Buckling Delamination of the Rectangular Orthotropic Thick Plate With an Edge Rectangular Crack

2010 ◽  
Author(s):  
Surkay Akbarov ◽  
Nazmiye Yahnioglu ◽  
Esra Eylem Karatas
Keyword(s):  
Compressive Loading ◽  
Three Dimensional ◽  
Initial Imperfection ◽  
Critical Force ◽  
Geometrical Parameters ◽  
Field Equations ◽  
Rectangular Crack ◽  
Anisotropic Bodies ◽  
Buckling Delamination

The buckling delamination problem for the rectangular plate made from composite (orthotropic) material is studied. It is supposed that the plate has a rectangular edge-crack and edge-surfaces of that have an initial infinitesimal imperfection. The development of this initial imperfection with an external compressive loading acting along the crack is studied in the framework of the three-dimensional geometrically nonlinear field equations of the elasticity theory of anisotropic bodies. For the determination of the values of the critical force the initial imperfection criterion is used. The corresponding boundary-value problems are solved by employing the boundary form perturbation techniques and the FEM. The influence of the material or geometrical parameters of the plate on the values of critical force is discussed.

Buckling Delamination of a Rectangular Sandwich Thick Plate With Band Cracks

2010 ◽  
Author(s):  
Surkay Akbarov ◽  
Nazmiye Yahnioglu ◽  
Ayfer Tekin
Keyword(s):  
Thick Plate ◽  
Compressive Loading ◽  
Three Dimensional ◽  
Initial Imperfection ◽  
Core Layer ◽  
Solution Procedure ◽  
Critical Force ◽  
Geometrical Parameters ◽  
Field Equations ◽  
Buckling Delamination

The buckling delamination around the band cracks contained with the simply supported all edge-surface rectangular sandwich thick plate is investigated. It is assumed that the sandwich plate is composed of two face layers and a core layer. Face and core layers are made of different materials and it is assumed that there are two same cracks at the interfaces between the layers. Material of each layer is isotropic and homogeneous. For the solution procedure it is supposed that the surfaces of the cracks have insignificant initial imperfections. The development of this initial imperfection with an external compressive loading acting along the cracks is studied in the framework of the three dimensional geometrically nonlinear field equations of the elasticity theory and the piece-wise homogeneous body model. For the determination of the values of the critical force the initial imperfection criterion i.e. the case where the imperfection starts to increase and grows indefinitely, is used. The corresponding boundary value problems are solved by employing the boundary form perturbation techniques and the three dimensional FEM. The numerical results on the critical force are presented and analyzed. The influences of the material and geometrical parameters on these critical values are discussed.

Intellectual Measuring Complex for Control of Geometrical Parameters of Aviation Details

2020 ◽  
pp. 352-371
Author(s):  
Mariia Kataieva ◽  
Alina Yurchuk
Keyword(s):  
Computer Simulation ◽  
Measurement Error ◽  
Three Dimensional ◽  
Geometric Parameters ◽  
Measurement Process ◽  
Geometrical Parameters ◽  
Automated Method ◽  
Measuring Complex ◽  
Graphic Depiction

This chapter proposes a new automated method of measuring complex three-dimensional surfaces of aircraft parts in static and dynamic modes. The method allows conducting measurements in closed conditions and at the site of the aircraft disposition. The method consists in the continuous determination of the coordinates of the points of the surface of the detail and their representation in a three-dimensional graphic depiction. New methods of measuring the geometric parameters of parts with the complex spatial surface are suggested. This opens the prospect for the development of new ways of measuring geometric parameters of parts in real-time with high metrological characteristics and computer simulation of the measurement process. The differential-digital method is based on the suggested zero-coordinate principle of the measurement process which involves simultaneous parts availability check, and connects measurement result obtained which provided a reduction in the order of measurement error.

The Mechanics of Ideal Forming

1994 ◽  
Vol 61 (1) ◽  
pp. 176-181 ◽  
Author(s):  
K. Chung ◽  
O. Richmond
Keyword(s):  
Process Design ◽  
Three Dimensional ◽  
Field Equations ◽  
Starting Point ◽  
Deformation Processes ◽  
External Forces ◽  
Minimum Work ◽  
Yield Conditions ◽  
The Ideal

In this paper, the mechanics of ideal forming theory are summarized for general, three-dimensional, nonsteady processes. This theory has been developed for the initial stages of designing deformation processes. The objectives is to directly determine configurations, both initial and intermediate, that are required to ideally form a specified final shape. In the proposed theory, material elements are prescribed to deform along minimum plastic work paths, assuming that the materials have optimum formabilities in such paths. Then, the ideal forming processes are obtained so as to have the most uniform strain distributions in final products without shear tractions. As solutions, the theory provides the evolution of intermediate shapes of products and external forces as well as optimum strain distributions. Since the requirement of ideal forming to follow minimum work paths involves an over determination of the field equations, the theory places constraints on constitutive and boundary conditions. For example, tool interfaces must be frictionless and yield conditions must have vertices to achieve self-equilibrating three-dimensional deformations in most cases. Despite these constraints, the theory is believed to provide a useful starting point for deformation process design.

scholarly journals The use of a model current wedge in the determination of the position of substorm current systems

1995 ◽  
Vol 13 (6) ◽  
pp. 583-594 ◽  
Author(s):  
M. Cramoysan ◽  
R. Bunting ◽  
D. Orr
Keyword(s):  
Observation Interval ◽  
Three Dimensional ◽  
Secondary Process ◽  
Geometrical Parameters ◽  
Three Dimensional Model ◽  
Current Growth ◽  
Field Lines ◽  
Current Systems ◽  
Current Wedge

Abstract. We present a technique for determination of the position and extent of the current systems present during substorm breakup. The parameters of a three-dimensional model of the currents are determined by fitting the model to data from the SAMNET magnetometer array, a midlatitude array of seven stations. The model used is a fully 3D current wedge aligned along dipolar field lines, the parameters being the meridians of upward and downward field-aligned currents (FACs), the latitude of the auroral electrojet and the magnitude of current growth over the observation interval. The method is novel in that the three geometrical parameters are first determined with the fourth arrived at via a secondary process. It has been applied to a number of events and appears to make estimates of the longitudes of the FACs consistent with the predictions of previous methods. Since the method employs a fully 3D model of the substorm current wedge as opposed to an idealised 2D model, it is reasonable to place more reliance on the results so obtained. Moreover, the method also has the additional benefit of a prediction of the latitude of the substorm electrojet and the nature of the current growth through the wedge at substorm onset.

scholarly journals Application of various uncertainty measures in the problem of critical force searching for orthotropic shell in conditions of the carrying capacity

2021 ◽  
pp. 201-220
Author(s):  
Valerii Baranenko ◽  
Denys Volchok
Keyword(s):  
Bearing Capacity ◽  
Carrying Capacity ◽  
Orthotropic Shell ◽  
Orthotropic Cylindrical Shell ◽  
Random Variable ◽  
Statistical Simulation ◽  
Critical Force ◽  
Geometrical Parameters ◽  
Fuzzy Data

The questions of measures calculation of events containing uncertain quantities of random, fuzzy and rough nature are considered. The algorithms of determination of measures of events, based on methods of statistical simulation, are proposed. The "chances" of realization an uncertain event - the simultaneous fulfillment of the conditions of the bearing capacity of a cylindrical orthotropic shell compressed by an axial force, which can be presented in a random, fuzzy or rough manner, are investigated. The stochastic uncertainty is given by the distribution density of the random variable. Fuzzy data are defined by the membership function, and rough data are defined by a deterministic upper and lower approximation. Each type of uncertainty is characterized by its own measures: the probability - for the description of the modality - "probably", the possibility - for the description of the modality is "fuzzy", trust - to describe the modality "rough". The paper proposes procedures for calculating the listed measures. Also numerical illustrations of the calculation of modalities as "probably", "fuzzy", "rough" for the analysis of the limit force of carrying capacity in the problem of optimal design of the compressed orthotropic cylindrical shell made of fiberglass in conditions of uncertainty of the problem of geometrical parameters, such as thickness and radius, and description of the corresponding degree of implementation of an uncertain event are shown. Uncertain event is to fulfill the limitations of general and local stability and durability. The results of the calculations are compared with the solution of the problem with deterministic data. The results show the "reaction" of the values of the critical force to the possible presence of uncertain factors in the problem and the degree of uncertainty. Thus, the bearing capacity of the shell decreases significantly more in the presence of factors of random and rough nature in comparison to the fuzzy data.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

Determination of collapse moment of different angled pipe bends with initial geometric imperfection subjected to in-plane bending moments

2021 ◽  
pp. 095440622199640
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Circular Cross Section ◽  
Initial Imperfection ◽  
Bend Angle ◽  
Bending Moments ◽  
Element Analysis ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection

From the recent literature, it is revealed that pipe bend geometry deviates from the circular cross-section due to pipe bending process for any bend angle, and this deviation in the cross-section is defined as the initial geometric imperfection. This paper focuses on the determination of collapse moment of different angled pipe bends incorporated with initial geometric imperfection subjected to in-plane closing and opening bending moments. The three-dimensional finite element analysis is accounted for geometric as well as material nonlinearities. Python scripting is implemented for modeling the pipe bends with initial geometry imperfection. The twice-elastic-slope method is adopted to determine the collapse moments. From the results, it is observed that initial imperfection has significant impact on the collapse moment of pipe bends. It can be concluded that the effect of initial imperfection decreases with the decrease in bend angle from 150∘ to 45∘. Based on the finite element results, a simple collapse moment equation is proposed to predict the collapse moment for more accurate cross-section of the different angled pipe bends.

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