A Tetraparametric Metamodel for the Simulation and Optimization of Bolting Sequences for Wind Generator Flanges

2010 ◽  
Author(s):  
Mikel Abasolo ◽  
Josu Aguirrebeitia ◽  
Rafael Avile´s ◽  
Igor Fernandez de Bustos
Keyword(s):  
Computational Cost ◽  
Nonlinear Behavior ◽  
Elastic Interaction ◽  
Bolted Joints ◽  
Experimental Measurements ◽  
Assembly Process ◽  
Simulation And Optimization ◽  
Wind Generator ◽  
Bolt Preload ◽  
Contact Surfaces

In the bolted joints of wind generator flanges there is a gap between the contact surfaces of the flanges. This involves a nonlinear behavior of the system during the tightening sequence of the joint. This phenomenom, in addition with the elastic interaction, makes it difficult to achieve a uniform bolt preload at the end of the assembly process. This work presents a methodology which, based on a metamodel created for such purpose, enables the optimization of the tightening sequence; i.e. it calculates the load to be applied to each bolt in order to achieve a desired uniform preload at the end of the tightening sequence. This optimization is done with a minimum computational cost, avoiding costly experimental measurements or nonlinear FE simulations. Besides, the methodology also takes into account that the load for any bolt must be below its yield point, and therefore calculates a two-pass sequence if necessary.

A Tetraparametric Metamodel for the Analysis and Design of Bolting Sequences for Wind Generator Flanges

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Mikel Abasolo ◽  
Josu Aguirrebeitia ◽  
Rafael Avilés ◽  
Igor Fernández de Bustos
Keyword(s):  
Finite Element ◽  
Computational Cost ◽  
Elastic Interaction ◽  
Bolted Joints ◽  
Experimental Measurements ◽  
Fe Model ◽  
Analysis And Design ◽  
Linear Elastic ◽  
Wind Generator ◽  
Contact Surfaces

This paper presents a metamodel that enables estimation of the elastic interaction that occurs in the bolted joints of a wind generator tower during the tightening sequence. In this kind of joint, there is a gap between the contact surfaces of the flanges. The metamodel is composed of four parameters, which are enough to simulate the response of the flange under the tightening loads of the bolts. Even though the behavior of the joint is nonlinear because of the gap, the parameters are obtained from two simple linear elastic analyses of a finite element (FE) model of the flange. The corresponding loss of load in the bolts has been estimated for various sequences with minimum computational cost. Thus, there is no need for costly experimental measurements or nonlinear FE simulations.

Methodology for the Optimization of Bolting Sequences for Wind Generator Flanges

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Mikel Abasolo ◽  
Josu Aguirrebeitia ◽  
Rafael Avilés ◽  
Igor Fernández de Bustos
Keyword(s):  
Pressure Vessel ◽  
Computational Cost ◽  
Elastic Interaction ◽  
Optimization Methods ◽  
Bolted Joints ◽  
Wind Generator ◽  
Contact Surfaces ◽  
Number Of Passes ◽  
Low Computational Cost

In bolted joints, bolts are tightened to a uniform preload in order to improve their operational behavior. This preload is not easy to achieve due to several phenomena that occur during the tightening sequence; in the case of wind generator bolted joints, which present a gap between the contact surfaces of the flanges, the elastic interaction is by far the most prejudicial of them. As a consequence, the tightening sequence is very costly, typically consisting on a large number of passes. Based on a metamodel created in previous work, this work presents methodology for the optimization of the tightening sequence, which consists on calculating the load to be applied to each bolt so as to achieve the target uniform preload at the end of the sequence in only one pass or two at the most. This methodology is based on optimization methods used for pressure vessel bolted joints has provided satisfactory results (validated via FE analyses) with a very low computational cost.

Optimized Bolt Tightening Sequences in Bolted Joints Using Superelement FE Modeling Technique

2018 ◽  
Author(s):  
Ibai Coria ◽  
Iñigo Martín ◽  
Hakim Bouzid ◽  
Iker Heras ◽  
Josu Aguirrebeitia
Keyword(s):  
Elastic Interaction ◽  
Bolted Joints ◽  
Fe Modeling ◽  
Bolted Joint ◽  
Assembly Time ◽  
Load Variations ◽  
Computational Costs ◽  
Bolt Preload ◽  
Optimization Methodology ◽  
Number Of Passes

A lot of effort is put to achieve bolt preload uniformity during the assembly process of offshore bolted joint connections resulting in potentially high economic costs and project delays. The complexity of this operation is due to the effect of the elastic interaction between the different joint elements which causes load variations of adjacent bolts whenever a bolt is tightened. As a consequence, it is difficult to achieve a uniform target load in the bolts. In order to avoid this phenomenon, tightening sequences of a large number of passes are usually carried out until a uniform target load is achieved. This solution is neither practical nor efficient when treating hundreds or even thousands of bolted joints due to the large assembly time needed. Several methods were developed to study the effect of the elastic interaction and minimize the assembly time. These methods usually predict the loss of load of every bolt during the tightening sequence, and thus calculate the tightening loads that will provide a uniform final load at the end of the sequence. As a result, an optimized tightening sequence is achieved, which provides a uniform final load distribution in only one or two tightening passes. However, several complex and costly analyses are previously necessary for such purpose. Based on these traditional methods, this paper presents a new and more efficient optimization methodology to achieve assembly bolt load uniformity. The method is based on the use of superelement technique and is capable of producing similar results with computational costs reduced by 30 times as compared to the more conventional Finite Element (FE) modeling. The results were satisfactorily validated with the latter as well as with tests conducted on a NPS 4 class 900 bolted joint.

Numerical Simulation of the Assembly Process of Bolted Flange Joints Used in Rotating Machinery

2020 ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong ◽  
Zhenming Shi
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Elastic Interaction ◽  
Rotating Machinery ◽  
Least Square ◽  
Bolted Joints ◽  
Fe Method ◽  
Element Analysis ◽  
Bolt Preload ◽  
Bolted Flange

Abstract Bolted joints are widely used to connect structural components in rotating machinery. However, the initial tightening of the bolts is a delicate operation because it is extremely difficult to achieve the target load and uniformity due to elastic interaction. The scatter in the bolt preload has a major impact on the concentricity and consequently the dynamic behavior of rotating machinery. The risk of failure due to vibration and fatigue under service loading becomes an issue. This paper treats the effect of elastic interaction on the eccentricity during the tightening of bolted joints of rotating machinery using finite element (FE) method. In this regard, a two-component bolted flange joint of a high pressure compressor (HPC) of an aero-engine is investigated. The component surface tolerances measured by Rotary Precision Instruments (RPI) are taken into account in the numerical simulation. A method is proposed to calculate the concentricity of components obtained from the radial runout data based on the Least Square method (LSM). The scatter in bolt preload under different interference fit, surfaces tolerance, initial preload, and tightening sequence are evaluated. Furthermore, the influence of these structures and tightening sequence parameters on the concentricity are investigated. The validity of the finite element analysis is supported by experimental tests conducted on scaled specimens of HPC. This study can provide guidance and enhance the dynamic performance of bolted joints for rotating machinery.

scholarly journals Modeling and Simulating the Static Structural Response and Lift Off of a Preloaded Bolted Joint on a Flange

Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 10
Author(s):  
Rami Alfattani
Keyword(s):  
Structural Response ◽  
Segment Length ◽  
Bolted Joint ◽  
Element Analysis ◽  
Linear Finite Element ◽  
Bolt Preload ◽  
Gap Opening ◽  
Parametric Studies ◽  
Contact Surfaces ◽  
Lift Off

The present paper describes the structural analysis performed on a preloaded bolted joint. The first joint modeled was comprised of a conventional cylindrical flange that was sliced to simplify the analysis for two bolts in lieu of four. This involved an L-shaped flat segment flange. Parametric studies were performed using elastic, large-deformation, non-linear finite element analysis to determine the influence of several factors on the bolted-joint response. The factors considered included bolt preload, contact surfaces, edge boundary conditions, and joint segment length in this first approach. The second model applied the previous preloaded torque on a complex flange to study the flange lift off. Joint response is reported in terms of displacements, gap opening, and surface strains. Most of the factors studied were determined to have minimal effect on the bolted joint response.

A Novel Methodology to Optimize the Tightening Sequence in Bolted Flange Joints

2019 ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong
Keyword(s):  
Experimental Tests ◽  
Elastic Interaction ◽  
Pressure Vessels ◽  
Successful Operation ◽  
Element Analysis ◽  
Bolt Preload ◽  
Safety And Reliability ◽  
Complex Structural ◽  
Leakage Failure ◽  
Bolted Flange

Abstract Bolted flange joints are the most complex structural components of pressure vessels and piping equipment. Their assembly is a delicate task that determines their successful operation during the service life. During bolt tightening, it is very difficult to achieve uniformity of the target bolt preload due to elastic interaction and criss-cross talk. The risk of leakage failure under service loading is consequently increased because of the scatter of the bolt preload. In previous work, an analytical model based on the theory of circular beams on linear elastic foundation was proposed to predict the bolt tension change due to elastic interaction. Based on this model, this paper presents a novel methodology for the optimization of the tightening sequence. The target preload and the load to be applied to each bolt in each pass can be calculated to achieve uniform final preload and avoid bolt tension reaching yield under a number of specified tightening passes. The validity of the approach is supported by experimental tests conducted on a NPS 4 class 900 welding neck flange joint and by finite element analysis on this bolted joint using the criss-cross tightening and sequential patterns. This study provides guidelines for bolted flange joints assembly and enhances its safety and reliability by minimizing bolt tension scatter due to elastic interaction.

Simulation and Optimization of Airframe Assembly Process

2018 ◽  
Author(s):  
Sergey Lupuleac ◽  
Nadezhda Zaitseva ◽  
Maria Stefanova ◽  
Sergey Berezin ◽  
Julia Shinder ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Statistical Analysis ◽  
Problem Solving ◽  
Contact Problem ◽  
Quality Measures ◽  
Assembly Process ◽  
Variation Analysis ◽  
Simulation And Optimization ◽  
The Mathematical Model ◽  
Variation Simulation

An approach for simulating the assembly process where compliant airframe parts are being joined by riveting is presented. The foundation of this approach is the mathematical model based on the reduction of the corresponding contact problem to a Quadratic Programming (QP) problem. The use of efficient QP algorithms enables mass contact problem solving on refined grids, which is needed for variation analysis and simulation as well as for the consequent assembly process optimization. To perform variation simulation, the initial gap between the parts is assumed to be stochastic and a cloud of such gaps is generated based on statistical analysis of the available measurements. The developed approach is illustrated with two examples, simulation of A350-900 wing-to-fuselage joining and optimization of A320 wing box assembly. New contact quality measures are discussed.

Research on preload of bolted joints tightening sequence-related relaxation considering elastic interaction between bolts

2019 ◽  
Vol 160 ◽  
pp. 45-53 ◽  
Author(s):  
Ying Li ◽  
Zhifeng Liu ◽  
Yuezhen Wang ◽  
Ligang Cai ◽  
Wenxiang Xu
Keyword(s):  
Elastic Interaction ◽  
Bolted Joints

FLANGED JOINT ANALYSIS: A SIMPLIFIED METHOD BASED ON ELASTIC INTERACTION

1993 ◽  
Vol 17 (2) ◽  
pp. 181-196 ◽  
Author(s):  
A. Bouzid ◽  
A. Chaaban
Keyword(s):  
Fluid Pressure ◽  
Elastic Interaction ◽  
Bolted Joints ◽  
Joint Analysis ◽  
Simple Analytical Model ◽  
Good Design ◽  
Sealing Performance ◽  
Internal Fluid ◽  
Simplified Method ◽  
Joint Behaviour

Structurally sound bolted joints often fail due to loss of tightness. This is because the clamping load is affected by the application of the internal fluid pressure. A good design technique should therefore encompass most aspects of joint behaviour and produce efficient sealing performance within the clearly defined limits of the method used. This paper presents a simple analytical model based on an extension of the Taylor Forge approach taking into account flange rotation, flexibility of both the gasket and the bolts and, when applicable, the stiffness of the end closure. Examples will be discussed based on experimentally determined gasket properties.

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