. Cembrola
Keyword(s):  
Shear Strain ◽  
Relative Motion ◽  
Strong Influence ◽  
Design Parameters ◽  
Cross Sectional ◽  
Design Variables ◽  
Study Results ◽  
Shear Strains ◽  
Interlaminar Shear ◽  
Belt Width

Abstract The effect of different design variables used in the construction of tire belts on the interply shear phenomenon was studied using a simple, belted cylinder structure. Only balanced belt constructions were considered. The finite element method was used in the analysis of the belted structure. Predicted results were verified by performing experiments with selected combinations of the design parameters studied. Predicted and experimental results indicate the presence of interply shear strains in the cross-sectional plane of the belts; however, due to difficulties involved in measuring these strains experimentally, they have not been treated in this study. Results for shear strains in the circumferential planes only have been presented. Results for the interply shear strains at the belt edge indicate that the belt cord angle has a very strong influence on the interply shear phenomenon. It was shown that the shape of the curve depicting the relationship between cord angle and interply shear strains is influenced by other design variables of the belt as well as properties of adjacent plies, such as the bladder used to simulate a radial tire carcass ply. Interply shear strains decrease with increasing thickness between the plies and modulus of the interply rubber. In the case of a stiffer rubber, the reduction in shear strain is entirely due to a reduction in the relative motion between the belts. However, in the case of an increased interply thickness, which is accompanied by an increase in relative motion between the belts, the reduction in shear is the result of the relative motion being distributed over a larger thickness. Increasing the belt cord modulus results in an increase in interply shear strains for relatively low values of the modulus. However, beyond a certain value, approximately the modulus of fiberglass cords, increasing the cord modulus does not significantly affect interply shear strains. The shear strain-belt width relationship is strongly influenced by the cord angle used in the belts. Depending on the value of the latter, the shear strain can be a decreasing function of belt width or remain relatively constant as belt width is varied. The degree of localization of the interply shear phenomenon at the belt edge was also studied. All of the variables considered in this study, with the exception of the cord modulus, seem to affect the distribution of the shear strain along the width of the belt to varying extents. The belt width seems to have a strong influence, with wider belts resulting in significant shear strains confined to the vicinity of the belt edge.

scholarly journals Calibration of a Load Measurement System for an Unmanned Aircraft Composite Wing Based on Fibre Bragg Gratings and Electrical Strain Gauges

Aerospace ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 27 ◽  
Author(s):  
Łukasz Święch
Keyword(s):  
Measurement System ◽  
Complete System ◽  
Experimental Tests ◽  
Unmanned Aircraft ◽  
Strain Gauges ◽  
Fibre Bragg Grating ◽  
Cross Sectional ◽  
Measurement Systems ◽  
Fibre Bragg Gratings ◽  
Composite Wing

This paper presents the issues concerning calibration of a measurement system for monitoring the cross-sectional forces and moments of an unmanned aircraft’s wing. A composite cantilever wing with built-in measurement systems based on electrical resistance and Fibre Bragg Grating strain gauges has been made for the purpose of the study. Measurement systems placed along the span of the wing consist of strain gauges arranged in a manner that allows the monitoring of shear force, bending and twisting moments. The calibration process was described in terms of both experimental tests and mathematical formalism. The calibration results were compared for the complete system, consisting of three sensor units, and for various combinations of separated measuring points. For each case, a reading inaccuracy analysis was carried out and conclusions, including recommendations for the design of this kind of measurement system, were formulated.

Are Black Restaurant Servers Tipped Less Than White Servers? Three Experimental Tests of Server Race Effects on Customers’ Tipping Behaviors

2021 ◽  
pp. 193896552110366
Author(s):  
Zachary W. Brewster ◽  
Kenneth Gourlay ◽  
Gerald Roman Nowak
Keyword(s):  
Causal Effect ◽  
Experimental Tests ◽  
Small Samples ◽  
Future Research ◽  
Cross Sectional ◽  
Large Samples ◽  
Survey Experiments ◽  
Race Effects ◽  
Widespread Phenomenon ◽  
The Relationship

A limited number of published studies have presented evidence indicating that restaurant customers discriminate against Black servers by tipping them less than their White coworkers. However, the cross-sectional, localized, and small samples that were analyzed in these extant studies do not support any unqualified claim that consumer racial discrimination in tipping practices is a widespread phenomenon. Thus, in an effort to further clarify the relationship between restaurant servers’ race and customers’ tipping practices, we present results from three survey experiments designed to assess the causal effect of servers’ race on customers’ tipping intentions. In three independent, demographically diverse, and relatively large samples of U.S. consumers, we found no evidence to conclude that all else being equal consumers discriminate against Black restaurant servers by tipping them less than comparable White servers. Furthermore, the null effects of servers’ race on customers’ tipping practices were not found to be sensitive to variation in service quality, dining satisfaction, servers’ sex, customers’ sex, or customers’ race. Our results challenge the generalizability of the previously observed server race effects on customers’ tipping practices and point toward the need for future research that aims to advance our understanding of the conditions under which customers’ tipping practices are sensitive to the perceived race of their server. The implications of our results for restaurant operations and directions for future research are also discussed.

Fracture Process of Aluminum/Aluminum Nitride Interfaces during Thermal Cycling

2010 ◽  
Vol 638-642 ◽  
pp. 3895-3900 ◽  
Author(s):  
Yoshiyuki Nagatomo ◽  
Ryo Muranaka ◽  
Hiromasa Hayashi ◽  
Yoshirou Kuromitsu ◽  
Noriyuki Kuwano
Keyword(s):  
Thermal Cycling ◽  
Fracture Process ◽  
Bending Test ◽  
Power Devices ◽  
Cross Sectional ◽  
Fine Grained ◽  
Backscattered Electron ◽  
Shear Strains ◽  
Device Operation ◽  
Scanning Electron

Al circuit substrates, which are composed of a sintered AlN plate and pure Al plate joined to both sides of the AlN plate, are used for semiconductor power devices. It is important to prevent fracture of the Al/AlN interface to ensure normal and stable device operation. In this study, the fracture process of Al/AlN interface during thermal cycling was investigated using advanced scanning electron microscopy (SEM). Al circuits joined to an AlN plate were plastically deformed with thermal cycling. Al grains were divided with the formation of sub-boundaries due to the plastic deformation. After 2000 thermal cycles, a crack was generated at edges of the Al/AlN interface and propagated gradually to the center of the substrate. Cross-sectional observation, using an angle selective backscattered electron detector (AsB), revealed that the Al grain size near the Al/AlN interface decreased to 3 m or less, and the crack proceeded along the Al grain boundaries. To clarify the temperature dependence of the fracture process, a repeated bending test was performed at various temperatures. Shear strains were induced at the Al/AlN interface by the repeated bending. The rate of crack propagation tends to be higher at higher temperatures for bending test. In substrates bent at 373 K or higher, the crack proceeded after the Al grains had been refined. These results indicate that fine-grained Al resulting from thermal cycling is formed by creep deformation and recrystallization at higher temperatures. Thus, improving the creep strength of the Al plate is thought to be effective for prevent cracking during thermal cycling. The effect of additive elements in the Al plate was also discussed in this study.

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