Variation simulation model for pre-stress effect on welding distortion in multi-stage assemblies

2018 ◽  
Vol 127 ◽  
pp. 832-843 ◽  
Author(s):  
Wooyoung Choi ◽  
Hyun Chung
Keyword(s):  
Simulation Model ◽  
Welding Distortion ◽  
Stress Effect ◽  
Multi Stage ◽  
Variation Simulation

Tolerance Analysis and Diagnosis Model of Compliant Block Assembly Considering Welding Deformation

2015 ◽  
Author(s):  
Junghyun Lee ◽  
Wooyoung Choi ◽  
Minseok Kang ◽  
Hyun Chung
Keyword(s):  
Tolerance Analysis ◽  
Normal Equation ◽  
Welding Distortion ◽  
Assembly Process ◽  
Accuracy Control ◽  
Mechanical Assembly ◽  
Multi Stage ◽  
Proposed Model ◽  
Diagnosis Model ◽  
Welding Processes

This paper proposes a simplified tolerance analysis and diagnosis model including the effects of welding distortion, for accuracy control in ship block assembly processes. The variation simulation model for tolerance analysis utilizes the concepts of the sources of variation and the compliant mechanical assembly model to include the welding distortions. The proposed model utilizes welding distortion patterns and a transformation matrix to efficiently model the deformation during the joining process. The diagnosis model assumes the multi-stage assemblies and that the variations of previous stages are propagated to the current stage. It calculates the sensitivity; a linear mapping from input parts to output assembly variations, and includes the effects of welding distortion as an additional vector that deviates the assembly variation further. The diagnosis model predicts the quantitative effect of each source of variations to the final assembly’s geometrical variation, based on normal equation and assembly stage’s state space equation model. The proposed model is applied to a realistic block assembly process for validation purpose. The model can effectively simulate the propagation of welding distortion as well as quantitatively identify variation patterns and welding processes throughout the multi-stage assembly process.

Vibration Control of Erecting System Based on Fuzzy Adaptive PID Controller

2014 ◽  
Vol 945-949 ◽  
pp. 785-789
Author(s):  
Zheng Xie ◽  
Jian Xie ◽  
Wen Zheng Du ◽  
Ding Jun Huang
Keyword(s):  
Simulation Model ◽  
Vibration Control ◽  
Pid Controller ◽  
The Other ◽  
Control Performance ◽  
Multi Stage ◽  
Fuzzy Adaptive

To reduce the influences of vibration of large erecting system in the process of erecting, this paper firstly built a simulation model, then an erect angle velocity was planned so that it can minimize the velocity at the stage of beginning, multi-stage cylinder stage changing and arriving, thus the velocity at the other stages can be increased . Meanwhile the fuzzy adaptive PID controller was applied to track the erect angle curve. Finally, the simulation validates that the vibration and shock are effectively reduced by this method. Fast and stable erection of the load is realized. Compared with the original PID controller, the fuzzy adaptive PID controller can be proved to have a better control performance.

On the Robustness of the Volumetric Shrinkage Method in the Context of Variation Simulation

2014 ◽  
Author(s):  
Samuel Lorin ◽  
Christoffer Cromvik ◽  
Fredrik Edelvik ◽  
Lars Lindkvist ◽  
Rikard Söderberg
Keyword(s):  
Mechanical Analysis ◽  
Volumetric Shrinkage ◽  
Welding Distortion ◽  
Uniform Temperature ◽  
Approximate Methods ◽  
Melted Region ◽  
Welded Structure ◽  
Shrinkage Method ◽  
Static Mechanical ◽  
Variation Simulation

Welding induces high temperatures that cause residual stresses and strains in the welded structure. With a welding simulation, these stresses and strains may be predicted. A full simulation implies performing a transient thermal and a quasi-static mechanical analysis. These analyses usually involve a large number of time steps that leads to long simulation times. For welding distortions, there are approximate methods that require considerably less time. This is useful when simulating large structures or for analyses that use an iterative approach common in optimization or variation simulation. One of these methods is volumetric shrinkage, which has been shown to give reasonable results. Here it is assumed that the driving force in welding distortion is the contraction of the region that has been melted by the weld. In volumetric shrinkage, the nodes that are inside the melted region are assigned a uniform temperature and the distortion is calculated using elastic volumetric shrinkage. Although this method has been shown to give reasonable predictions, we will show that it is sensitive to small perturbations, which is an essential part in variation simulation. We also propose a modification of the volumetric shrinkage method that addresses this lack of robustness; instead of defining the melted region by applying a uniform temperature to the nodes inside the zone, we formulate an optimization problem that finds a temperature distribution such that the local melted volume is preserved. A case study with application to variation simulation has been used to elicit the proposed method.

Variation Simulation of Welded Assemblies Using a Thermo-Elastic Finite Element Model

2014 ◽  
Vol 14 (3) ◽  
Author(s):  
Samuel Lorin ◽  
Christoffer Cromvik ◽  
Fredrik Edelvik ◽  
Lars Lindkvist ◽  
Rikard Söderberg
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Welding Distortion ◽  
Elastic Model ◽  
Reasonable Accuracy ◽  
Statistical Accuracy ◽  
Manufactured Products ◽  
Geometric Variation ◽  
Variation Simulation

Every series of manufactured products has geometric variation. Variation can lead to products that are difficult to assemble or products not fulfilling functional or aesthetic requirements. In this paper, we will consider the effects of welding in variation simulation. Earlier work that has been combining variation simulation with welding simulation has either applied distortion based on nominal welding conditions onto the variation simulation result, hence loosing combination effects, or has used transient thermo-elasto-plastic simulation, which can be very time consuming since the number of runs required for statistical accuracy can be high. Here, we will present a new method to include the effects of welding in variation simulation. It is based on a technique that uses a thermo-elastic model, which previously has been shown to give distortion prediction within reasonable accuracy. This technique is suited for variation simulations due to the relative short computation times compared to conventional transient thermo-elasto-plastic simulations of welding phenomena. In a case study, it is shown that the presented method is able to give good predictions of both welding distortion and variation of welding distortions compared to transient thermo-elasto-plastic simulations.

Modeling and Simulation of a Surface Micromachined Knudsen Pump

2006 ◽  
Author(s):  
Naveen K. Gupta ◽  
Yogesh B. Gianchandani
Keyword(s):  
Simulation Model ◽  
Thermal Response ◽  
Gas Diffusion ◽  
Input Power ◽  
Single Stage ◽  
Analytical Estimate ◽  
Narrow Channels ◽  
Wide Channel ◽  
Multi Stage ◽  
Knudsen Pump

This paper presents a simulation model for a silicon micromachined Knudsen pump that combines analytical and numerical methods. It involves numerical modeling of the thermal response, followed by an analytical estimate of the pumping using Kennard's model. The loss of performance resulting from gas diffusion though walls of the pump is specifically addressed. The results are subsequently validated against the previously reported experimental measurements of a single-stage Knudsen pump. This device, which has a total footprint of less than 1500 × 2000 μm2, has multiple narrow channels connecting two cavities, one of which is heated. This cavity is further connected through a wide channel to a third cavity, which remains at ambient. The simulation model for this device predicts a vacuum pressure of 0.47 atm. at an input power of 97.6 mW, which deviates less than 20% from the experimentally observed data. Finally, the paper extends the concept of single stage pumping to a multi-stage pump. While Kennard's model is used for modeling the first stage, the simulation for subsequent stages, which are characterized by a relatively high Knudsen number, uses an empirically corrected

Variation Simulation Considering Welding Distortion Applied in High-Speed Trains

2017 ◽  
Author(s):  
Zhimin Li ◽  
Limin Yao ◽  
Baowang Li
Keyword(s):  
High Speed ◽  
Side Wall ◽  
Tolerance Analysis ◽  
Angular Distortion ◽  
Welding Distortion ◽  
High Speed Train ◽  
High Speed Trains ◽  
Dimensional Variation ◽  
Variation Simulation

The high-speed trains are currently considered one of the most significant technological breakthroughs in passenger transportation for providing lower time-consuming and higher quality improvement services. Nevertheless, the manufacturing quality of high speed train is related to driving safety and riding comfort. It needs to be emphasized that the control of dimensional variation plays a crucial and irreplaceable role in today’s manufacturing processing which affect the quality of manufacturing. In this study, a variation simulation method considering both tolerance analysis with rigid assumption and welding distortion is developed to predict dimensional variation of the side wall of high-speed train during the assembly process. Firstly, the tolerance analysis with rigid assumption method is employed to simulate the dimensional variation when the parts of side wall are assembled together. Then, the finite element method (FEM) based on inherent strain is used to predict welding distortion including longitudinal shrinkage, transverse shrinkage and angular distortion. Finally, the results combining both tolerance analysis with rigid assumption and welding distortion are compared with actually measured results to identify the effectiveness of this method.

Variation Simulation of Welded Assemblies Using a Thermo-Elastic Finite Element Model

2013 ◽  
Author(s):  
Samuel Lorin ◽  
Christoffer Cromvik ◽  
Fredrik Edelvik ◽  
Lars Lindkvist ◽  
Rikard Söderberg
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Welding Distortion ◽  
Elastic Model ◽  
Reasonable Accuracy ◽  
Statistical Accuracy ◽  
Manufactured Products ◽  
Geometric Variation ◽  
Variation Simulation

Every series of manufactured products has geometric variation. Variation can lead to products that are difficult to assemble or products not fulfilling functional or aesthetical requirements. In this paper, we will consider the effects of welding in variation simulation. Earlier work that have been combining variation simulation with welding simulation have either applied distortion based on nominal welding conditions onto the variation simulation result, hence loosing combination effects, or have used transient thermo-elasto-plastic simulation, which can be very time consuming since the number of runs required for statistical accuracy can be high. Here, we will present a new method to include the effects of welding in variation simulation. It is based on a technique that uses a thermo-elastic model, which previously has been shown to give distortion prediction within reasonable accuracy. This technique is suited for variation simulations due to the relative short computation times compared to conventional transient thermo-elasto-plastic simulations of welding phenomena. In a case study, it is shown that the presented method is able to give good predictions of both welding distortion and variation of welding distortions compared to transient thermo-elasto-plastic simulations.

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