The Doubly Nonlinear Limit Load Analysis of Space Grid Structure

2012 ◽  
Vol 166-169 ◽  
pp. 144-149
Author(s):  
Cao Xi ◽  
Yun Hong Hao
Keyword(s):  
Limit Load ◽  
Grid Structure ◽  
Limit Loads ◽  
Load Increment ◽  
Mechanics Model ◽  
Space Grid ◽  
Calculated Load ◽  
Doubly Nonlinear ◽  
Load Analysis ◽  
Complementary Equation

This paper first adopts variational inequation—the method of linear complementary equation. We use this method to analyses the elastoplastic limit load of space grid structure. This is a way to resolve the nonlinear question. Adopting this method to resolve the limit load of space grid structure avoid some drawback caused by adopting iteration method. We only need do some limited compute to a load-increment then we can obtain consequence, which fit in with all condition. Particularly, though adopting the method of linear complementary equation, we can control the value of limit load, make the calculated load can not exceed the limit load. Once exceeding, computer can decrease load- increment automatically and load again till getting the limit load of structure. Based on elastoplastic limit load analysis, this paper has considered big deformation impact on the limit load of bspace grid structure. We have made analysis of doubly nonlinear limit loads under the condition of coupling out of elastoplastic big deformation. The method and theory of this paper can combine with all kinds of single rod mechanics model.

Limit Load Analysis of Crack Contained Thick Walled Cylinders

2010 ◽  
Author(s):  
Saeid Hadidi-Moud ◽  
David John Smith
Keyword(s):  
Plastic Deformation ◽  
Limit State ◽  
Limit Load ◽  
Combined Loading ◽  
Finite Element Analyses ◽  
Limit Loads ◽  
Integrity Assessment ◽  
Crack Configuration ◽  
Load Analysis

Reliable limit load estimations for thick walled pressurized cylinders containing defects are required for the assessment of integrity of structures that experience significant plastic deformation prior to failure. Analytical and finite element analyses of limit load in thick walled cylinders containing defects are presented in this paper. FE analyses were conducted to obtain estimates of the limit state of loading for a range of combined loading schemes and loading sequences for open-end and closed-end cylinder. Part through shallow and deep hoop cracks in the cylinder for uniform radial, uniform axial and combined loading were examined. The results suggest that adjustments to the estimates of limit loads obtained from conventional methods reported in literature are needed in order to reflect the role of material response, crack configuration and boundary conditions on the limit loads of defected thick walled pipes and cylinders. These findings are very important and should be noted carefully, especially in the context of treatment of hoop and axial residual stresses in the integrity assessment of pipelines containing part through cracks.

scholarly journals Inf–sup conditions on convex cones and applications to limit load analysis

2019 ◽  
Vol 24 (10) ◽  
pp. 3331-3353 ◽  
Author(s):  
Jaroslav Haslinger ◽  
Stanislav Sysala ◽  
Sergey Repin
Keyword(s):  
Yield Criterion ◽  
Failure Mechanisms ◽  
Limit Load ◽  
Convex Cones ◽  
Mesh Adaptivity ◽  
Limit Loads ◽  
Perfectly Plastic ◽  
Dual Cones ◽  
Geotechnical Stability ◽  
Load Analysis

The paper is devoted to a family of specific inf–sup conditions generated by tensor-valued functions on convex cones. First, we discuss the validity of such conditions and estimate the value of the respective constant. Then, the results are used to derive estimates of the distance to dual cones, which are required in the analysis of limit loads of perfectly plastic structures. The equivalence between the static and kinematic approaches to limit analysis is proven and computable majorants of the limit load are derived. Particular interest is paid to the Drucker–Prager yield criterion. The last section exposes a collection of numerical examples including basic geotechnical stability problems. The majorants of the limit load are computed and expected failure mechanisms of structures are visualized using local mesh adaptivity.

Local Limit-Load Analysis Using the mβ Method

2006 ◽  
Vol 129 (2) ◽  
pp. 296-305 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Lower Bound ◽  
Upper Bound ◽  
Local Limit ◽  
Limit Load ◽  
Element Analysis ◽  
Limit Loads ◽  
Linear Elastic ◽  
Reference Volume ◽  
Component Design ◽  
Load Analysis

Several upper-bound limit-load multipliers based on elastic modulus adjustment procedures converge to the lowest upper-bound value after several linear elastic iterations. However, pressure component design requires the use of lower-bound multipliers. Local limit loads are obtained in this paper by invoking the concept of “reference volume” in conjunction with the mβ multiplier method. The lower-bound limit loads obtained compare well to inelastic finite element analysis results for several pressure component configurations.

Pressure-Plus-Moment Limit-Load Analysis for a Cylindrical Shell Nozzle

1987 ◽  
Vol 109 (3) ◽  
pp. 297-301 ◽  
Author(s):  
C. J. Tabone ◽  
R. H. Mallett
Keyword(s):  
Cylindrical Shell ◽  
Three Dimensional ◽  
Limit Load ◽  
Element Model ◽  
Combined Loading ◽  
Inelastic Behavior ◽  
Limit Loads ◽  
Out Of Plane ◽  
Load Analysis ◽  
The Moment

A finite element model of a nozzle in a cylindrical shell is analyzed for three cases; pressure, out-of-plane moment and combined pressure plus out-of-plane moment. The model uses three-dimensional finite elements and the analysis considers inelastic behavior at small displacements. Load versus displacement behavior is given for the three cases. Estimates of limit loads are obtained based upon extrapolation of load versus inverse displacement data curves. An interaction expression is used to show the effect of the combined loading for a case in which an internal pressure reduces the moment capability of the nozzle by 35 percent.

Limit Load Analysis of Pipe Bend With Extrados Wall Thinning

2014 ◽  
Author(s):  
TaeRyong Kim ◽  
ChangKyun Oh
Keyword(s):  
Internal Pressure ◽  
Bending Moment ◽  
Limit Load ◽  
Plastic Limit ◽  
Pipe Bend ◽  
Limit Loads ◽  
Wall Thinning ◽  
Piping Systems ◽  
Load Analysis ◽  
The Difference

Since pipe bend has a characteristic that extrados becomes thinner and intrados thicker after fabrication process, it can be expected to be vulnerable to extrados wall thinning due to corrosion or erosion during its operation. In this paper, limit loads of pipe bend with the thinning are computed under the loading conditions of internal pressure and bending moment. Several case studies with varying geometries and wall thinning shapes are presented. The difference in the limit loads behavior between pipe bend and welded elbow is also reviewed. The calculated plastic limit loads of pipe bend are compared with other research results for the welded elbow. The results show that pipe bend can be applied to safety-related piping systems as far as the internal pressure and bending moment only are considered.

Incorporation of Strain Hardening Effect Into Limit Load Analysis

2010 ◽  
Author(s):  
P. S. Reddy Gudimetla ◽  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Strain Hardening ◽  
Limit Load ◽  
Active Volume ◽  
Limit Loads ◽  
Reference Volume ◽  
Perfectly Plastic ◽  
Tangent Method ◽  
Novel Method ◽  
Typical Strain ◽  
Load Analysis

In this paper a novel method for finding out limit loads in the components or structures by incorporating strain hardening effects is presented. This has been done by including certain amount of the strain hardening into limit load analysis, which normally idealizes the material to be perfectly plastic. The typical strain hardening curves including bilinear hardening and Ramberg-Osgood material models are investigated. The paper also concentrates on plastic reference volume correction concept to find the active volume participating in plastic collapse. The reference volume concept in combination with mα-Tangent method is used to estimate the lower bound limit load of different components.

The Seismic Damage Investigation and Phenomenon Analysis of Space Grid Structures in Lushan Ms 7.0 Earthquake

2014 ◽  
Vol 501-504 ◽  
pp. 1535-1541 ◽  
Author(s):  
Jue Hui Xing ◽  
Ming Lu ◽  
Hai Wang Li ◽  
Ya Min Zhao ◽  
Yan Yu
Keyword(s):  
Seismic Design ◽  
Shell Structure ◽  
Historical Earthquakes ◽  
Seismic Damage ◽  
Grid Structure ◽  
Paper Briefly ◽  
Space Grid ◽  
Reticulated Shell Structure ◽  
Ball Joints ◽  
Damage Investigation

People remained optimistic about the safety of the space grid structures, because the seismic damages of space grid structures were quite rare and rather light. However, two space grid structures got damaged in 2013 Lushan Ms 7.0 earthquake. The two structures are the double-layer reticulated shell structure and flatbed grid structure, namely Lushan Gymnasium and Lushan Middle School Gymnasium respectively. This paper briefly reviews the seismic damage phenomena of grid structures in historical earthquakes, and then focuses on the two damaged space grid structures in Lushan earthquake. The reason why the two space grid structures got damaged are derived from the force state analysis of the rods, ball joints and bearings. Finally, we come up with the effective advice for the seismic design and construction of the space grid structure.

Limit Load Analysis of Cracked Components Using the Reference Volume Method

2006 ◽  
Vol 129 (3) ◽  
pp. 391-399 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Elastic Modulus ◽  
Three Dimensional ◽  
Local Limit ◽  
Limit Load ◽  
Multiple Cracks ◽  
Element Analysis ◽  
Limit Loads ◽  
Integrity Assessment ◽  
Reference Volume ◽  
Volume Method

Cracks and flaws occur in mechanical components and structures, and can lead to catastrophic failures. Therefore, integrity assessment of components with defects is carried out. This paper describes the Elastic Modulus Adjustment Procedures (EMAP) employed herein to determine the limit load of components with cracks or crack-like flaw. On the basis of linear elastic Finite Element Analysis (FEA), by specifying spatial variations in the elastic modulus, numerous sets of statically admissible and kinematically admissible distributions can be generated, to obtain lower and upper bounds limit loads. Due to the expected local plastic collapse, the reference volume concept is applied to identify the kinematically active and dead zones in the component. The Reference Volume Method is shown to yield a more accurate prediction of local limit loads. The limit load values are then compared with results obtained from inelastic FEA. The procedures are applied to a practical component with crack in order to verify their effectiveness in analyzing crack geometries. The analysis is then directed to geometries containing multiple cracks and three-dimensional defect in pressurized components.

Limit Loads for Laterally Loaded I-Section Beams With Consideration of Shear

2003 ◽  
Vol 47 (02) ◽  
pp. 83-91
Author(s):  
L. Belenkiy ◽  
Y. Raskin
Keyword(s):  
Physical Model ◽  
Limit Load ◽  
Nonlinear Finite Element ◽  
Shear Forces ◽  
Element Analysis ◽  
Limit Loads ◽  
Closed Form Solutions ◽  
Engineering Technique ◽  
Laterally Loaded ◽  
The Web

The paper examines an effect of shear forces on limit load for I-section beams carrying later alloads. The problem is solve don the basis of a physical model, which enables one to take into account the effect of a resistance of beam flanges to the plastic shears train in the web of the beam. The physical model for the evaluation of limit loads was veriŽed using nonlinear finite element analysis. An engineering technique for the calculation of limit loads for shiphull beams subjected to large shear forces was developed using this model. As illustrative examples, the paper shows the application of the proposed technique to obtain closed-form solutions for the prediction of limit loads.

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