scholarly journals Accurate Numerical Solutions for Elastic-Plastic Models

1979 ◽  
Vol 101 (3) ◽  
pp. 226-234 ◽  
Author(s):  
H. L. Schreyer ◽  
R. F. Kulak ◽  
J. M. Kramer
Keyword(s):  
Numerical Solutions ◽  
Constant Strain Rate ◽  
Single Step ◽  
Isotropic Hardening ◽  
Contour Plots ◽  
Integration Algorithms ◽  
The Common ◽  
The Difference ◽  
Von Mises ◽  
Two Parameters

The accuracy of two integration algorithms is studied for the common engineering condition of a von Mises, isotropic hardening model under plane stress. Errors in stress predictions for given total strain increments are expressed with contour plots of two parameters; an angle in the pi-plane and the difference between the exact and computed yield surface radii. The two methods are the tangent predictor-radial return approach and the elastic predictor-radial corrector algorithm originally developed by Mendelson. The accuracy of a combined tangent predictor-radial corrector algorithm is also investigated. For single-step constant-strain-rate increments the elastic predictor-radial corrector method is generally the most accurate, although errors in angle can be significant. The use of a simple subincrementation formula with any one of the three approaches yields results that would be acceptable for most engineering problems.

Fracture of Amorphous Polymers

1967 ◽  
Vol 40 (4) ◽  
pp. 1049-1059 ◽  
Author(s):  
R. F. Landel ◽  
R. F. Fedors
Keyword(s):  
Response Curve ◽  
Glass Temperature ◽  
Failure Envelope ◽  
Chain Flexibility ◽  
Maximum Value ◽  
Failure Envelopes ◽  
Common Response ◽  
The Common ◽  
The Difference ◽  
Two Parameters

Abstract At sufficiently high temperatures compared to the glass temperature, both experimental evidence (Figure 7) and Equation (10) predict that failure envelopes obtained from samples differing in νe will superpose to a common response curve f(ε) independent of chemical structure of the polymer when σb is normalized to unit νeT. At lower temperatures, experiment and Equation (8) indicate that in such a normalized plot, individual failure envelopes will diverge from the common response curve, f(ε), due primarily to the effect of the chain flexibility parameter n. As the temperature is lowered still further, Equation (6) shows that the shapes of individual envelopes may vary if the time dependences of E and g differ. This effect is presumably the factor which produces the difference in shapes between the Viton elastomers and the others shown in Figure 7. In addition, Equation (4) relates the maximum value which λb can attain to other readily measured parameters, notably νe. Thus knowledge of these two parameters, νe and n, is sufficient to predict to a good approximation the shape and location of the failure envelope up to the region of (λb)max.

Biomaterial Models Adjustment and Comparison for Ultra-High Molecular Weight Polyethylene in Finite Element Models

2018 ◽  
Author(s):  
Humberto Corro-Hernández ◽  
Agustín Vidal-Lesso ◽  
Elías Ledesma ◽  
Antonio de Jesús Balvantín-García
Keyword(s):  
Molecular Weight ◽  
Finite Element ◽  
High Molecular Weight ◽  
Numerical Solutions ◽  
Constant Strain Rate ◽  
Mechanical Tests ◽  
Isotropic Hardening ◽  
Load Curve ◽  
Prosthesis And Implants ◽  
Ultra High Molecular Weight

GUR1050 is a medical grade variety of ultra-high molecular weight polyethylene (UHMWPE) intended for use on total joint prosthesis and implants. Probes of this material were characterized on a compression test following ASTM norms and lineaments. Available data from these mechanical tests is fitted on multiple material models. Achieved results on numerical solutions of finite element modeling (FEM) of the tests are discussed, looking for the best one available in order to simulate with accuracy GUR1050 behavior, with specific interest on the load curve results, showing the pertinence of using certain models on different conditions. It was found that the use of a bilinear isotropic hardening model assures the best fit for GUR1050 behavior in uniaxial compression under a constant strain rate.

Study of Integration Strategy for Thermal-Elastic-Plastic Models

1992 ◽  
Vol 114 (1) ◽  
pp. 39-45 ◽  
Author(s):  
H.-K. Hong ◽  
H.-S. Lan ◽  
J.-K. Liou
Keyword(s):  
Strain Rate ◽  
Kinematic Hardening ◽  
Constant Strain Rate ◽  
Single Step ◽  
Rate Equations ◽  
Type Model ◽  
Integration Algorithm ◽  
First Order ◽  
Integration Strategy ◽  
Von Mises

The accuracy of a new integration algorithm is examined for a von Mises-type model of thermal-elastic-plasticity with nonlinear, mixed isotropic-kinematic hardening. The algorithm is founded on the frame of an integral representation of the conventional rate constitutive equations in contrast to the conventional rate equations themselves. The thermal effect on the yield surface is built in this approach without any difficulty. Under a generalized assumption of a constant strain rate, the model can be reduced to two scalar first-order ordinary differential equations which make an error-controllable integration method possible. Furthermore, for a nonconstant strain rate, e.g., a linear strain rate, the same idea of derivation achieves a similar conclusion. Errors of single-step stress predictions for given total strain increments are discussed.

Finite Element Implementation of a Thermoviscoplastic Model for Ratcheting

2004 ◽  
Author(s):  
Rashid K. Abu Al-Rub ◽  
George Z. Voyiadjis
Keyword(s):  
Finite Element ◽  
Strain Rate ◽  
Yield Criterion ◽  
Isotropic Hardening ◽  
Strain Rate Effects ◽  
Finite Element Implementation ◽  
Rate Dependent ◽  
Proposed Model ◽  
Integration Algorithms ◽  
Von Mises

A thermoviscoplastic constitutive model is proposed to simulate the uniaxial/multiaxial ratcheting of cyclically stable materials and its finite element implementation is also achieved. The kinematic and isotropic hardening rules used in the proposed model are similar to that developed by Voyiadjis and Abu Al-Rub [1], except for the coupling with temperature and strain-rate effects. The proposed constitutive equations include thermo-elasto-viscoplasticity, a dynamic yield criterion of a von Mises type, the associated flow rules, non-linear strain hardening, strain-rate hardening, and temperature softening. In the finite element implementation of the proposed model new implicit stress integration algorithms are proposed. The proposed unified integration algorithms are extensions of the classical rate-independent radial return scheme to the rate-dependent problems. A new expression of consistent tangent modulus is also derived for rate- and temperature-dependent inelasticity. The proposed model is verified by simulating the uniaxial ratcheting of a metallic material.

Ḥadith ‘Āishah fī Man’i al-Nisā’ Min al-Masājid; Niqāsh ‘Ulamā’ Bangladesh Ḥaulahu

2020 ◽  
Vol 9 (1) ◽  
pp. 97-115
Author(s):  
Syed Mahmudul Hasan
Keyword(s):  
Analytical Method ◽  
Inductive Method ◽  
The Common ◽  
The Difference ◽  
Common Situation

The Narration of Aisyah (May Allah be pleased with her), is the main focus of the controversy among Bangladeshi scholars on the issue of women's prayer in the mosque. The reason for the dispute is that a group of them issued the ruling based on the phenomenon of the text, and the others explained the ruling of Hadith according to the common situation in the society. If the circumstances change, the ruling will change along with it, because the originality of the issue is permissible, that is proven from other texts. This research adopts an inductive method to survey the Prophetic hadiths that talk about the prayer of women in the Mosque in terms of permissibility and prohibition and analytical method to analyze the difference in opinion of Bangladeshi scholars related to this issue. The research finds that the ruling of Shari’ah is a process that is continuous and permanent. But in necessity and emergency, it has the notion of flexibility and explanation. In the issue of women’s presence in the mosque, they should be allowed if they abide by the suggestions of Prophet (s) and should not if they don’t. So, Prohibition is not from the prophet (s), but it is from their obedience to the ruling.

Our Bodies, Whose Property?

2013 ◽  
Author(s):  
Anne Phillips
Keyword(s):  
Labor Markets ◽  
Personal Autonomy ◽  
The Body ◽  
Body Parts ◽  
Complex Issue ◽  
Human Organs ◽  
Property Owners ◽  
The Common ◽  
The Difference ◽  
The Right

No one wants to be treated like an object, regarded as an item of property, or put up for sale. Yet many people frame personal autonomy in terms of self-ownership, representing themselves as property owners with the right to do as they wish with their bodies. Others do not use the language of property, but are similarly insistent on the rights of free individuals to decide for themselves whether to engage in commercial transactions for sex, reproduction, or organ sales. Drawing on analyses of rape, surrogacy, and markets in human organs, this book challenges notions of freedom based on ownership of our bodies and argues against the normalization of markets in bodily services and parts. The book explores the risks associated with metaphors of property and the reasons why the commodification of the body remains problematic. The book asks what is wrong with thinking of oneself as the owner of one's body? What is wrong with making our bodies available for rent or sale? What, if anything, is the difference between markets in sex, reproduction, or human body parts, and the other markets we commonly applaud? The book contends that body markets occupy the outer edges of a continuum that is, in some way, a feature of all labor markets. But it also emphasizes that we all have bodies, and considers the implications of this otherwise banal fact for equality. Bodies remind us of shared vulnerability, alerting us to the common experience of living as embodied beings in the same world. Examining the complex issue of body exceptionalism, the book demonstrates that treating the body as property makes human equality harder to comprehend.

Between High Culture and Low Culture; and also The Difference Between Popular Culture and Folk Culture

2019 ◽  
Vol 7 (8) ◽  
pp. 12
Author(s):  
Kunal Debnath
Keyword(s):  
Popular Culture ◽  
Folk Culture ◽  
Common People ◽  
High Culture ◽  
The World ◽  
The Common ◽  
The Difference ◽  
Low Culture

High culture is a collection of ideologies, beliefs, thoughts, trends, practices and works-- intellectual or creative-- that is intended for refined, cultured and educated elite people. Low culture is the culture of the common people and the mass. Popular culture is something that is always, most importantly, related to everyday average people and their experiences of the world; it is urban, changing and consumeristic in nature. Folk culture is the culture of preindustrial (premarket, precommodity) communities.

FINANCIAL CONTROLLING IN THE SYSTEM OF FINANCIAL MANAGEMENT

2018 ◽  
Vol 28 (1) ◽  
pp. 137-141
Author(s):  
Petya Yordanova – Dinova
Keyword(s):  
Comparative Analysis ◽  
Financial Management ◽  
Financial Stability ◽  
Business Environment ◽  
Innovative Approach ◽  
Financial Sustainability ◽  
The Common ◽  
The Difference ◽  
Effective Use ◽  
And Control

This paper explores the comparative analysis of the financial controlling, who is a result from the common controlling concept and the financial management. In the specialized literature, financial controlling is seen as an innovative approach to financial management. It is often presented as the most promising instrument of financial diagnostics. Generally speaking, financial controlling is seen as a process of managing the company`s assets which are valued in monetary measures. The difference between the financial management and the financial controlling is that the second covers all functions of management, analysis and control of finances, aiming at maximizing their effective use and increasing the value of the enterprise. Financial controlling is often seen as a function of the common practice of financial management. Its objective is to preserve the financial stability and financial sustainability of enterprises operating in a highly aggressive business environment.

scholarly journals Plastic failure zone characteristics and stability control technology of roadway in the fault area under non-uniformly high geostress: A case study from Yuandian Coal Mine in Northern Anhui Province, China

2020 ◽  
Vol 12 (1) ◽  
pp. 406-424 ◽  
Author(s):  
Yaoguang Huang ◽  
Aining Zhao ◽  
Tianjun Zhang ◽  
Weibin Guo
Keyword(s):  
Numerical Methods ◽  
Numerical Solutions ◽  
Stress Test ◽  
Pressure Coefficient ◽  
Stability Control ◽  
Failure Zone ◽  
Plastic Failure ◽  
Comparison Results ◽  
High Geostress ◽  
The Difference

AbstractIn order to explore the effective support method for deep broken roadway, based on the in situ stress test results, the analytical and numerical solutions of the stress and the range of plastic failure zone (PFZ) in a circular roadway subjected to non-uniform loads were obtained using analytical and finite difference numerical methods based on the elastoplastic theory, respectively. Their comparison results show that the analytical and numerical methods are correct and reasonable. Furthermore, the high geostress causes the stress and range of PFZ in roadway roof and floor to increase sharply while those in roadway ribs decrease. Moreover, the greater the difference of horizontal geostress in different horizontal directions is, the larger the range of PFZ in roadway roof and floor is. The shape of PFZ in roadway varies with the ratio of horizontal lateral pressure coefficient in x-direction and y-direction. Finally, according to the distribution characteristics of PFZ and range of PFZ under the non-uniformly high geostress, this paper has proposed a combined support scheme, and refined and optimized supporting parameters. The field monitoring results prove that the roadway deformation and fracture have been effectively controlled. The research results of this paper can provide theoretical foundation as well as technical reference for the stability control of deep broken roadway under non-uniformly high geostress.

scholarly journals 0588 Ring Pulse Oximeter for Screening of Moderate to Severe OSA: A Pilot Study

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A225-A225
Author(s):  
J Xue ◽  
R Zhao ◽  
J Li ◽  
L Zhao ◽  
B Zhou ◽  
...  
Keyword(s):  
Pilot Study ◽  
Pulse Oximeter ◽  
Characteristic Curve ◽  
Diagnostic Value ◽  
Receiver Operator Characteristic Curve ◽  
Oxygen Desaturation ◽  
Significant Difference ◽  
Acceptance Range ◽  
The Difference ◽  
Two Parameters

Abstract Introduction To evaluate the utility of the ring pulse oximeter for screening of OSA in adults. Methods 87 adults were monitored by a ring pulse oximeter and PSG simultaneously during a nocturnal in-lab sleep testing. 3% oxygen desaturation index (ODI3); Mean oxygen saturation(MSpO2), Saturation impair time below 90% (SIT90) derived from an automated algorithm of the ring pulse oximeter. Meanwhile, the parameters of PSG were scored manually according to the AASM Manual. Correlation and receiver operator characteristic curve analysis were used to measure the accuracy of ring pulse oximeter and its diagnostic value for moderate to severe OSA (AHI≥15). Results Among the 87 participants, 18 cases were AHI<5, 17 cases were diagnosed with mild OSA (AHI:5-14.9), 25 cases were diagnosed with moderate OSA (AHI:15-29.9) and 27 cases were diagnosed with severe OSA (AHI≥30). There was no significant difference between PSG and ring pulse oximeter in regard to ODI3 (23.4±23.5 vs 24.7 ± 21.7), and SIT90 (1.54%, range 0.14%-8.99% vs. 3.20%, range 0.60%, 12.30%) (P>0.05], Further analysis indicated that two parameters from the oximeter correlated well with that derived from PSG (r=0.889, 0.567, respectively, both p<0.05). Although MSpO2 correlated significantly (r=0.448, P<0.05), the difference was remarkable [95.9%, range 94.0% to 97.0% vs. 94.5%, range 93.3% to 95.7%, p<0.05]. Bland-Altman plots showed that the agreement of these three parameters was within the clinical acceptance range. The ROC curve showed that the sensitivity and specificity of the ring pulse oximeter when the oximeter derived ODI3 ≥12.5 in the diagnosis of moderate to severe OSA were 82.7% and 74.3%, respectively. Conclusion The pilot study indicated that ring pulse oximeter can detect oxygen desaturation events accurately, therefore to be used as a screening tool for moderate to severe OSA. Support The study was supported by the National Natural Science Foundation of China (No. 81420108002 and NO. 81570083).

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