scholarly journals On the Adequacy of Shell Models for Predicting Stresses and Strains in Thick-Walled Tubes Subjected to Detonation Loading

2013 ◽  
Author(s):  
Neal P. Bitter ◽  
Joseph E. Shepherd
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Shell Model ◽  
Wall Thickness ◽  
Axial Strain ◽  
Nonlinear Behavior ◽  
Element Model ◽  
Shell Models ◽  
Axial Curvature ◽  
Detonation Loading

This paper analyzes the adequacy of shell models for predicting stresses and strains in thick-walled tubes subjected to detonation loads. Of particular interest are the large axial strains which are produced at the inner and outer surfaces of the tube due to bending along the tube axis. First, comparisons between simple shell theory and a static finite element model are used to show that the axial strain varies proportionally with wall thickness and inversely with the square of the axial wavelength. For small wavelengths, this comparison demonstrates nonlinear behavior and a breakdown of the shell model. Second, a dynamic finite element model is used to evaluate the performance of transient shell equations. This comparison is used to quantify the error of the shell model with increasing wall thickness and show that shell models can be inaccurate near the load front where the axial curvature is high. Finally, the results of these analyses are used to show that the large axial strains which are sometimes observed in experiments cannot be attributed to through-wall bending and appear to be caused instead by non-ideal conditions present in the experiments.

scholarly journals Modeling the flexural behavior of corroded reinforced concrete beams with considering stirrups corrosion

2020 ◽  
Vol 14 (3) ◽  
pp. 26-39
Author(s):  
Nguyen Ngoc Tan ◽  
Nguyen Trung Kien
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Finite Element Model ◽  
Limit State ◽  
Nonlinear Behavior ◽  
Element Model ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Bending Test ◽  
Fe Model

The reinforcement corrosion is one of the most dominant deterioration mechanisms of existing reinforced concrete structures. In this paper, the effects of the stirrup corrosion on the structural performance of five corroded beams have been simulated using the finite element model with DIANA software. These tested beams are divided into two groups for considering different inputs: (i) without corroded stirrups in flexural span, (ii) with locally corroded stirrups at different locations (e.g. full span, shear span, middle span). FE model has been calibrated with experimental results that were obtained from the four-point bending test carried out on the tested beams. This study shows that the stirrups corrosion should be received more attention in the serviceability limit state since its considerable effect on flexural behavior. Based on a parametric study, it shows that the effect of the cross-section loss of tension reinforcements on the load-carrying capacity of the corroded beam is more significant than the bond strength reduction. Keywords: reinforced concrete; beam; stirrup corrosion; finite element model; flexural nonlinear behavior.

scholarly journals Numerical Simulation and Experimental Study On Non-Axisymmetric Spinning With a Groove At The Middle of The Tube

2022 ◽  
Author(s):  
Zhen Jia ◽  
Xuan Wang ◽  
Yongping Shen ◽  
Yilian Xie ◽  
Xue Gong ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Wall Thickness ◽  
Element Model ◽  
Maximum Deviation ◽  
3D Finite Element ◽  
Transition Zones ◽  
3D Finite Element Model ◽  
Roller Path ◽  
Increasing Demand

Abstract Spinning is widely used in aerospace and automobile industries, and non-axisymmetric spinning is developing with the increasing demand of irregular shape forming. Based on this, an avoidance groove at the middle of the tube (AGMT) which has potential application value in aircraft structure weight reduction is proposed and formed by using non-axisymmetric die-less spinning. The roller path is analyzed. The relationship between radial displacement of roller and the rotation angle of the tube is deduced. Based on the roller path, 3D finite element model is established. Then, the AGMT spinning experiment is carried out to verify the simulation results. The maximum deviation between the simulation and experimental results is less than 15%. It is indicated that the 3D finite element model established in this study is reliable and the method for the AGMT forming is feasible. The wall thickness and strain-stress distributions are analyzed. The severe wall thicken and thinning occur in the transition zones, so more attention should be paid to these positions. The depth of the groove has great impact on the forming quality. Deeper groove results in distortion and larger wall thickness difference. The research laid a foundation for the further development and optimization of the AGMT spinning.

Helical Wire Behavior of Unbonded Flexible Pipes Under Bending

2015 ◽  
Author(s):  
Yutian Lu ◽  
Huibin Yan ◽  
Yong Bai ◽  
Peng Cheng
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Axial Strain ◽  
Bending Moment ◽  
Element Model ◽  
Flexible Pipe ◽  
Slip Mechanism ◽  
Flexible Pipes ◽  
Bending Behavior ◽  
Unbonded Flexible Pipes

The bending behavior of unbonded flexible pipe is governed by the response of the helical wires in the tensile armor to bending. The behavior of the helical wire, especially the axial strain, is influenced by the slip mechanism as a result of an increasing curvature under bending. In the present paper, two limit curves are considered with a certain curvature. A 3-D finite element model using ABAQUS is developed to simulate the practical behavior of the helical wires under bending. By comparing the FEA and theoretical results, a basic conclusion about the real slip path of the helical wire between two limit curves is introduced. A hysteretic bending moment-curvature relationship induced by the slip mechanism is obtained from the finite element model as well.

scholarly journals Nonlinear joint model updating using static responses

2016 ◽  
Vol 8 (12) ◽  
pp. 168781401668265 ◽  
Author(s):  
Ping-Ping Yuan ◽  
Zuo-Cai Wang ◽  
Wei-Xin Ren ◽  
Xia Yang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Objective Function ◽  
Model Updating ◽  
Nonlinear Behavior ◽  
Element Model ◽  
Joint Model ◽  
Joint System ◽  
Structural Joint ◽  
Nonlinear Joint

Nonlinear behavior is often observed in structural joint system due to external loads. A new technique of nonlinear structural joint model updating with static load test results is proposed in this article to investigate the actual behavior of a joint system. To calibrate the nonlinear parameters of the structural joint system, an appropriate finite element model is first established to characterize the complex nonlinear behavior caused by the joint connections. Combined with the sensitivity analysis, the parameters that describe the nonlinear behavior of the joint connections are selected as the parameters to be updated. Subsequently, an objective function is created in accordance with the residual between experimentally measured static deflections and analytically calculated static deflections through finite element model. The objective function is then optimized to obtain the proper values of the nonlinear force–displacement parameters with the regular simulated annealing algorithm. To validate the efficiency of this updating approach, two numerical examples under static concentrated loads are conducted. The obtained results indicate that the nonlinear joint model parameters can be successfully updated, and the updated new model can further forecast the true deflections of the nonlinear structure with good accuracy and stability.

Influences of Blank Holding Force on Stamping of Large Ellipsoidal Heads Based on Simulation

2012 ◽  
Vol 217-219 ◽  
pp. 2097-2100 ◽  
Author(s):  
Zheng Zhi Luo ◽  
Jing Zeng ◽  
Jin Peng Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Wall Thickness ◽  
Computational Efficiency ◽  
Adaptive Mesh ◽  
Element Model ◽  
Experimental Results ◽  
Forming Quality ◽  
Sheet Stamping ◽  
Blank Holding Force

Ellipsoidal heads is a important composition of railways tank car. Sheet stamping process is a common method used for manufacturing ellipsoidal heads. An accurate and efficient finite element model was developed for analysis and prediction of ellipsoidal heads forming quality, with different degrees of reduction deformation at different binder forces considered, and self-adaptive mesh were adopted to improve computational efficiency and quality. And the results of simulation was validated by experimental results. Based on this finite element model, the distributions of stress, strain and wall thickness during this process were obtained.

Full Scale Blasting Test and Finite Element Analysis of Nozzle Repair Pipeline

2017 ◽  
Author(s):  
Xu Wu ◽  
Jian Shuai
Keyword(s):  
Finite Element ◽  
Wall Thickness ◽  
Oil And Gas ◽  
Axial Strain ◽  
Element Model ◽  
Nozzle Diameter ◽  
Gas Pipelines ◽  
Axial Deformation ◽  
Element Analysis ◽  
Oil And Gas Pipelines

Nozzle repair is one of the common repair methods for oil and gas pipelines. As a means to test the applicability of the pipeline, the pressure test is widely used in the integrity evaluation of oil and gas pipelines. To avoid possible failure accidents of nozzle repair pipeline, hydrostatic burst tests were performed. The finite element model of the pipeline was established. The effects of nozzle diameter and nozzle wall thickness parameters on the stress-strain response of the nozzle repair pipeline were discussed. The results show that the yield stress of the specimen is about 11.2MPa, and the blasting pressure is 12.9MPa. Due to the effect of nozzle structure, the change of strain for each point with the internal pressure is inconsistent. The ratio of axial strain to circumferential strain decreases with the increase of pressure, which shows that the yield mainly occurs in the hoop direction, and the axial deformation increases with the increase of the pressure. Under the condition of the_constant wall thickness, the stress distribution of pipeline is uniform and the yield pressure increases with the decrease of nozzle diameter. The smaller the nozzle diameter, the better the bearing capacity. The selection for the wall thickness of nozzle should be greater than or equal to the thickness of the pipe wall.

Influence by Casing Geometric Imperfection on Anti-Collapse Strength with Finite Element Calculation

2012 ◽  
Vol 268-270 ◽  
pp. 1114-1118
Author(s):  
Ji Jun Xue ◽  
Peng Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Wall Thickness ◽  
Element Model ◽  
Element Calculation ◽  
Geometric Imperfection ◽  
Thickness Increase ◽  
Collapse Strength ◽  
Wall Thickness Increase ◽  
Better Than

This essay was to build a finite element model to find the influence by oil casing geometric imperfection on anti-collapse strength. Two types of oil casing, Ф177.8×10.36mm/P110 andФ127×9.19mm/ P110, was taken for the calculation, considering the influence on anti-collapse strength by casing with two elements separately, ovality and non-uniformity of wall thickness. The calculation show that the anti-collapse strength of perfect casing perform better than that of imperfect casing. Ovality is an important factor for the anti-collapse strength, and the anti-collapse strength decrease rapidly as the ovality increase. Non-uniformity of wall thickness is the less important factor for anti-collapse strength, and the anti-collapse strength decrease slightly and slowly while the non-uniformity of wall thickness increase.

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