Research and application of improved thin-layer element method of aero-engine bolted joints

2016 ◽  
Vol 231 (5) ◽  
pp. 823-839 ◽  
Author(s):  
Xingyu Yao ◽  
Jianjun Wang ◽  
Xue Zhai
Keyword(s):  
Stress Distribution ◽  
Thin Layer ◽  
Contact Stress ◽  
Experimental Results ◽  
Bolted Joints ◽  
Material Parameters ◽  
Aero Engine ◽  
Interface Contact ◽  
Contact Stress Distribution ◽  
Element Method

A new dynamic modeling method called the improved thin-layer element method is proposed to apply to the aero-engine bolted joints. The thin-layer elements are partitioned based on the interface contact stress distribution. In addition, the material parameters of the partitioned thin-layer elements are determined by the bolted joints stiffness technique and the fractal contact theory without the experimental results, which allows the engineer to estimate the dynamic characteristics of whole structure before the physical prototype is available. First, the modeling principles of the improved thin-layer element method are studied and the bolted joints stiffness is analyzed. Next, the material parameters of the partitioned thin-layer elements are determined on the basis of the interface contact stress distribution characteristics of the bolted joints. Finally, this method is applied to the simulative casing bolted joints structure and the results are compared with the experimental results in order to verify the proposed method. The results indicate that the improved thin-layer element method is more accurate than the thin-layer elements method, and the material parameters of the partitioned thin-layer elements can be expressed by the structural parameters of the aero-engine bolted joints without updating based on the experiment.

FEM Stress Analyses of the Contact Stress Distributions at the Bearing Surfaces in Bolted Joints Using Hexagon Bolts With Flanges

2010 ◽  
Author(s):  
Yukio Morozumi ◽  
Masahiko Okumura ◽  
Toshiyuki Sawa ◽  
Kengo Kuwaki
Keyword(s):  
Stress Distribution ◽  
Contact Stress ◽  
Slope Angle ◽  
Bolted Joints ◽  
Stress Distributions ◽  
Bearing Surface ◽  
Permanent Set ◽  
Flange Thickness ◽  
The Difference ◽  
Contact Stress Distribution

In designing bolted joints, it is important to understand the contact stress distribution and permanent set at the bearing surface in the case of high initial axial tension. They are investigated using elasto-plastic FEM for hexagon bolts with flange. It is found that the difference in the contact stress distribution is large between elastic FEM and elasto-plastic FEM. Effects of the flange thickness and the flange slope angle on the contact stress distribution and permanent set are examined, and it is shown that they are substantially influential. In the experiments, hollow cylindrical specimens are compressed by the bolts with flange and permanent sets are measured at the bearing surface. The permanent sets are compared with permanent sets obtained from the elasto-plastic FEM and they are in a fairly good agreement. In addition, the equivalent length for the hexagon bolt with flange is proposed.

Elastoplastic Frictional Contact Study on Interference Fits of Compressor

2011 ◽  
Vol 211-212 ◽  
pp. 535-539
Author(s):  
Ai Hua Liao
Keyword(s):  
Stress Distribution ◽  
Contact Stress ◽  
Frictional Contact ◽  
Contact Problems ◽  
Boundary Problems ◽  
Interference Fit ◽  
Parametric Variational Principle ◽  
Design And Manufacturing ◽  
Contact Stress Distribution ◽  
Fit Tolerance

The impeller mounted onto the compressor shaft assembly via interference fit is one of the key components of a centrifugal compressor stage. A suitable fit tolerance needs to be considered in the structural design. A locomotive-type turbocharger compressor with 24 blades under combined centrifugal and interference-fit loading was considered in the numerical analysis. The FE parametric quadratic programming (PQP) method which was developed based on the parametric variational principle (PVP) was used for the analysis of stress distribution of 3D elastoplastic frictional contact of impeller-shaft sleeve-shaft. The solution of elastoplastic frictional contact problems belongs to the unspecified boundary problems where the interaction between two kinds of nonlinearities should occur. The effect of fit tolerance, rotational speed and the contact stress distribution on the contact stress was discussed in detail in the numerical computation. The study play a referenced role in deciding the proper fit tolerance and improving design and manufacturing technology of compressor impellers.

Linear Tracking Response Measurements: Determining Effects of Wheel-Load Configurations

1997 ◽  
Vol 1570 (1) ◽  
pp. 1-9
Author(s):  
J. Groenendijk ◽  
C. H. Vogelzang ◽  
A. A. A. Molenaar ◽  
B. R. Mante ◽  
L. J. M. Dohmen
Keyword(s):  
Stress Distribution ◽  
Contact Stress ◽  
Wheel Load ◽  
Strain Effects ◽  
Relative Strain ◽  
Extreme Load ◽  
Tracking Device ◽  
Tracking Response ◽  
Contact Stress Distribution ◽  
Load Conditions

The relative strain effects of 15 different load configurations were studied. Using the linear tracking device (LINTRACK) accelerated loading facility, two 5-year-old pavements of 0.15-m asphalt on sand (one virgin and one loaded with 4 million 75-kN wheel loads) were tested. All measured strains were converted to strain factors relative to a standard load (super-single tire, 50 kN, 0.70 MPa). The results were compared with earlier measurements and BISAR-calculated factors. The results on the loaded pavement showed markedly more variation than those on the unloaded pavement. Generally, the BISAR-calculated relative strain factors matched the measured values well for the super-single tire. Considerable difference occurred only in the most extreme load conditions. Nonuniform contact stress distribution can be the cause for this. The calculated relative strain factors for the dual tire configurations underestimated the measured values.

scholarly journals Research on the Shock Response Characteristics of a Threaded Connection Using the Thin-Layer Element Method

2021 ◽  
Vol 11 (12) ◽  
pp. 5611
Author(s):  
A’min Yan ◽  
Xiaofeng Wang ◽  
He Yang ◽  
Fenglei Huang ◽  
Aiguo Pi
Keyword(s):  
Dynamic Response ◽  
Thin Layer ◽  
Contact Stiffness ◽  
Maximum Error ◽  
Elastic Model ◽  
Material Parameters ◽  
Response Characteristics ◽  
Threaded Connection ◽  
Constraint Method ◽  
Element Method

Nonlinear factors such as the contact stiffness and friction damping at the threaded interface of a projectile–fuse system significantly affect the dynamic response characteristics. To obtain the dynamic response of the fuse body accurately during penetration, it is necessary to characterize these nonlinear factors reasonably. Because the existing structural dynamics software cannot effectively deal with nonlinear factors, the thin-layer element method was used to represent the nonlinear factors in this study. By combining the thread elastic model with thin-layer element principles, an effective method for determining the material parameters of the thin-layer element was established theoretically, which provided a different method of determining material parameters, not just relying on experiments. The accuracy of the material parameters was verified based on modal experiments with threaded tubes having different specifications. The errors were within 5%, indicating the reliability of the theoretical determination method for the material parameters. In addition, projectile penetration into a semi-infinite concrete target was tested to verify the accuracy of the thin-layer element modeling. Compared with the ‘TIED’ constraint method, the resonant frequency obtained with the thin-layer element method was in better agreement with that of the experimental data. The maximum error decreased from 15.7 to 7.8%, indicating that the thin-layer element method could accurately represent the nonlinear factors. Thus, this study serves as a reference for accurately evaluating the dynamic response of the fuse body of a penetrator.

Simple Model for Contact Stress of Strands Bent over Circular Saddles

2016 ◽  
Author(s):  
Sherif Mohareb ◽  
Arndt Goldack ◽  
Mike Schlaich
Keyword(s):  
Simple Model ◽  
Stress Distribution ◽  
Contact Force ◽  
Contact Stress ◽  
Flexural Rigidity ◽  
Strong Nonlinearity ◽  
Stress Distributions ◽  
Maximum Contact ◽  
Contact Stress Distribution ◽  
Peak Value

Cable-stayed and extra-dosed bridges are today widely used bridge types. Recently, saddles have been used to deviate strands of cables in the pylons. Up to now the mechanics of strands on saddles are not well understood. It was found, that typical longitudinal contact stress distributions between strand and saddle show a strong nonlinearity and a high peak value around the detachment point, where the strand meets the saddle. This paper presents a procedure to analyse the longitudinal contact stress distribution obtained by FEM calculations: This contact stress can be idealised as a constant contact stress according to the Barlow's formula and a contact force at the detachment point due to the flexural rigidity of the bent tension elements. An analytical model is provided to verify this contact force. Finally, a formula is presented to calculate the maximum contact stress. This study provides the basis for further research on saddle design and fatigue of strands.

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