The Stochastic Imperfection Method of Sheet Space Structure Based on Truncated Univariate Normal Distributions

2014 ◽  
Vol 937 ◽  
pp. 707-711
Author(s):  
Tian Jiao Jin ◽  
Xiao Ming Guo
Keyword(s):  
Space Structure ◽  
Acceptance Rate ◽  
Space Structures ◽  
Design Code ◽  
Geometric Imperfections ◽  
Spherical Coordinate ◽  
Normal Distributions ◽  
Truncated Normal ◽  
Initial Geometric Imperfections ◽  
The Stability

The initial geometric imperfections is a key issue of the stability analysis of sheet space structures. A new described method of the initial geometric imperfections which is located in local spherical coordinate system is given, and the random imperfection variable is assumed to follow a truncated univariate normal distribution (TUVN). A well working envelope function for TUVN is chosen, and the acceptance rate is high for constrained region of the design code. The method provided in the paper is called spherical truncated normal stochastic imperfection method (STNS). The results of consistent mode imperfections method, traditional stochastic imperfection method and STNS method are compared, by which some conclusions that are useful for the design and the study of sheet space structures are obtained.

The Imperfection Sensitivity of Sheet Space Structure Based on the Contact Interactive

2012 ◽  
Vol 204-208 ◽  
pp. 1260-1266
Author(s):  
Tian Jiao Jin ◽  
Xiao Ming Guo ◽  
Wei Sun
Keyword(s):  
Critical Load ◽  
Space Structure ◽  
Space Structures ◽  
Imperfection Sensitivity ◽  
Distribution Law ◽  
Sample Number ◽  
Key Issues ◽  
Initial Geometric Imperfections ◽  
The Stability ◽  
Quantitative Indicators

The initial geometric imperfections and the contact problem between sheets and skeletons are two key issues of the stability analysis of sheet space structures. In this paper ,the distribution law of the critical load is found out, the appropriate sample number and the critical load value formula are chosen for stochastic imperfection method, while the value of probability reliability is ensured. The results of contact model and fully coordinated model are compared to indicate that the effect of contact must be considered in the imperfection sensitive analysis of the structure after stochastic imperfection sensitivity analysis of sheet space structures. The paper also raises the quantitative indicators to characterize the imperfection sensitivity of sheet space structure, and it is the necessary preparation to quantify the sensitivity of structures.

scholarly journals Numerical analysis of stability of the stiffened plates subjected aliquant critical loads

2020 ◽  
Vol 16 (1) ◽  
pp. 54-61
Author(s):  
Gaik A. Manuylov ◽  
Sergey B. Kositsyn ◽  
Irina E. Grudtsyna
Keyword(s):  
Numerical Analysis ◽  
Critical Loads ◽  
Geometric Nonlinearity ◽  
Compressive Load ◽  
Stiffened Plates ◽  
Geometric Imperfections ◽  
Initial Geometric Imperfections ◽  
Analysis Of Stability ◽  
The Stability

The aim of the work is to research the precritical and postcritical equilibrium of the stiffened plates subjected aliquant critical loads. Methods. The finiteelement complex MSC PATRAN - NASTRAN was used in the paper. To simulate the plates, flat four-node elements were used. Calculations taking into account geometric nonlinearity were carried out. The material of the shells was considered absolutely elastic. Results. A technique has been developed to study the stability of reinforced longitudinally compressed plates; the critical forces of the stiffened plates of various thicknesses had been calculated. Graphs of deflections dependences on the value of the compressive load had been constructed. The influence of initial geometric imperfections on the value of the critical loads for stiffened plates has been investigated.

One-Way Buckling of Circular Rings Confined Within a Rigid Boundary

1995 ◽  
Vol 117 (2) ◽  
pp. 162-169 ◽  
Author(s):  
C. Sun ◽  
W. J. D. Shaw ◽  
A. M. Vinogradov
Keyword(s):  
Critical Condition ◽  
Experimental Approach ◽  
Equilibrium Analysis ◽  
Initial Deflection ◽  
Rigid Boundary ◽  
Geometric Imperfections ◽  
Circular Rings ◽  
Initial Geometric Imperfections ◽  
The Stability ◽  
Theoretical Results

The stability of a ring confined by a rigid boundary, subjected to circumferential end loads, is investigated both theoretically and experimentally. The effect of initial geometric imperfections on the buckling load is determined by assuming an initial deflection configuration as a simple sine form and the critical condition was derived from equilibrium analysis. An experimental approach was designed to verify the analytical results. Comparison with other theoretical results are also made.

scholarly journals Numerical modelingof a composite section element from thin-walled profiles taking into account the initial geometric imperfections

2020 ◽  
Vol 17 (1) ◽  
pp. 82-86
Author(s):  
D. A. Prostakishina ◽  
◽  
N. D. Korsun ◽  
Keyword(s):  
Bearing Capacity ◽  
Compressive Force ◽  
Stability Loss ◽  
Load Bearing Capacity ◽  
Geometric Imperfections ◽  
Load Bearing ◽  
Composite Section ◽  
Initial Geometric Imperfections ◽  
Thin Walled ◽  
The Stability

The article describes the process of numerical simulation of a composite symmetric section element made of thin-walled Sigma profiles operating under conditions of longitudinal compressive force with bending, taking into account the initial geometric imperfections. At numerical modeling, the main criterion of the load-bearing capacity exhaustion in case of eccentric compression is the stability loss in one of the forms. However, for thin-walled elements, the loss of local stability does not mean that the load-bearing capacity is completely exhausted, since the element continues to carry the load, but to a lesser extent. Therefore, simulation was carried out in two stages: initially, in the elastic formulation, the possible buckling modes were determined, afterwards, there was made calculation on the deformed pattern taking into account possible imperfections.

Application of Modified Consistent Mode Imperfection Method in Stability Analysis of Single-Layer Reticulated Shells

2013 ◽  
Vol 477-478 ◽  
pp. 744-748 ◽  
Author(s):  
Sheng He ◽  
Jian Cai ◽  
Qi Qi Liu
Keyword(s):  
Stability Analysis ◽  
Single Layer ◽  
Buckling Load ◽  
Structure Stability ◽  
Geometric Imperfections ◽  
Stability Performance ◽  
Mode Method ◽  
Initial Geometric Imperfections ◽  
The Stability ◽  
Reticulated Shell Structure

Based on the probability reliability theory, this paper proposes a modified consistent mode imperfection method, which fits the integral stability analysis of single-layer reticulated shells with the initial geometric imperfections. Nearly 1000 elasto-plastic load-deflection overall processes of four different rise-to-span ratio for Kiewitt-8 single-layer reticulated shells are analyzed by using the random imperfection mode method, the consistent mode imperfection method and the modified consistent mode imperfection method respectively. The study shows that the random imperfection mode method can assess the influence of initial geometric imperfections on structure stability more scientifically, but the calculation is quite large. By using the consistent mode imperfection method, the buckling load is not sure to be the most unfavorable, and the degree of reliability couldnt be ensured effectively. The modified consistent mode imperfection method can gain the buckling load which meets the requirement of probability reliability with less calculation. It can also assess the stability performance of single-layer reticulated shell structure more reasonably and safely.

scholarly journals Some aspects of consideration of initial imperfections in the calculations of stability of thin-walled elements of open profile

2021 ◽  
pp. 122-128
Author(s):  
Ivan Okhten ◽  
Olha Lukianchenko
Keyword(s):  
Middle Surface ◽  
Stability Loss ◽  
Critical Force ◽  
The Finite Element Method ◽  
Geometric Imperfections ◽  
Initial Imperfections ◽  
General Stability ◽  
Initial Geometric Imperfections ◽  
Linear And Nonlinear ◽  
The Stability

Performed analysis of the initial geometric imperfections influence on the stability of the open C-shaped bars. Test tasks were solved in MSC Nastran, which is based on the finite element method. Imperfections are given in different formulations: the general stability loss of an ideal bar, of wavy bulging of walls and shelves, of deplanation of a bar. To model imperfections, has been developed a program which for the formation of new coordinates of the nodes of the "deformed" model, the components of a vector similar to the form of stability loss are added to the corresponding coordinates of the middle surface of the bar. In this way, you can set initial imperfections in the forms of stability loss of the bar with different amplitude. Researches made with different values of the imperfection amplitude and eccentricity of applied efforts. All tasks are performed in linear and nonlinear staging. The conclusion is made regarding the influence of initial imperfections form and imperfection amplitude on the critical force in nonlinear calculations. It was found that the most affected are imperfections, which are given in the form of total loss of stability. It was revealed the influence of the imperfection amplitude on the magnitude of the critical force for such imperfections. The influence of imperfections amplitude given in the form of wavy bulging walls and in the form of deplanations is not affected on the value of the critical force.

Appraisal of Allowable Loads by Simplified Rules

1986 ◽  
Vol 108 (2) ◽  
pp. 131-137
Author(s):  
D. Moulin
Keyword(s):  
Experimental Investigation ◽  
Plastic Region ◽  
Thin Structures ◽  
Geometric Imperfections ◽  
Buckling Behavior ◽  
Simplified Method ◽  
Post Buckling ◽  
Initial Geometric Imperfections ◽  
Fast Breeder Reactors ◽  
Breeder Reactors

This paper presents a simplified method to analyze the buckling of thin structures like those of Liquid Metal Fast Breeder Reactors (LMFBR). The method is very similar to those used for the buckling of beams and columns with initial geometric imperfections, buckling in the plastic region. Special attention is paid to the strain hardening of material involved and to possible unstable post-buckling behavior. The analytical method uses elastic calculations and diagrams that account for various initial geometric defects. An application of the method is given. A comparison is made with an experimental investigation concerning a representative LMFBR component.

Evaluation of Compressive Strengths of HPS Plate Systems Stiffened with Trapezoidal Stiffeners

2013 ◽  
Vol 671-674 ◽  
pp. 1025-1028
Author(s):  
Dong Ku Shin ◽  
Kyungsik Kim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Performance ◽  
Nonlinear Finite Element ◽  
Linear Strain ◽  
Element Analysis ◽  
Geometric Imperfections ◽  
Eurocode 3 ◽  
Initial Geometric Imperfections ◽  
Plate System

The ultimate compressive strengths of high performance steel (HPS) plate system stiffened longitudinally by closed stiffeners have been investigated by the nonlinear finite element analysis. Both conventional and high performance steels were considered in models following multi-linear strain hardening constitutive relationships. Initial geometric imperfections and residual stresses were also incorporated in the analysis. Numerical results have been compared to compressive strengths from Eurocode 3 EN 1993-1-5 and FHWA-TS-80-205. It has been found that although use of Eurocode 3 EN 1993-1-5 and FHWA-TS-80-205 may lead to highly conservative design strengths when very large column slenderness parameters are encountered

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