Continuum Models for the Mechanical Response of Paper and Paper Composites: Past, Present, and Future

1990 ◽  
Vol 197 ◽  
Author(s):  
Jeffrey C. Suhling
Keyword(s):  
Mechanical Response ◽  
Constitutive Relations ◽  
Paper Industry ◽  
Theoretical Models ◽  
Material Behavior ◽  
Continuum Models ◽  
Future Research ◽  
Fiber Network ◽  
Structural Configurations ◽  
Paper Composites

ABSTRACTPaper and paper composites are utilized in applications where they are subjected to multiaxial stress states and changing environmental conditions. Such materials exhibit nonlinear anisotropic material behavior which is time dependent and affected adversely by slight changes in moisture content and temperature. At present, lack of adequate theoretical models often hampers the design and development of structurally optimized paper products. Therefore, it has been common practice in the pulp and paper industry to use trial and error, and empirical approaches. Accurate continuum models for the mechanical behavior of paper and paper composites are needed to guide the paper product design process.In this work, a limited review of the existing methods for modeling the mechanical response of paper and paper composites is given. At first, a brief overview of the goals of current modeling techniques based on hydrogen bond, fiber network, and continuum approaches is presented. The governing equations and capabilities of current continuum models are then discussed in greater detail. Theories which include linear elastic (generalized Hooke's Law), nonlinear elastic (hyperelastic), linear viscoelastic, nonlinear viscoelastic, and inelastic constitutive relations are addressed. Finally, applications of existing continuum theories to the analysis of paper materials in structural configurations are presented. After these discussions, the limitations of the available continuum models are assessed and future research needs are suggested.

The Rheology of Frozen Soils

2007 ◽  
Vol 17 (1) ◽  
pp. 12147-1-12147-14 ◽  
Author(s):  
Lukas U. Arenson ◽  
Sarah M. Springman ◽  
Dave C. Sego
Keyword(s):  
Mechanical Response ◽  
Soil Mechanics ◽  
Rheological Behaviour ◽  
Theoretical Models ◽  
Complex Stress ◽  
Frozen Soil ◽  
Future Research ◽  
Frozen Soils ◽  
Current State ◽  
Number Of Factors

Abstract The rheological behaviour of frozen soils depends on a number of factors and is complex. Stress and temperature histories as well as the actual composition of the frozen soil are only some aspects that have to be considered when analysing the mechanical response. Recent improvements in measuring methods for laboratory investigations as well as new theoretical models have assisted in developing an improved understanding of the thermo-mechanical processes at play within frozen soils and representation of their response to a range of perturbations. This review summarises earlier work and the current state of knowledge in the field of frozen soil research. Further, it presents basic concepts as well as current research gaps. Suggestions for future research in the field of frozen soil mechanics are also made. The goal of the review is to heighten awareness of the complexity of processes interacting within frozen soils and the need to understand this complexity when developing models for representing this behaviour.

The Social Neuroscience of Cooperation

2018 ◽  
Author(s):  
Jay Joseph Van Bavel
Keyword(s):  
Theoretical Models ◽  
Brain Regions ◽  
Review Literature ◽  
Social Neuroscience ◽  
Future Research ◽  
A Value ◽  
Group Cooperation ◽  
Neural Processes ◽  
The Social ◽  
Cooperative Decision Making

We review literature from several fields to describe common experimental tasks used to measure human cooperation as well as the theoretical models that have been used to characterize cooperative decision-making, as well as brain regions implicated in cooperation. Building on work in neuroeconomics, we suggest a value-based account may provide the most powerful understanding the psychology and neuroscience of group cooperation. We also review the role of individual differences and social context in shaping the mental processes that underlie cooperation and consider gaps in the literature and potential directions for future research on the social neuroscience of cooperation. We suggest that this multi-level approach provides a more comprehensive understanding of the mental and neural processes that underlie the decision to cooperate with others.

Cancer and Cancer Treatment-Related Cognitive Impairment

2019 ◽  
pp. 60-83
Author(s):  
James C.  Root ◽  
Elizabeth Ryan ◽  
Tim A. Ahles
Keyword(s):  
Cancer Survivors ◽  
Cancer Treatment ◽  
Clinical Presentation ◽  
Functional Neuroimaging ◽  
Theoretical Models ◽  
Future Research ◽  
Cognitive Changes ◽  
Central Nervous System Cancer ◽  
Pharmacologic Treatments

As the population of cancer survivors has grown into the millions, there is increasing emphasis on understanding how late effects of treatment impact survivors’ ability return to work/school, ability to function and live independently, and overall quality of life. Cognitive changes are one of the most feared problems among cancer survivors. This chapter describes the growing literature examining cognitive changes associated with non-central nervous system cancer and cancer treatment. Typical elements of cancer treatment are discussed, followed by a description of clinical presentation, self-reported and objectively assessed cognitive findings, and results of structural and functional neuroimaging research. Genetic and other risk factors for cognitive decline following treatment are identified and discussed, together with biomarkers and animal models of treatment-related effects. This is followed by a discussion of behavioral and pharmacologic treatments. Finally, challenges and recommendations for future research are provided to help guide subsequent research and theoretical models.

Emerging Syndromes

2017 ◽  
Author(s):  
Kelly C. Allison ◽  
Jennifer D. Lundgren
Keyword(s):  
Empirical Studies ◽  
Theoretical Models ◽  
Future Research ◽  
Night Eating Syndrome ◽  
Statistical Manual ◽  
Night Eating ◽  
Diagnostic And Statistical Manual ◽  
Impairment In Functioning ◽  
Atypical Anorexia Nervosa ◽  
Comorbid Psychopathology

The Diagnostic and Statistical Manual, fifth edition, of the American Psychiatric Association (2013) has designated several disorders under the diagnosis of otherwise specified feeding and eating disorder (OSFED). This chapter evaluates three of these, night eating syndrome (NES), purging disorder (PD), and atypical anorexia nervosa (atypical AN). It also reviews orthorexia nervosa, which has been discussed in the clinical realm as well as the popular press. The history and definition for each is reviewed, relevant theoretical models are presented and compared, and evidence for the usefulness of the models is described. Empirical studies examining the disorders’ independence from other disorders, comorbid psychopathology, and, when available, medical comorbidities, are discussed. Distress and impairment in functioning seem comparable between at least three of these emerging disorders and threshold eating disorders. Finally, remaining questions for future research are summarized.

THE INFLUENCE OF SOCIAL TIES AND SELF-EFFICACY IN FORMING ENTREPRENEURIAL INTENTIONS AND MOTIVATING NASCENT BEHAVIOR

2007 ◽  
Vol 12 (03) ◽  
pp. 275-293 ◽  
Author(s):  
JENNIFER SEQUEIRA ◽  
STEPHEN L. MUELLER ◽  
JEFFREY E. MCGEE
Keyword(s):  
Self Efficacy ◽  
Strong Predictor ◽  
Theoretical Models ◽  
Entrepreneurial Intentions ◽  
Future Research ◽  
Personal Network ◽  
Network Ties ◽  
Strong Ties ◽  
Business Knowledge ◽  
Entrepreneurial Action

Theoretical models of entrepreneurship suggest that an individual's intention to start an enterprise is a strong predictor of eventual entrepreneurial action. Less understood are factors that influence the likelihood of entrepreneurial intentions and nascent behavior. In this study, we develop and test several hypotheses about how social network ties and self-efficacy affect entrepreneurial intentions and nascent behavior. We found that a personal network of supportive strong ties coupled with high entrepreneurial self-efficacy increases the likelihood of entrepreneurial intentions and nascent behavior. A personal network of weak ties with practical business knowledge and experience also increases the likelihood of entrepreneurial nascent behavior but not entrepreneurial intentions. In contrast, a personal network of strong ties with practical business knowledge and experience has little effect on either intentions or nascent behavior and may, in fact, suppress both. The contribution of this study to nascent entrepreneurship research and implications for future research are discussed.

Atomistic Aspects of Fracture Modelling in the Framework of Continuum Mechanics

1998 ◽  
Vol 538 ◽  
Author(s):  
F. Cleri
Keyword(s):  
Continuum Mechanics ◽  
Constitutive Relations ◽  
Point Of View ◽  
Atomic Scale ◽  
Continuum Models ◽  
Cohesive Law ◽  
Macroscopic Models ◽  
Scale Models ◽  
Level Information ◽  
Set Up

AbstractThe validity and predictive capability of continuum models of fracture rests on basic informations whose origin lies at the atomic scale. Examples of such crucial informations are, e.g., the explicit form of the cohesive law in the Barenblatt model and the shear-displacement relation in the Rice-Peierls-Nabarro model. Modem approaches to incorporate atomic-level information into fracture modelling require to increase the size of atomic-scale models up to millions of atoms and more; or to connect directly atomistic and macroscopic, e.g. finite-elements, models; or to pass information from atomistic to continuum models in the form of constitutive relations. A main drawback of the atomistic methods is the complexity of the simulation results, which can be rather difficult to rationalize in the framework of classical, continuum fracture mechanics. We critically discuss the main issues in the atomistic simulation of fracture problems (and dislocations, to some extent); our objective is to indicate how to set up atomistic simulations which represent well-posed problems also from the point of view of continuum mechanics, so as to ease the connection between atomistic information and macroscopic models of fracture.

Perceived Exertion: An Active or Passive Process?

1985 ◽  
Vol 7 (4) ◽  
pp. 371-378 ◽  
Author(s):  
W. Jack Rejeski
Keyword(s):  
Parallel Processing ◽  
Empirical Study ◽  
Perceived Exertion ◽  
Theoretical Models ◽  
Physical Work ◽  
Future Research ◽  
Work Intensity ◽  
Ratings Of Perceived Exertion ◽  
Subjective Estimates ◽  
Parallel Processing Model

Subjective estimates of physical work intensity are considered of major importance to those concerned with prescription of exercise. This article reviews major theoretical models which might guide research on the antecedents for ratings of perceived exertion (RPE). It is argued that an active rather than passive view of perception is warranted in future research, and a parallel-processing model is emphasized as providing the needed structure for such reconceptualization. Moreover, existing exercise research is reviewed as support for this latter approach and several suggestions are offered with regard to needed empirical study.

Historical Economics and the Minor Prophets

2021 ◽  
pp. 322-340
Author(s):  
Jason M. Silverman
Keyword(s):  
Social Justice ◽  
Economic Models ◽  
Theoretical Models ◽  
Social Structures ◽  
Future Research ◽  
Southern Levant ◽  
Production And Consumption ◽  
Minor Prophets

This essay calls for a thorough reassessment of economics and the Minor Prophets. Since existing economic models based on both Marxism or (Neo-) liberalism are problematic as are many basic economic concepts, new theorizing based on ancient data is necessary. Taking Bourdieu’s “economic field” as a starting frame, this essay considers the material elements of production and consumption in the ancient southern Levant, their patterns and social structures, and some issues in the socioeconomic world of the Minor Prophets. These then raise new questions for sample prophetic passages (Amos, Joel, Haggai, Micah, and Zechariah). The essay points to some issues these considerations raise for analyzing the famous calls for social justice, and it closes by pointing in some potential directions for improved theoretical models in future research.

Uncertainty Quantification in Predicting Behaviour of Rubber-Like Materials in Uni-Axial Loading

2020 ◽  
Author(s):  
Aref Ghaderi ◽  
Vahid Morovati ◽  
Pouyan Nasiri ◽  
Roozbeh Dargazany
Keyword(s):  
Uncertainty Quantification ◽  
Mechanical Response ◽  
Pure Shear ◽  
Constitutive Models ◽  
Material Behavior ◽  
Elastic Behavior ◽  
Deterministic Models ◽  
Data Set ◽  
Material Parameters ◽  
Axial Extension

Abstract Material parameters related to deterministic models can have different values due to variation of experiments outcome. From a mathematical point of view, probabilistic modeling can improve this problem. It means that material parameters of constitutive models can be characterized as random variables with a probability distribution. To this end, we propose a constitutive models of rubber-like materials based on uncertainty quantification (UQ) approach. UQ reduces uncertainties in both computational and real-world applications. Constitutive models in elastomers play a crucial role in both science and industry due to their unique hyper-elastic behavior under different loading conditions (uni-axial extension, biaxial, or pure shear). Here our goal is to model the uncertainty in constitutive models of elastomers, and accordingly, identify sensitive parameters that we highly contribute to model uncertainty and error. Modern UQ models can be implemented to use the physics of the problem compared to black-box machine learning approaches that uses data only. In this research, we propagate uncertainty through the model, characterize sensitivity of material behavior to show the importance of each parameter for uncertainty reduction. To this end, we utilized Bayesian rules to develop a model considering uncertainty in the mechanical response of elastomers. As an important assumption, we believe that our measurements are around the model prediction, but it is contaminated by Gaussian noise. We can make the noise by maximizing the posterior. The uni-axial extension experimental data set is used to calibrate the model and propagate uncertainty in this research.

scholarly journals Simulation of Cyclic Loading on Pipe Elbows Using Advanced Plane-Stress Elastoplasticity Models1

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Konstantinos Chatziioannou ◽  
Yuner Huang ◽  
Spyros A. Karamanos
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Mechanical Response ◽  
Low Cycle Fatigue ◽  
Constitutive Relations ◽  
Cyclic Plasticity ◽  
Integration Scheme ◽  
Repeated Loading ◽  
Finite Element Software ◽  
Hardening Models

Abstract This work investigates the response of industrial steel pipe elbows subjected to severe cyclic loading (e.g., seismic or shutdown/startup conditions), associated with the development of significant inelastic strain amplitudes of alternate sign, which may lead to low-cycle fatigue. To model this response, three cyclic-plasticity hardening models are employed for the numerical analysis of large-scale experiments on elbows reported elsewhere. The constitutive relations of the material model follow the context of von Mises cyclic elasto-plasticity, and the hardening models are implemented in a user subroutine, developed by the authors, which employs a robust numerical integration scheme, and is inserted in a general-purpose finite element software. The three hardening models are evaluated in terms of their ability to predict the strain range at critical locations, and in particular, strain accumulation over the load cycles, a phenomenon called “ratcheting.” The overall good comparison between numerical and experimental results demonstrates that the proposed numerical methodology can be used for simulating accurately the mechanical response of pipe elbows under severe inelastic repeated loading. Finally, this paper highlights some limitations of conventional hardening rules in simulating multi-axial material ratcheting.

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