scholarly journals Science intensive technologies in shaping at current stage of mechanical engineering development

2016 ◽  
Vol 1 (4) ◽  
pp. 10-13 ◽  
Author(s):  
В. Демин ◽  
V. Demin
Keyword(s):  
Computational Modeling ◽  
Mechanical Engineering ◽  
Experiment Planning ◽  
Material Structure ◽  
Problem Solution ◽  
Stress Strain ◽  
Anisotropic Stress ◽  
Metal Stamping ◽  
Metal Shaping ◽  
Current Stage

Current approaches to the analysis of metal shaping. It is pointed out that at the current stage it is necessary to design processes ensuring a specified material structure and an essential reserve of plasticity. Particular consideration is given to the problem of manufacturing products of powder and incompact materials. The approaches to the problem solution of metal stamping having anisotropic stress-strain properties are widely covered. It is offered to use methods of experiment planning for processing the results of computational modeling. It is offered to include random characteristics into a solution which could change at new metal lot obtaining. It is shown that changes in geometry, techniques and stress-strain properties can result in the considerable changes of values during metal shaping.

A Stochastic Method to Estimate the Anisotropic Stress-Dependent Coal Permeability by Pore-Volume Distribution and Stress-Strain Measurements

SPE Journal ◽  
2020 ◽  
Vol 25 (05) ◽  
pp. 2582-2600
Author(s):  
Syed Shabbar Raza ◽  
Victor Rudolph ◽  
Tom Rufford ◽  
Zhongwei Chen
Keyword(s):  
History Matching ◽  
Absolute Magnitude ◽  
Volume Distribution ◽  
Stress Strain ◽  
Anisotropic Permeability ◽  
Anisotropic Stress ◽  
Flow Channels ◽  
Measured Stress ◽  
Stress Dependent ◽  
Or History

Summary A novel, simple, economical, and time-effective method to estimate the anisotropic permeability of coal is presented in this paper. This method estimates the coal’s anisotropic permeability by avoiding the tedious experimentation using triaxial permeameter or history-matching exercises. This method calculates the absolute magnitude of the permeability of the sample. In this regard, it is unlike other analytical permeability models, such as given by Palmer and Mansoori (1998) and Shi and Durucan (2014), that only calculate the permeability ratio (k/k0). The motivation is to find a method by which the permeability of the coal may be determined with reasonable accuracy by using only two easy measurements: mercury intrusion porosimetry (MIP) and anisotropic stress-strain (σ-ɛ) measurement. The main blocks of the method are based on cleat size that is obtained from MIP and randomly allocated to form flow channels/cleats through the coal; these cleats form parallel paths in the orthogonal face and butt cleat directions that provide the permeability; and the cleat width (b) is stress dependent. This method is further validated by comparing with the experimentally measured stress-dependent permeability of Surat Basin (Australia) coal and German coal in face cleat and butt cleat directions.

Mimicking “J-Shaped” and Anisotropic Stress–Strain Behavior of Human and Porcine Aorta by Fabric-Reinforced Elastomer Composites

2019 ◽  
Vol 11 (36) ◽  
pp. 33323-33335 ◽  
Author(s):  
Dinara Zhalmuratova ◽  
Thanh-Giang La ◽  
Katherine Ting-Ting Yu ◽  
Alexander R. A. Szojka ◽  
Stephen H. J. Andrews ◽  
...  
Keyword(s):  
Stress Strain ◽  
Anisotropic Stress ◽  
Strain Behavior ◽  
Elastomer Composites

Development of a Flow Evolution Network Model for the Stress–Strain Behavior of Poly(L-lactide)

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Maureen L. Dreher ◽  
Srinidhi Nagaraja ◽  
Jorgen Bergstrom ◽  
Danika Hayman
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Computational Modeling ◽  
Medical Devices ◽  
Constitutive Models ◽  
Constitutive Relationship ◽  
Displacement Curve ◽  
Stress Strain ◽  
Strain Behavior ◽  
Flow Evolution

Computational modeling is critical to medical device development and has grown in its utility for predicting device performance. Additionally, there is an increasing trend to use absorbable polymers for the manufacturing of medical devices. However, computational modeling of absorbable devices is hampered by a lack of appropriate constitutive models that capture their viscoelasticity and postyield behavior. The objective of this study was to develop a constitutive model that incorporated viscoplasticity for a common medical absorbable polymer. Microtensile bars of poly(L-lactide) (PLLA) were studied experimentally to evaluate their monotonic, cyclic, unloading, and relaxation behavior as well as rate dependencies under physiological conditions. The data were then fit to a viscoplastic flow evolution network (FEN) constitutive model. PLLA exhibited rate-dependent stress–strain behavior with significant postyield softening and stress relaxation. The FEN model was able to capture these relevant mechanical behaviors well with high accuracy. In addition, the suitability of the FEN model for predicting the stress–strain behavior of PLLA medical devices was investigated using finite element (FE) simulations of nonstandard geometries. The nonstandard geometries chosen were representative of generic PLLA cardiovascular stent subunits. These finite element simulations demonstrated that modeling PLLA using the FEN constitutive relationship accurately reproduced the specimen’s force–displacement curve, and therefore, is a suitable relationship to use when simulating stress distribution in PLLA medical devices. This study demonstrates the utility of an advanced constitutive model that incorporates viscoplasticity for simulating PLLA mechanical behavior.

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