Combining Variation Simulation With Welding Simulation for Prediction of Deformation and Variation of a Final Assembly

2012 ◽  
Vol 12 (2) ◽  
Author(s):  
Andreas Pahkamaa ◽  
Kristina Wärmefjord ◽  
Lennart Karlsson ◽  
Rikard Söderberg ◽  
John Goldak
Keyword(s):  
Final Outcome ◽  
Positioning Error ◽  
Welding Simulation ◽  
Rotation Matrices ◽  
Heating And Cooling ◽  
Final Assembly ◽  
Geometric Tolerances ◽  
The Difference ◽  
Variation Simulation ◽  
Different Sources

In most variation simulations, i.e., simulations of geometric variations in assemblies, the influence from heating and cooling processes, generated when two parts are welded together, is not taken into consideration. In most welding simulations, the influence from geometric tolerances on parts is not taken into consideration, i.e., the simulations are based on nominal parts. In this paper, these two aspects, both crucial for predicting the final outcome of an assembly, are combined. Monte Carlo simulation is used to generate a number of different non-nominal parts in a software for variation simulation. The translation and rotation matrices, representing the deviations from the nominal geometry due to positioning error, are exported to a software for welding simulation, where the effects from welding are applied. The final results are then analyzed with respect to both deviation and variation. The method is applied on a simple case, a T-weld joint, with available measurements of residual stresses and deformations. The effect of the different sources of deviation on the final outcome is analyzed and the difference between welding simulations applied to nominal parts and to disturbed (non-nominal) parts is investigated. The study shows that, in order to achieve realistic results, variation simulations should be combined with welding simulations. It does also show that welding simulations should be applied to a set of non-nominal parts since the difference between deviation of a nominal part and deviation of a non-nominal part due to influence of welding can be quite large.

scholarly journals Combining Variation Simulation With Welding Simulation for Prediction of Deformation

2010 ◽  
Author(s):  
Andreas Pahkamaa ◽  
Kristina Wa¨rmefjord ◽  
Lennart Karlsson ◽  
Rikard So¨derberg ◽  
John Goldak
Keyword(s):  
Simulation Software ◽  
Final Outcome ◽  
Welding Simulation ◽  
Rotation Matrices ◽  
Heating And Cooling ◽  
Geometric Tolerances ◽  
Software Packages ◽  
The Difference ◽  
Variation Simulation ◽  
Different Sources

In most variation simulations, i.e. simulations of geometric variations in assemblies, the influence from the heating and cooling processes, generated when two parts are welded together, is not taken into consideration. In most welding simulations the influence from geometric tolerances on parts is not taken into consideration, i.e. the simulations are based on nominal parts. In this paper these two aspects, both crucial for predicting the final outcome of an assembly, are combined by linking two commercial software packages for variation simulation and for welding simulation together. Monte Carlo simulation is used to generate a number of different non-nominal parts in the variation simulation software. The translation and rotation matrices, representing the deviations from the nominal geometry due to positioning error, are exported to the welding simulation software, where the effects from welding are applied. Thereafter, the results from the welding simulation are exported back to the variation simulation software in order to compute and illustrate the deviations and variations of the final subassembly. The method is applied on a simple case, a T-weld joint, with available measurements of residual stresses and deformations. The effect of the different sources of deviation on the final outcome is analyzed and the difference between welding simulations applied to nominal parts and to disturbed parts is investigated.

An Approach to Variation Simulation of Final Aircraft Assembly with Presence of Sealant

2021 ◽  
pp. 1-22
Author(s):  
Artem Eliseev ◽  
Sergey Lupuleac ◽  
Boris Grigor'ev ◽  
Julia Shinder
Keyword(s):  
Numerical Test ◽  
Assembly Quality ◽  
Final Assembly ◽  
Static Condensation ◽  
Determining Factors ◽  
The Difference ◽  
Structural Parts ◽  
Structure Assembly ◽  
Variation Simulation ◽  
Aircraft Panels

Abstract The article discusses the process of aeronautical structure assembly in the presence of a sealant between the parts to be joined. An attempt to estimate the influence of sealant on assembly quality in terms of variation analysis is presented. The sealant is considered as a highly viscous liquid that is applied to the surfaces of the assembled parts before the start of final assembly. The modeling approach is based on simulation of two-way coupled fluid-structure interaction between fluid sealant and compliant structural parts. Reynolds lubrication approximation is used in the fluid dynamics problem and variational formulation of contact problem combined with static condensation is used in the structural one. The joining of two aircraft panels is used as a numerical test for demonstration of developed approach. Various phenomena connected with the presence of sealant are demonstrated. In particular, the difference in the fastener loosening due to sealant flow between different types of fasteners is investigated. Results of variation simulation show that presence of sealant should be considered among determining factors in the analysis of assembly quality.

Buildings

2017 ◽  
Author(s):  
Peter Rez
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Energy Efficient ◽  
Energy Use ◽  
Fossil Fuel ◽  
Local Climate ◽  
Heating And Cooling ◽  
The Difference ◽  
As If

Most of the energy used by buildings goes into heating and cooling. For small buildings, such as houses, heat transfer by conduction through the sides is as much as, if not greater than, the heat transfer from air exchanges with the outside. For large buildings, such as offices and factories, the greater volume-to-surface ratio means that air exchanges are more significant. Lights, people and equipment can make significant contributions. Since the energy used depends on the difference in temperature between the inside and the outside, local climate is the most important factor that determines energy use. If heating is required, it is usually more efficient to use a heat pump than to directly burn a fossil fuel. Using diffuse daylight is always more energy efficient than lighting up a room with artificial lights, although this will set a limit on the size of buildings.

scholarly journals Comparison of Building Simulation Methods for Modeling Apartment Balconies

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3955
Author(s):  
Yonghan Ahn ◽  
Hanbyeol Jang ◽  
Junghyon Mun
Keyword(s):  
Heat Transfer ◽  
Air Temperature ◽  
Parameter Analysis ◽  
Interior Space ◽  
Heating And Cooling ◽  
Significant Difference ◽  
Calculation Results ◽  
Infiltration Parameter ◽  
The Difference ◽  
Heating And Cooling Load

The purpose of this study is to compare the load calculation results by a model using the air changes per hour (ACH) method and a model using an airflow network (AFN) and to ascertain what causes the difference between the two models. In the basic case study, the difference in the heat transfer distribution of the model in the interior space was investigated. The most significant difference between the two models is the heat transfer that results from infiltration. Parameter analysis was performed to investigate the relationship between the difference and the environmental variables. The result shows that the greater the difference is between the air temperature inside the balcony and the outdoor air temperature, and the greater the air flows from the balcony to the residential area, and the greater the heating and cooling load difference occurs. The analysis using the actual weather files of five domestic cities in South Korea rather than a virtual case shows that the differences are not so obvious when the wind blows at a constant speed throughout the year, but are dominant when the wind does not blow during the night and is stronger alongside the occurrence of sunlight during the day.

scholarly journals 2. On the Polarizability of Heat from different Sources

1845 ◽  
Vol 1 ◽  
pp. 334-334
Author(s):  
Forbes
Keyword(s):  
Low Temperature ◽  
The Difference ◽  
Different Sources

The author of this paper states in it his belief, that the curious fact formerly announced to the Society of the greater permeability of mica, laminated by heat, to heat of low temperature, contrary to the usual character of the same substance (a property which he has since extended (see Proceedings, Jan. 1840) to changes of mechanical conditions of surface), may very probably explain, as M. Melloni anticipates, the difference in point of fact long contested between them as to the equal or unequal polarizability of heat from different sources.

scholarly journals Variation Simulation of Fixtured Assembly Processes for Compliant Structures Using Piecewise-Linear Analysis

2005 ◽  
Author(s):  
Michael L. Stewart ◽  
Kenneth W. Chase
Keyword(s):  
Piecewise Linear ◽  
Element Model ◽  
Linear Analysis ◽  
Elastic Analysis ◽  
Variation Analysis ◽  
Linear Elastic ◽  
Final Assembly ◽  
Compliant Part ◽  
Assembly Operations ◽  
Variation Simulation

While variation analysis methods for compliant assemblies are becoming established, there is still much to be done to model the effects of multi-step, fixtured assembly processes statistically. A new method is introduced for statistically analyzing compliant part assembly processes using fixtures. This method yields both a mean and a variant solution, which can characterize an entire population of assemblies. The method, called Piecewise-Linear Elastic Analysis, or PLEA, is developed for predicting the residual stress, deformation and springback variation resulting from fixtured assembly processes. A comprehensive, step-by-step analysis map is presented for introducing dimensional and surface variations into a finite element model, simulating assembly operations, and calculating the error in the final assembly. PLEA is validated on a simple, laboratory assembly and a more complex, production assembly. Significant modeling issues are resolved as well as the comparison of the analytical to physical results.

A Review of Maslahah Mursalah and Maqasid Shariah as Methods of Determining Islamic Legal Ruling

2021 ◽  
Vol 12 (3) ◽  
pp. 2994-3001
Author(s):  
Muhammad Nazir Alias Et.al
Keyword(s):  
Islamic Law ◽  
Legal Principles ◽  
Legal Principle ◽  
Difference Of Opinion ◽  
The Difference ◽  
Different Sources

The position of maqasid shariah as reference for Islamic legal ruling has been a source of dissenting opinions among contemporary ulama. Some of them accept maqasid shariah as a method of determining legal principles, whereas others do not. In classical usul fiqh literature, the discourse on maqasid shariah among the ulama only appears in discussions on the position of maslahah mursalah as a method of determining Islamic legal ruling. In light of this, the issue arises when the position of maqasid shariah, specifically as a source of law, is not mentioned by classical ulama. Therefore, a small number of scholars are of the view that maqasid Shariah is not clearly applied in the process of determining legal ruling, such as what had happened in the Shafie school of law. This article aims to review the concept of maslahah mursalah and maqasid shariah in the context of its status as a method of determining Islamic legal ruling. The findings of the study show that maslahah mursalah is not maqasid shariah because both of them originate from different sources. The rejection of maslahah mursalah by some ulama does not refer to maslahah that is in line with the higher objectives of Islamic law (maqasid shariah), but refers to maslahah that relies solely on logic and intellect. The difference of opinion among contemporary ulama regarding the position of maqasid shariah as a method of determining legal principle stems from confusion in defining and categorising maslahah mursalah and maqasid shariah.

Fast Precise Positioning of Circular Mark in Automatic Optical Inspection

2013 ◽  
Vol 325-326 ◽  
pp. 1614-1618
Author(s):  
Guang Jie Xiong ◽  
Yu Fei Liu ◽  
Rui Zhen Liu
Keyword(s):  
Printed Circuit Boards ◽  
Positioning Error ◽  
Circuit Boards ◽  
Precise Positioning ◽  
Automatic Optical Inspection ◽  
Running Time ◽  
Printed Circuit ◽  
Optical Inspection ◽  
Positioning Method ◽  
The Difference

Captured circular marks are deformed sometimes when Automatic Optical Inspection (AOI) is used to detect various defects on Printed Circuit Boards (PCB), which may affect the precision of inspection. A new accurate positioning method of circular marks is proposed to solve the problem by obtaining the center of the most round ellipse based on the criterion that the ratio of the difference between the length and width of its circumscribed rectangle and the width of the rectangle is less than 0.1. The simulation tests show that, if the mark has much more deformations, the center positioning error of the proposed algorithm is about 0.013 pixels, and the running time is less than 40ms. Therefore, the proposed method provides good characteristics such as speediness, strong anti-interference ability and robustness.

scholarly journals The Astrometric Possibilities of Very-Long-Baseline Interferometry

1986 ◽  
Vol 109 ◽  
pp. 143-155
Author(s):  
D. S. Robertson
Keyword(s):  
Plane Wave ◽  
Arrival Time ◽  
Very Long Baseline Interferometry ◽  
Radio Sources ◽  
Arrival Times ◽  
Long Baseline ◽  
The Difference ◽  
Different Sources

In the application of Very-Long-Baseline Interferometry (VLBI) to astrometric problems the fundamental observable is the difference in the arrival times of a wavefront at two widely separated receiving stations. Since the radio sources being observed are sufficiently distant that the arriving wavefront can be considered to be a plane wave, the differential arrival time is a measure of the component of the baseline in the direction of the source. Equivalently, if the baseline is known, the differential arrival time is sufficient to determine a circle on the sky containing the source. It is easy to show that a minimum of ten observations distributed among three different sources is sufficient to determine all of the source coordinates and the baseline coordinates simultaneously (Robertson, 1975).

scholarly journals Geo-Location Algorithm for Building Targets in Oblique Remote Sensing Images Based on Deep Learning and Height Estimation

2020 ◽  
Vol 12 (15) ◽  
pp. 2427
Author(s):  
Yiming Cai ◽  
Yalin Ding ◽  
Hongwen Zhang ◽  
Jihong Xiu ◽  
Zhiming Liu
Keyword(s):  
Remote Sensing ◽  
Simulation Analysis ◽  
Recognition Algorithm ◽  
Positioning Error ◽  
Remote Sensing Images ◽  
Target Height ◽  
Building Recognition ◽  
Aerial Remote Sensing ◽  
The Difference ◽  
Positioning Algorithm

To improve the accuracy of the geographic positioning of a single aerial remote sensing image, the height information of a building in the image must be considered. Oblique remote sensing images are essentially two-dimensional images and produce a large positioning error if a traditional positioning algorithm is used to locate the building directly. To address this problem, this study uses a convolutional neural network to automatically detect the location of buildings in remote sensing images. Moreover, it optimizes an automatic building recognition algorithm for oblique aerial remote sensing images based on You Only Look Once V4 (YOLO V4). This study also proposes a positioning algorithm for the building target, which uses the imaging angle to estimate the height of a building, and combines the spatial coordinate transformation matrix to calculate high-accuracy geo-location of target buildings. Simulation analysis shows that the traditional positioning algorithm inevitably leads to large errors in the positioning of building targets. When the target height is 50 m and the imaging angle is 70°, the positioning error is 114.89 m. Flight tests show that the algorithm established in this study can improve the positioning accuracy of building targets by approximately 20%–50% depending on the difference in target height.

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