Bistable Behavior of the Cylindrical Origami Structure With Kresling Pattern

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Cai Jianguo ◽  
Deng Xiaowei ◽  
Zhou Ya ◽  
Feng Jian ◽  
Tu Yongming
Keyword(s):  
Strain Energy ◽  
Complex Case ◽  
Small Displacement ◽  
Cyclic Symmetry ◽  
Thin Cylindrical Shell ◽  
Bistable Behavior ◽  
Limit Condition ◽  
Bistable Phenomenon ◽  
Geometric Formulation ◽  
Made In

The deployment of a cylinder based on origami with Kresling pattern, whose basic mechanisms are formed by the buckling of a thin cylindrical shell under torsional loading, is studied in this paper. The model consists of identical triangular panels with cyclic symmetry and has a small displacement internal inextensional mechanism. First, geometric formulation of the design problem is presented. Then, assuming that the deployment and folding process is uniform, the bistable behavior of the cylinder is discussed. It can be found that, during the deployment, the dimensionless strain energy increases first and then reduces to zero but followed by another sharp increase. Moreover, the limit condition of geometry parameters for the bistable phenomenon is also discussed. Finally, the bistable behavior is also studied by using numerical simulations for simple and more complex case of the cylinder with multistory. The numerical results agree well with the analytical predictions. Therefore, comparisons with finite element predictions have shown that the analytical solutions given in this paper are accurate and have validated the assumptions made in the derivations.

A New Progressive Curvilinear Strain Energy-Based Crack Growth Modeling Algorithm Using Multicomplex Variable Finite Elements

2014 ◽  
Vol 891-892 ◽  
pp. 1015-1020
Author(s):  
Harry Millwater ◽  
David Wagner
Keyword(s):  
Crack Growth ◽  
Strain Energy ◽  
Fracture Analysis ◽  
Critical Importance ◽  
Significant Progress ◽  
Progressive Fracture ◽  
Technical Issues ◽  
Crack Growth Modeling ◽  
Progressive Strain ◽  
Made In

Arbitrary, non-planar progressive fracture analysis is of critical importance to the integrity of structures. While significant progress has been made in the last 25 years, there are still technical issues regarding computational expense, robustness, and accuracy. Based upon the recent significant enhancements available through the use of multicomplex finite element methods, a new high-order progressive strain energy based progressive crack growth algorithm is proposed.

scholarly journals Optimal Plastic Analysis and Design of Pile Foundations Under Reliable Conditions

2021 ◽  
Author(s):  
Majid Movahedi Rad ◽  
Sarah Khaleel Ibrahim
Keyword(s):  
Strain Energy ◽  
Limit Load ◽  
Pile Foundations ◽  
Design Parameters ◽  
Plastic Limit ◽  
Limit Condition ◽  
Analysis And Design ◽  
Residual Displacements ◽  
Complementary Strain ◽  
Plastic Limit Load

In this research, in order to evaluate the plastic limit load and also plastic design parameters of the long pile foundations subjected to horizontal loads, shakedown method is applied. In carrying out shakedown analysis and design methods, large plastic deformations and residual displacements could develop in the pile foundation which might lead to the failure of the structure. For this reason, complementary strain energy of residual forces proposed as a limit condition to control the plastic deformation of the pile structure. Furthermore, considering the uncertainties (strength, manufacturing, geometry) the limit conditions on the complementary strain energy of residual forces are assumed randomly and the reliability condition was formed by the use of the strict reliability index. The influence of the limit conditions on the plastic limit load and design parameters of the long pile in cohesionless soil subjected to lateral load were investigated and limit curves for shakedown load factors are presented. The numerical results show that the probabilistic given limit conditions on the complementary strain energy of residual forces have significant influence on the load bearing limit and the design parameters of pile foundations. The formulations of the reliability based problems lead to mathematical programming which were carried out by the use of non-linear algorithm.

scholarly journals Strain energy method for solving wave problems of a flexible thread

2020 ◽  
Author(s):  
A.V. Bryukvin ◽  
O.Yu. Bryukvina
Keyword(s):  
Wave Propagation ◽  
Strain Energy ◽  
Wave Perturbation ◽  
Transverse Waves ◽  
Before And After ◽  
Pass Through ◽  
Wave Problems ◽  
Strain Energy Method ◽  
Front Zone ◽  
Made In

The paper considers the behavior of a flexible deformable thread when longitudinal and transverse waves pass through it. The processes occurring in a thread during the passage of a wave perturbation through it are analyzed under the assumption that the wave front zone is limited comparing with the length of the thread but not assuming this quantity to be of infinite smallness. In contrast to other similar works, no assumptions were made in advance about the shape of the thread in the zone of the wave perturbation passage (the fracture of the thread) and the dependence of the tension force on its elongation. The only requirement is the implementation of the general theorems of dynamics. Formulas for the relation of the thread speed before and after the passage of the wave with a change in the angle of thread inclination are obtained making possible solving wave propagation problems in a new way. The method is illustrated by new solutions to known problems, which allows comparing the obtained results with known solutions and verifying the advantages of the proposed method.

THE THEORY OF ULTRASONIC ABSORPTION: RELAXATION OF TWO INTERACTING REACTIONS

1964 ◽  
Vol 42 (5) ◽  
pp. 1174-1185 ◽  
Author(s):  
J. P. Valleau
Keyword(s):  
Linear Theory ◽  
Viscosity Coefficient ◽  
Complex Case ◽  
Ultrasonic Absorption ◽  
Sound Waves ◽  
Physical Chemical ◽  
Explicit Formulae ◽  
Dependent Viscosity ◽  
Absorption And Dispersion ◽  
Made In

The purpose of this paper is to extend the theory of ultrasonic absorption in fluids to the case of the relaxations of two interacting reactions. The linear theory of the absorption and dispersion of sound waves is developed in terms of a frequency-dependent viscosity coefficient. This coefficient is then evaluated for the familiar case of a single relaxing reaction and for the more complex case of two reactions interacting in an arbitrary way. The absorption and dispersion of the sound waves are related to familiar physical chemical quantities by explicit formulae, and non-ideality has been taken account of by the use of activity coefficients. Some discussion of the results is presented. The intention of this development is to make possible the extraction of physical chemical data from ultrasonic investigations of systems involving interacting equilibria, and such an application has been made in an accompanying paper.

On the Choice of Strain Energy Function for Mechanical Characterisation of Soft Biological Tissues

1984 ◽  
Vol 13 (1) ◽  
pp. 11-14 ◽  
Author(s):  
K B Sahay
Keyword(s):  
Energy Function ◽  
Constitutive Equations ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Biological Tissues ◽  
Energy Functions ◽  
Soft Biological Tissues ◽  
Mechanical Characterisation ◽  
Strain Energy Functions ◽  
Made In

Constitutive equations that describe stress–strain relations of soft biological tissues require parameters such as the strain energy functions, or certain of their derivatives. An attempt has been made in this paper to examine the suitability of the various strain energy functions reported in the literature. Certain criteria are proposed for the same.

The Folding of Triangulated Cylinders, Part I: Geometric Considerations

1994 ◽  
Vol 61 (4) ◽  
pp. 773-777 ◽  
Author(s):  
S. D. Guest ◽  
S. Pellegrino
Keyword(s):  
Cylindrical Shell ◽  
Design Parameters ◽  
Small Displacement ◽  
Generic Type ◽  
Folding Process ◽  
Small Strains ◽  
Biological Structures ◽  
Geometric Formulation

This study was inspired by a model of a triangulated cylindrical shell made by C. R. Calladine during an investigation of the mechanics of biological structures. The model consisted of identical triangular panels on a helical strip and had a small-displacement internal inextensional mechanism. It is shown that many triangulated cylinders broadly similar to Calladine’s model can be folded down to a compact stack of plates: only small strains, whose magnitude can be made arbitrarily small by the choice of suitable design parameters, are imposed during folding. A general geometric formulation of the problem is presented and then, assuming that the folding process is uniform, the folding properties of any triangulated cylinder of this generic type are discussed.

Principle of Stress Rate in the Instability of Trusses

2012 ◽  
Vol 193-194 ◽  
pp. 868-871
Author(s):  
Wen Feng Du ◽  
Fu Dong Yu
Keyword(s):  
Strain Energy ◽  
Dynamic Instability ◽  
Stress Rate ◽  
Truss Structures ◽  
Global Instability ◽  
Total Strain Energy ◽  
Relationship Of ◽  
The Relationship ◽  
Rate Criterion ◽  
Made In

How to judge the dynamic instability of trusses is an important problem. It is found that stress rate of a truss has the catastrophic characters when trusses are out of stability. According to the relationship of the total strain energy and the stress rate, the principle of stress rate is proposed , that the dynamic instability was made in structures if the stress rate was suddenly changed to a relative very great value. Some examples, such as a dome shell, a three-bar spatial frame, a plane truss, and so on, are discussed. The results showed that it was effective to judge the instability of truss structures by using the tress rate criterion. By comparison of the stress rate criterion with the displacement criterion it can be obtained that the result of displacement criterion was comparatively obvious in the global instability while the result of stress rate criterion was more ocular in judging the local instability in truss structures.

Transversely Isotropic Hyperelastic Constitutive Models for Plastic Thermoforming Simulation

2013 ◽  
Vol 554-557 ◽  
pp. 1715-1728 ◽  
Author(s):  
Zied Oueslati ◽  
Mohamed Rachik ◽  
Marie France Lacrampe
Keyword(s):  
Constitutive Modeling ◽  
Strain Energy ◽  
Soft Tissues ◽  
Measurement Data ◽  
Constitutive Models ◽  
Transversely Isotropic ◽  
Tensile Tests ◽  
Energy Potential ◽  
Transversally Isotropic ◽  
Made In

For several years, modeling hyperelasticity has been focused on and leaded to a large choice of strain energy potential forms. Since then, many advances have been made in constitutive modeling of rubber like materials. These models are nowadays widely used in many applications like constitutive modeling of soft tissues in biomechanics problems or plastic thermoforming simulation. In this work, constitutive modeling of TPO sheets for thermoforming application is considered. Experimental measurements have shown that the material is transversely isotropic. To take into account this anisotropy, we implemented some new transversally isotropic hyperelastic constitutive models in Abaqus software with the help of user subroutines. Furthermore, different particular forms of the strain energy potential are investigated and their hyperelatic constants are fitted to the measurement data from tensile tests performed in different directions. Based on the results of these investigations, a transversely isotropic form of the energy potential derived from the Yeoh constitutive model is adopted and several tests are analyzed for validation purpose. The chosen model is a good compromise that achieves accurate predictions with limited amount of tests and limited identification efforts. Another key finding of this work is the influence of the anisotropy on the thermoformed parts.

Spectrophotometric measurements of objective-prism spectra

1966 ◽  
Vol 24 ◽  
pp. 118-119
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Progress Report ◽  
Two Dimensional ◽  
Objective Prism ◽  
Made In

I should like to give you a very condensed progress report on some spectrophotometric measurements of objective-prism spectra made in collaboration with H. Leicher at Bonn. The procedure used is almost completely automatic. The measurements are made with the help of a semi-automatic fully digitized registering microphotometer constructed by Hög-Hamburg. The reductions are carried out with the aid of a number of interconnected programmes written for the computer IBM 7090, beginning with the output of the photometer in the form of punched cards and ending with the printing-out of the final two-dimensional classifications.

Surface Structure in Microtomed Sections Caused by Glass and Diamond Knives

1971 ◽  
Vol 29 ◽  
pp. 456-457
Author(s):  
J. Temple Black ◽  
William G. Boldosser
Keyword(s):  
Plastic Deformation ◽  
Epoxy Resin ◽  
Carbon Coating ◽  
Surface Damage ◽  
Body Angle ◽  
Normal Manner ◽  
Bottom Side ◽  
Cutting Direction ◽  
Made In ◽  
Diamond Knife

Ultramicrotomy produces plastic deformation in the surfaces of microtomed TEM specimens which can not generally be observed unless special preparations are made. In this study, a typical biological composite of tissue (infundibular thoracic attachment) infiltrated in the normal manner with an embedding epoxy resin (Epon 812 in a 60/40 mixture) was microtomed with glass and diamond knives, both with 45 degree body angle. Sectioning was done in Portor Blum Mt-2 and Mt-1 microtomes. Sections were collected on formvar coated grids so that both the top side and the bottom side of the sections could be examined. Sections were then placed in a vacuum evaporator and self-shadowed with carbon. Some were chromium shadowed at a 30 degree angle. The sections were then examined in a Phillips 300 TEM at 60kv.Carbon coating (C) or carbon coating with chrom shadowing (C-Ch) makes in effect, single stage replicas of the surfaces of the sections and thus allows the damage in the surfaces to be observable in the TEM. Figure 1 (see key to figures) shows the bottom side of a diamond knife section, carbon self-shadowed and chrom shadowed perpendicular to the cutting direction. Very fine knife marks and surface damage can be observed.

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