scholarly journals Swelling and shrinking in prestressed polymer gels: an incremental stress–diffusion analysis

2019 ◽  
Vol 475 (2230) ◽  
pp. 20190174 ◽  
Author(s):  
Marco Rossi ◽  
Paola Nardinocchi ◽  
Thomas Wallmersperger
Keyword(s):  
Chemical Potential ◽  
Polymer Gels ◽  
Mechanical Analysis ◽  
Test Case ◽  
Diffusion Analysis ◽  
Stress Diffusion ◽  
Nonlinear Stress ◽  
Deformation State ◽  
Poroelastic Theory ◽  
Elastic Constraint

Polymer gels are porous fluid-saturated materials which can swell or shrink triggered by various stimuli. The swelling/shrinking-induced deformation can generate large stresses which may lead to the failure of the material. In the present research, a nonlinear stress–diffusion model is employed to investigate the stress and the deformation state arising in hydrated constrained polymer gels when subject to a varying chemical potential. Two different constraint configurations are taken into account: (i) elastic constraint along the thickness direction and (ii) plane elastic constraint. The first step entirely defines a compressed/tensed configuration. From there, an incremental chemo-mechanical analysis is presented. The derived model extends the classical linear poroelastic theory with respect to a prestressed configuration. Finally, the comparison between the analytical results obtained by the proposed model and a particular problem already discussed in literature for a stress-free gel membrane (one-dimensional test case) will highlight the relevance of the derived model.

Finite Element Transient Modelling for Aero-Thermo-Mechanical Analysis of Whole Gas Turbine Engine

2019 ◽  
Author(s):  
Sabrina Giuntini ◽  
Antonio Andreini ◽  
Bruno Facchini
Keyword(s):  
Gas Turbines ◽  
Structural Integrity ◽  
Numerical Procedure ◽  
Mechanical Analysis ◽  
Operating Conditions ◽  
Test Case ◽  
Large Power ◽  
Turbine Engine ◽  
Air System ◽  
Secondary Air

Abstract It is here proposed a numerical procedure aimed to perform transient aero-thermo-mechanical calculations of large power generation gas turbines. Due to the frequent startups and shutdowns that nowadays these engines encounter, procedures for multi-physics simulations have to take into account the complex coupled interactions related to inertial and thermal loads, and seal running clearances. In order to develop suitable secondary air system configurations, guarantee structural integrity and maintain actual clearances and temperature peaks in pre-established ranges, the overall complexity of the structure has to be reproduced with a whole engine modelling approach, simulating the entire machine in the real operating conditions. In the proposed methodology the aerodynamic solution providing mass flows and pressures, and the thermo-mechanical analysis returning temperatures and material expansion, are performed separately. The procedure faces the aero-thermo-mechanical problem with an iterative process with the aim of taking into account the complex aero-thermo-mechanical interactions actually characterizing a real engine, in a robust and modular tool, combining secondary air system, thermal and mechanical analysis. The heat conduction in the solid and the fluid-solid heat transfer are computed by a customized version of the open source FEM solver CalculiX®. The secondary air system is modelled by a customized version of the embedded CalculiX® one-dimensional fluid network solver. In order to assess the physical coherence of the presented methodology the procedure has been applied to a test case representative of a portion of a real engine geometry, tested in a thermal transient cycle for the assessment of the interaction between secondary air system properties and geometry deformations.

Numerical Analysis in the Process of Alternate Pressing and Multiaxial Compression

2012 ◽  
Vol 706-709 ◽  
pp. 1763-1768
Author(s):  
Marcin Kwapisz ◽  
Marcin Knapiński ◽  
Henryk Dyja ◽  
Konrad Błażej Laber
Keyword(s):  
Numerical Analysis ◽  
Equal Channel Angular Pressing ◽  
Mechanical Analysis ◽  
Strain Accumulation ◽  
Angular Pressing ◽  
Grain Crushing ◽  
Compression Strain ◽  
Numeric Simulation ◽  
Multiaxial Compression ◽  
Deformation State

This article presents the results of numeric simulation obtained with commercial software for thermo-mechanical analysis of plastic forging processes, Forge 2009, of the process of alternate forced pressing and multiaxial compression. The new method of alternate forced pressing and multiaxial compression suggested by the authors is characterized by the presence in the plastically forged material of the similar states of deformations to those present in the processes of the equal channel angular pressing and cyclic extrusion compressing. From the performed preliminary tests it can be stated that as a result of combining and repeating two alternate operations: pressing and multiaxial compression, strain accumulation and development of deformation state favorable to grain crushing take place.

scholarly journals Explorative Study on the Use of Curauá Reinforced Polypropylene Composites for the Automotive Industry

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4185 ◽  
Author(s):  
Marc Delgado-Aguilar ◽  
Quim Tarrés ◽  
María de Fátima V. Marques ◽  
Francesc X. Espinach ◽  
Fernando Julián ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Automotive Industry ◽  
Natural Fiber ◽  
Natural Fibers ◽  
Stress Transfer ◽  
Mechanical Analysis ◽  
Test Case ◽  
Polypropylene Composites ◽  
Important Challenge ◽  
Promising Source

The automotive industry is under a growing volume of regulations regarding environmental impact and component recycling. Nowadays, glass fiber-based composites are commodities in the automotive industry, but show limitations when recycled. Thus, attention is being devoted to alternative reinforcements like natural fibers. Curauá (Curacao, Ananas erectifolius) is reported in the literature as a promising source of natural fiber prone to be used as composite reinforcement. Nonetheless, one important challenge is to obtain properly dispersed materials, especially when the percentages of reinforcements are higher than 30 wt %. In this work, composite materials with curauá fiber contents ranging from 20 wt % to 50 wt % showed a linear positive evolution of its tensile strength and Young’s modulus against reinforcement content. This is an indication of good reinforcement dispersion and of favorable stress transfer at the fiber-matrix interphase. A car door handle was used as a test case to assess the suitability of curauá-based composites to replace glass fiber-reinforced composites. The mechanical analysis and a preliminary lifecycle analysis are performed to prove such ability.

scholarly journals Nonlinear Elastic Foundation Plate Model Study on Overlying Strata Movement in Working Face with Solid Backfilling Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Baifu An ◽  
Nailu Li ◽  
Qiaomei Yi ◽  
Dong Zhang ◽  
Hailong Wang
Keyword(s):  
Elastic Foundation ◽  
Mechanical Analysis ◽  
Stress Strain ◽  
Nonlinear Elastic Foundation ◽  
Model Study ◽  
Working Face ◽  
Geological Conditions ◽  
Nonlinear Stress ◽  
Foundation Plate ◽  
Nonlinear Elastic

Although solid backfilling materials are featured with obvious nonlinear stress-strain properties, for a long time, they have been usually simplified as linear elastic materials for approximate calculation in mechanical analysis, so it is difficult to accurately reflect their deformation process. Based on test results of solid backfilling materials’ compaction characteristics, this paper provides a solution method to generate their elastic foundation coefficient. One multiparameter elastic foundation has been used to reflect stress-strain characteristics of solid backfilling material. In addition, the paper establishes a thin plate on a nonlinear elastic foundation model by adopting semianalytical and seminumerical method and obtains the relational expression between roof deflection, roof stress, and backfilling material’s compressive deformation. In combination with geological conditions in a specific mine, the paper probes into what influence both backfilling material’s particle size and the initial compaction force that the backfilling material bears could exert on roof subsidence and stress. Finally, the proposed model has been verified with measured data from industrial tests.

scholarly journals Exploration of Equivalent Design Approaches for Tanks Transporting Flammable Liquids

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 33
Author(s):  
Dimitrios Koulocheris ◽  
Clio Vossou
Keyword(s):  
Structural Integrity ◽  
Construction Material ◽  
Mechanical Analysis ◽  
Liquid Fuels ◽  
Test Case ◽  
Road Transportation ◽  
Minimum Thickness ◽  
The Road ◽  
Dangerous Goods ◽  
Tank Vehicles

Tank vehicles are widely used for the road transportation of dangerous goods and especially flammable liquid fuels. Existing gross weight limitations, in such transportations, render the self-weight of the tank structure a crucial parameter of the design. For the design and the construction of metallic tank vehicles carrying dangerous goods, the European Standard EN13094:2015 is applied. This Standard poses a minimum thickness for the shell thickness for the tank construction according to the mechanical properties of the construction material. In the present paper, primarily, the proposed design was investigated and a weight minimization of such a tank vehicle with respect to its structural integrity was performed. As test case, a tank vehicle with a box-shaped cross-section and low gross weight was considered. For the evaluation of the structural integrity of the tank construction, the mechanical analysis software ANSYS ® 2019R1 was used. The boundary values and the suitable computation for structural integrity were applied, as they are defined in the corresponding Standards. The thickness of the construction material was decreased to a minimum, lower than that posed by the standards, indicating that the limit posed by them was by no means boundary in terms of structural integrity.

scholarly journals Modeling solvent dynamics in polymers with solvent-filled cavities

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Michele Curatolo ◽  
Paola Nardinocchi ◽  
Luciano Teresi
Keyword(s):  
Hollow Spheres ◽  
Polymer Gels ◽  
Finite Element Code ◽  
Cavity Volume ◽  
Solvent Dynamics ◽  
Stress Diffusion ◽  
External Conditions ◽  
Stress States ◽  
As Stress ◽  
The Mathematical Model

AbstractDynamics of solvent release from polymer gels with small solvent-filled cavities is investigated starting from a thermodynamically consistent and enriched multiphysics stress-diffusion model. Indeed, the modeling also accounts for a new global volumetric constraint which makes the volume of the solvent in the cavity and the cavity volume equal at all times. This induces a characteristic suction effect into the model through a negative pressure acting on the cavity walls. The problem is solved for gel-based spherical microcapsules and microtubules. The implementation of the mathematical model into a finite element code allows to quantitatively describe and compare the dynamics of solvent release from full spheres, hollow spheres, and tubules in terms of a few key quantities such as stress states and amount of released solvent under the same external conditions.

707 Evaluation of Grain Shape Effect on Tin Whisker Growth by Stress-Diffusion Analysis

2008 ◽  
Vol 2008.21 (0) ◽  
pp. 289-290
Author(s):  
T. Suzuki ◽  
Y. Okura ◽  
T. Terasaki ◽  
T. Iwasaki ◽  
T. Kato ◽  
...  
Keyword(s):  
Whisker Growth ◽  
Grain Shape ◽  
Shape Effect ◽  
Tin Whisker ◽  
Diffusion Analysis ◽  
Stress Diffusion
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