A.E. Johnson, V.D. Mathur and J. Henderson
This work was undertaken to examine the possibility of predicting the creep deflexion of magnesium alloy struts from tensile creep data. Creep deflexion tests on magnesium alloy…
Abstract
This work was undertaken to examine the possibility of predicting the creep deflexion of magnesium alloy struts from tensile creep data. Creep deflexion tests on magnesium alloy struts at room temperature, under four loads, and lasting 1,000 hours, have been made and interpreted by the use of tensile creep test data for the same magnesium alloy. For strut deflexions small compared with length, and such that plane sections of the strut remain plane, it appears that the following assumptions arc reasonable: (i) during bending and compression creep of the strut similar relations exist between the stress, time and creep strain, as under conditions of simple tensile or compressive creep; and (ii) the rate of creep in any fibre of the strut is a function only of the current stress and time and not of the path by which the current conditions arc reached. These assumptions appear to lead to an average error in computed values of deflexion of an order which for practical purposes is small. It seems reasonably possible that the above mentioned assumptions may be expected to hold for struts of heat resistant material at elevated temperatures such as are met with in practice, provided that the order of deflexion is analogous to that occurring in the current tests, and the creep characteristics of the material are of a generally similar nature.
THE work of Johnson, Mathur and Henderson on the ‘Creep Deflexion of Magnesium Alloy Struts’ raised the question in the present writer's mind of the stress distribution in the…
Abstract
THE work of Johnson, Mathur and Henderson on the ‘Creep Deflexion of Magnesium Alloy Struts’ raised the question in the present writer's mind of the stress distribution in the beam cross‐section, and the variation of this distribution with time. The precise computation of the stress distribution in an eccentrically loaded strut appears to be a very difficult problem, and the present note is concerned with the much simpler case of a beam subjected to a constant bending moment.
A.E. Johnson, J. Henderson and V.D. Mathur
The nature of the relation between complex stress creep under conditions of relaxation and complex stress creep under conditions of steady stress was investigated. The required…
Abstract
The nature of the relation between complex stress creep under conditions of relaxation and complex stress creep under conditions of steady stress was investigated. The required relation has been examined for an RR59 aluminium alloy at 200 deg. C. and for a magnesium (2 per cent aluminium) alloy at 50 deg. C. For RR59 aluminium alloy at 200 deg. C. and for magnesium (2 per cent aluminium) alloy at 50 deg. C., a reasonably close prediction of the course of relaxation complex stress time curves is given by the mechanical age hardening theory of creep on the basis of steady complex stress creep data. Other mechanical theories tend to predict for a specific relaxed stress a relaxation time in excess of that noted in experiment.
A.E. Johnson, J. Henderson and V.D. Mathur
As stated in general terms in a previous paragraph, in the ease of this material the following complex stress relaxation tests were made: two pure torsion tests from initial…
Abstract
As stated in general terms in a previous paragraph, in the ease of this material the following complex stress relaxation tests were made: two pure torsion tests from initial stresses of 4 tons/sq. in. and 3 tons/sq. in.; two tests having a stress ratio T/S=0·4 and having initial stress values of T=1·6, S=4 and T=1·2, S=3 tons/sq. in. in the two cases; two tests having a stress ratio T/S=0·8 and having initial stress values T=3·2, S=4 and T=2·62, S=3·28 tons/sq. in. respectively; and finally one test having a stress ratio T/S=1·5 and having an initial stress value T=4·5 and S=3 tons/sq. in. (i.e. a total of seven tests).
A.E. Johnson, J. Henderson and Y.D. Mathur
The purpose of the investigation was to examine the tertiary creep and the creep fracture characteristics of an aluminium alloy to specification B.S.2L42, subject to complex…
Abstract
The purpose of the investigation was to examine the tertiary creep and the creep fracture characteristics of an aluminium alloy to specification B.S.2L42, subject to complex stressing at 200 dog. C. The scope of the work involved seven pure torsion, pure tension, and combined tension and torsion creep tests, of durations between 300 hrs. and 3,000 hrs., on the aluminium alloy at 200 deg. C., and analysis of the results.
Presents a review on implementing finite element methods on supercomputers, workstations and PCs and gives main trends in hardware and software developments. An appendix included…
Abstract
Presents a review on implementing finite element methods on supercomputers, workstations and PCs and gives main trends in hardware and software developments. An appendix included at the end of the paper presents a bibliography on the subjects retrospectively to 1985 and approximately 1,100 references are listed.
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Benny Barak, Anil Mathur, Yong Zhang, Keun Lee and Emmanuel Erondu
Field survey studies undertaken in Nigeria, Korea, China and India explored the way inner‐age satisfaction is experienced in those culturally diverse societies. Chronologically 20…
Abstract
Field survey studies undertaken in Nigeria, Korea, China and India explored the way inner‐age satisfaction is experienced in those culturally diverse societies. Chronologically 20 to 59 year old respondents’ inner‐age satisfaction was gauged as the average difference between feel, look, do, and interest cognitive (self‐perceived) and desired (ideal) inner‐age dimensions. Analyses of covariance (with chronological age factored out) across the four nations showed Nigeria to differ significantly in terms of inner‐age satisfaction from each Asian population, contrary to the Asian societies where no differences were found across samples (except between Korea and India where inner‐age satisfaction differed at a p .05). High levels of satisfaction with inner‐age (coming about when cognitive and desired ages are equal) commonly transpired: 31.4 per cent of Indian, 36.9 per cent of Nigerian, 44.3 per cent of Chinese, and 44.9 per cent of Korean respondents. Age dissatisfaction in an elder direction (ideal age older than self‐perceived age) was atypical and happened most often among Nigerian (23.4 per cent) and least among Korean subjects (10.7 per cent). In contrast, wishing for a younger innerage was a commonplace phenomenon in India (50.6 per cent of the sample), as well as in China where it occurred the least (36.6 per cent). The study’s findings imply the universal nature of the way human beings (irrespective of culture) perceive and feel about inner‐age, as well as the potential of an inner‐age satisfaction psychographic as a relevant consumer behavior segmentation trait for marketing planners of age‐sensitive products and services who seek to standardize their global branding and distribution.
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Ajay Vadakkepatt, Sanjay R. Mathur and Jayathi Y. Murthy
Topology optimization is a method used for developing optimized geometric designs by distributing material pixels in a given design space that maximizes a chosen quantity of…
Abstract
Purpose
Topology optimization is a method used for developing optimized geometric designs by distributing material pixels in a given design space that maximizes a chosen quantity of interest (QoI) subject to constraints. The purpose of this study is to develop a problem-agnostic automatic differentiation (AD) framework to compute sensitivities of the QoI required for density distribution-based topology optimization in an unstructured co-located cell-centered finite volume framework. Using this AD framework, the authors develop and demonstrate the topology optimization procedure for multi-dimensional steady-state heat conduction problems.
Design/methodology/approach
Topology optimization is performed using the well-established solid isotropic material with penalization approach. The method of moving asymptotes, a gradient-based optimization algorithm, is used to perform the optimization. The sensitivities of the QoI with respect to design variables, required for optimization algorithm, are computed using a discrete adjoint method with a novel AD library named residual automatic partial differentiator (Rapid).
Findings
Topologies that maximize or minimize relevant quantities of interest in heat conduction applications are presented. The efficacy of the technique is demonstrated using a variety of realistic heat transfer applications in both two and three dimensions, in conjugate heat transfer problems with finite conductivity ratios and in non-rectangular/non-cuboidal domains.
Originality/value
In contrast to most published work which has either used finite element methods or Cartesian finite volume methods for transport applications, the topology optimization procedure is developed in a general unstructured finite volume framework. This permits topology optimization for flow and heat transfer applications in complex design domains such as those encountered in industry. In addition, the Rapid library is designed to provide a problem-agnostic pathway to automatically compute all required derivatives to machine accuracy. This obviates the necessity to write new code for finding sensitivities when new physics are added or new cost functions are considered and permits general-purpose implementations of topology optimization for complex industrial applications.
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Martin Götz and Ernest H. O’Boyle
The overall goal of science is to build a valid and reliable body of knowledge about the functioning of the world and how applying that knowledge can change it. As personnel and…
Abstract
The overall goal of science is to build a valid and reliable body of knowledge about the functioning of the world and how applying that knowledge can change it. As personnel and human resources management researchers, we aim to contribute to the respective bodies of knowledge to provide both employers and employees with a workable foundation to help with those problems they are confronted with. However, what research on research has consistently demonstrated is that the scientific endeavor possesses existential issues including a substantial lack of (a) solid theory, (b) replicability, (c) reproducibility, (d) proper and generalizable samples, (e) sufficient quality control (i.e., peer review), (f) robust and trustworthy statistical results, (g) availability of research, and (h) sufficient practical implications. In this chapter, we first sing a song of sorrow regarding the current state of the social sciences in general and personnel and human resources management specifically. Then, we investigate potential grievances that might have led to it (i.e., questionable research practices, misplaced incentives), only to end with a verse of hope by outlining an avenue for betterment (i.e., open science and policy changes at multiple levels).