A Plane Stress Model to Predict Angular Distortion in Single Pass Butt Welded Plates With Weld Reinforcement

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Junqiang Wang ◽  
Jianmin Han ◽  
Joseph P. Domblesky ◽  
Zhiqiang Li ◽  
Yingxin Zhao ◽  
...  
Keyword(s):  
Plane Stress ◽  
Three Dimensional ◽  
Angular Distortion ◽  
Computational Time ◽  
Fe Model ◽  
Stress Model ◽  
Contraction Force ◽  
Computational Costs ◽  
Linear Elastic ◽  
Steel Liner

While coupled three-dimensional (3D) nonisothermal finite-element (FE) models can be used to predict distortion in weldments, computational costs remain high, and the development of alternate FE-based engineering approaches remains an important topic. In the present study, a plane stress model is proposed for analyzing angular distortion in butt-welded plates having appreciable levels of weld reinforcement. The approach is based on an analysis of contractile shrinkage forces and only requires knowledge of the plastic zone geometry to develop the input data needed for an isothermal linear elastic FE model. Results show that the proposed method significantly reduces the computational time and provides acceptable accuracy when plane stress conditions are satisfied. The effect of weld reinforcement was also analyzed using the method. The results indicate that the contraction force from the bead is dominant, and that the primary effect of the crown is to increase eccentricity of the in-plane contraction force. A steel liner from a nuclear plant cooling tower was also analyzed to demonstrate the method. The results showed that the model was able to predict the distortion pattern and demonstrated fair accuracy.

Predicting Distortion in Butt Welded Plates Using an Equivalent Plane Stress Representation Based on Inherent Shrinkage Volume

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Junqiang Wang ◽  
Jianmin Han ◽  
Joseph P. Domblesky ◽  
Weijing Li ◽  
Zhiyong Yang ◽  
...  
Keyword(s):  
Plane Stress ◽  
Good Accuracy ◽  
Three Dimensional ◽  
Fe Model ◽  
Isothermal Model ◽  
Dimensional Changes ◽  
Plastic Shrinkage ◽  
Large Structures ◽  
Stress Representation ◽  
Fabrication Costs

Due to the adverse effect that distortion has on assembly fit-up and fabrication costs in welded structures, the ability to predict dimensional changes represents an important engineering concern. While distortion can be analyzed using a full three-dimensional (3D) finite element (FE) model, this often proves to be computationally expensive for medium and large structures. In comparison, a two-dimensional (2D) FE model can significantly reduce the time and effort needed to analyze distortion though such analyses often have reduced accuracy. To address these issues, a 3D plane stress model using shell meshes based on the shrinkage volume approach is proposed. By inversing the plastic shrinkage zone geometry, an eccentric loading condition and equivalent plane stress representation can be developed and used to predict distortion in butt welded plates using an isothermal model. The model was validated using deflection data from welded plates and found to provide good accuracy over the range of thicknesses considered. Results obtained from welding of a large containment tank are also presented and further confirm the utility of the method.

Fitness for Purpose Assessment of 8” Diameter WAGI Gate Valves for Operation at an Uprated Pressure

2008 ◽  
Author(s):  
Paul Cousens ◽  
Chas Jandu ◽  
Antony Francis
Keyword(s):  
Failure Modes ◽  
Three Dimensional ◽  
General Purpose ◽  
Fe Model ◽  
Plastic Collapse ◽  
Potential Hazard ◽  
Operating Pressure ◽  
Fitness For Purpose ◽  
Linear Elastic ◽  
Increased Pressure

When considering strength parameters, the selection of a valve for a particular application is generally based on the ‘Class Rating’, i.e. the valve thickness is suitable for a given temperature and pressure for a given material. A Liquefied Natural Gas (LNG) station operator identified three Class 600, bolted-bonnet gate valves, operating at cryogenic temperatures, as having pressure relief set-points approximately 7 barg below the 99 barg operating pressure of the process lines on which they were located. This lower set-point impeded the productivity of the lines and also presented a potential hazard from the vented gas. Therefore, to avoid venting, it was requested by the asset owner to determine whether the relief set-points on the gate valves could be safely increased to that of the process lines, without affecting the integrity of the valves. This paper presents how the stresses in the valve bodies were determined by creating a three-dimensional solid Finite Element (FE) model of the valves and adjacent pipework using PATRAN [5] with subsequent linear elastic analyses being undertaken using the general purpose FE code ABAQUS [6] for all loading scenarios. A detailed description of the subsequent fitness-for-purpose assessment to the requirements of PD5500 [10] for operating at the increased pressure is also presented considering the following failure modes; plastic collapse, incremental plastic collapse and fatigue. The results of the fitness-for-purpose assessment of the valves demonstrate that the valves will not fail by general plastic collapse, local plastic collapse or incremental plastic collapse at the increased pressure and that they are acceptable for the proposed fatigue duty. Based on the results of the work presented, and a separate functionality check by the asset owner, the set-points on the gate valves were subsequently increased to the desired level.

scholarly journals A Proof-of-Concept Algorithm for the Retrieval of Total Column Amount of Trace Gases in a Multi-Dimensional Atmosphere

2021 ◽  
Vol 13 (2) ◽  
pp. 270
Author(s):  
Adrian Doicu ◽  
Dmitry S. Efremenko ◽  
Thomas Trautmann
Keyword(s):  
Trace Gases ◽  
Three Dimensional ◽  
Principal Component ◽  
Radiative Transfer Model ◽  
Computational Time ◽  
Transfer Model ◽  
Proof Of Concept ◽  
Discrete Ordinate ◽  
Distribution Method ◽  
Total Column

An algorithm for the retrieval of total column amount of trace gases in a multi-dimensional atmosphere is designed. The algorithm uses (i) certain differential radiance models with internal and external closures as inversion models, (ii) the iteratively regularized Gauss–Newton method as a regularization tool, and (iii) the spherical harmonics discrete ordinate method (SHDOM) as linearized radiative transfer model. For efficiency reasons, SHDOM is equipped with a spectral acceleration approach that combines the correlated k-distribution method with the principal component analysis. The algorithm is used to retrieve the total column amount of nitrogen for two- and three-dimensional cloudy scenes. Although for three-dimensional geometries, the computational time is high, the main concepts of the algorithm are correct and the retrieval results are accurate.

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

scholarly journals Estimation of 6D Object Pose Using a 2D Bounding Box

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 2939
Author(s):  
Yong Hong ◽  
Jin Liu ◽  
Zahid Jahangir ◽  
Sheng He ◽  
Qing Zhang
Keyword(s):  
Neural Network ◽  
Loss Function ◽  
Three Dimensional ◽  
Unit Vector ◽  
Prediction Algorithm ◽  
Computational Time ◽  
Bounding Box ◽  
Dimensional Unit ◽  
Bounding Boxes ◽  
Rgb Image

This paper provides an efficient way of addressing the problem of detecting or estimating the 6-Dimensional (6D) pose of objects from an RGB image. A quaternion is used to define an object′s three-dimensional pose, but the pose represented by q and the pose represented by -q are equivalent, and the L2 loss between them is very large. Therefore, we define a new quaternion pose loss function to solve this problem. Based on this, we designed a new convolutional neural network named Q-Net to estimate an object’s pose. Considering that the quaternion′s output is a unit vector, a normalization layer is added in Q-Net to hold the output of pose on a four-dimensional unit sphere. We propose a new algorithm, called the Bounding Box Equation, to obtain 3D translation quickly and effectively from 2D bounding boxes. The algorithm uses an entirely new way of assessing the 3D rotation (R) and 3D translation rotation (t) in only one RGB image. This method can upgrade any traditional 2D-box prediction algorithm to a 3D prediction model. We evaluated our model using the LineMod dataset, and experiments have shown that our methodology is more acceptable and efficient in terms of L2 loss and computational time.

scholarly journals Numerical Analysis of the Perforated Steel Sheets Under Uni-Axial Tensile Force

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 632 ◽  
Author(s):  
Ahmed M. Sayed
Keyword(s):  
Load Capacity ◽  
Tensile Force ◽  
Three Dimensional ◽  
Tensile Load ◽  
Experimental Tests ◽  
Strain Engineering ◽  
Uniaxial Tensile ◽  
Fe Model ◽  
Stress Strain ◽  
Steel Sheets

The perforated steel sheets have many uses, so they should be studied under the influence of the uniaxial tensile load. The presence of these holes in the steel sheets certainly affects the mechanical properties. This paper aims at studying the behavior of the stress-strain engineering relationships of the perforated steel sheets. To achieve this, the three-dimensional finite element (FE) model is mainly designed to investigate the effect of this condition. Experimental tests were carried out on solid specimens to be used in the test of model accuracy of the FE simulation. Simulation testing shows that the FE modeling revealed the ability to calculate the stress-strain engineering relationships of perforated steel sheets. It can be concluded that the effect of a perforated rhombus shape is greater than the others, and perforated square shape has no effect on the stress-strain engineering relationships. The efficiency of the perforated staggered or linearly distribution shapes with the actual net area on the applied loads has the opposite effect, as it reduces the load capacity for all types of perforated shapes. Despite the decrease in load capacity, it improves the properties of the steel sheets.

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