Parametric sensitivity research of interference-fit bolted single-lap laminates joint based on an improved analytical stiffness model

2021 ◽  
pp. 002199832110417
Author(s):  
Yuan Yang ◽  
Peng Zou ◽  
Xilin Dai ◽  
Bo Yang ◽  
Feng Gao
Keyword(s):  
Laminated Composite ◽  
Bending Moment ◽  
Shear Stiffness ◽  
Analytical Prediction ◽  
Structural Stiffness ◽  
Key Factors ◽  
Interference Fit ◽  
Moment Coefficient ◽  
Bolt Preload ◽  
Stiffness Model

Because of the excellent static and fatigue performance, the interference-fit bolted structure has a wide application prospect in the joint field. In this paper, an improved spring-mass stiffness analytical prediction model is established for the interference-fit bolted single-lap laminated composite structure. The influences of interference-fit percentage, bolt preload, secondary bending and interface frictions are considered in the model. Combined with experimental research, the value of secondary bending moment coefficient ε is studied, and the correctness of the analytical model is verified. Based on the improved stiffness model, parametric research and regression analysis on the interference-fit percentage, preload, friction, laminate width and material properties are carried out and show that the overall structure stiffness is obviously affected by ε value, laminate width and laminates properties. The stiffness decreases with the increase of ε and increases with the increase of laminate width. And as the key factors, the interference-fit percentage mainly affects the joint local friction and bolt shear stiffness, the preload and friction coefficient mainly affect the local friction, and the laminates sizes and properties directly affect the overall structural stiffness.

A realistic model for transverse shear stiffness prediction of composite corrugated-core sandwich structure with bonding effect

2021 ◽  
pp. 109963622199386
Author(s):  
Tianshu Wang ◽  
Licheng Guo
Keyword(s):  
Present Model ◽  
Shear Stiffness ◽  
Realistic Model ◽  
Torsional Stiffness ◽  
Fem Model ◽  
The Core ◽  
Bonding Effect ◽  
Stiffness Model ◽  
Bonding Area ◽  
The Relationship

In this paper, a shear stiffness model for corrugated-core sandwich structures is proposed. The bonding area is discussed independently. The core is thought to be hinged on the skins with torsional stiffness. The analytical model was verified by FEM solution. Compared with the previous studies, the new model can predict the valley point of the shear stiffness at which the relationship between the shear stiffness and the angle of the core changes from negative correlation to positive correlation. The valley point increases when the core becomes stronger. For the structure with a angle of the core smaller than counterpart for the valley point, the existing analytical formulations may significantly underestimate the shear stiffness of the structure with strong skins. The results obtained by some previous models may be only 10 persent of that of the present model, which is supported by the FEM model.

Design guidelines for bump-type compliant conical foil bearing

2021 ◽  
pp. 095440622110127
Author(s):  
Hongyang Hu ◽  
Ming Feng
Keyword(s):  
Load Capacity ◽  
Design Guidelines ◽  
Foil Thickness ◽  
Axial Stiffness ◽  
Structural Stiffness ◽  
Foil Bearing ◽  
Stiffness Model ◽  
Opposite Position ◽  
Stiffness Distribution ◽  
Half Length

The integral bump foil strip cannot optimize the performance for the compliant conical foil bearing (CFB) as the uneven distribution of structural stiffness. To maximize the bearing characteristics, this paper proposed different bump foil schemes. Firstly, the anisotropy of CFB was studied based on the nonlinear bump stiffness model, and the circumferentially separated foil structure was proposed. Moreover, an axially separated bump foil structure with the variable bump length was introduced to make the axial stiffness distribution more compliant with the gas pressure. In addition, the effect of foil thickness was also discussed. The results show that CFB with integral bump foil exhibits obvious anisotropy, and the suggested installation angle for largest load capacity and best dynamic stability are in the opposite position. Fortunately, a circumferential separated bump foil can improve this defect. The characteristics of CFB with axial separated foil structure can be improved significantly, especially for that with more strips and the variable bump half-length design. The suitable bump and top foil thickness should be set considering the improved supporting performance and proper flexibility. The results can give some guidelines for the design of CFB.

Analytical and numerical investigation of bending moment coefficient in balanced single lap joints

2015 ◽  
Vol 44 (5) ◽  
pp. 173-181 ◽  
Author(s):  
G. C. Papanicolaou ◽  
P. J. Charitidis ◽  
D. E. Mouzakis ◽  
G. Jiga
Keyword(s):  
Numerical Investigation ◽  
Bending Moment ◽  
Lap Joints ◽  
Single Lap Joints ◽  
Moment Coefficient

Evaluation of Sealing Performance of Pipe Flange Connection Subjected to External Bending Moments

2009 ◽  
Author(s):  
Yoshio Takagi ◽  
Hiroyasu Torii ◽  
Toshiyuki Sawa ◽  
Kensuke Funada
Keyword(s):  
Bending Moment ◽  
Bending Moments ◽  
Stress Strain ◽  
Flange Connection ◽  
Strain Behavior ◽  
Leakage Test ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Non Linear

The sealing performance of pipe flange connection subjected to an external bending moment was evaluated with the FEM and the experiments. The experimental leakage test using water revealed that the bending moment had an important effect on the sealing performance. The FE analyses suggested that the contact gasket stress, which was a function of the bolt preload, determines the leakage. The changes in contact gasket stress at tension side and compression side when the external bending moment applied were not symmetrical. The reduction in the contact gasket stress of tension side was larger than that of compression side due to the non-linear stress-strain behavior of the gasket. In addition, the hub stress of the flange when external bending moment applied, was evaluated from FE result and the discussion for optimizing the flange design subjected to external bending moment was done in this paper.

Stress Analysis and the Sealing Performance Evaluation of Pipe Flange Connections With Gaskets Subjected to Internal Pressure and External Bending Moment: Effects of Scatter in Bolt Preload

2004 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Wataru Maezaki ◽  
Satoshi Nagata
Keyword(s):  
Finite Element Method ◽  
Internal Pressure ◽  
Control Method ◽  
Bending Moment ◽  
Torque Control ◽  
Stress Distributions ◽  
Gas Leakage ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Spiral Wound

It has been well known that a scatter in axial bolt forces of pipe flange connections tightened by the torque control method is substantial. It is necessary for evaluating the sealing performance of the pipe flange connections with the gaskets subjected to internal pressure and external bending moment to know the contact gasket stress distributions due to the scatter of the axial bolt forces in the connections tightened by the torque control method. This paper deals with the leakage of the pipe flange connections with a spiral wound gasket subjected to internal pressure and external bending moment tightened by the torque control method. The scattered axial bolt forces were measured in the experiments. The contact gasket stress distributions at the interfaces between pipe flanges and the gasket were calculated under the measured axial bolt force by using elasto-plastic finite element method (FEM) taking into account hysteresis and non-linearity in the stress-strain curves of spiral wound gasket. The effects of the scatter in the axial bolt forces tightened by the torque control method on the gas leakage were also examined by using the actual pipe flange connections under internal pressure and external bending moment. By using the calculated contact stress distributions and the results of the leakage tests, the sealing performance was evaluated. It is found that the sealing performance is worse in the actual pipe flange connection than that evaluated by PVRC procedure.

A New Design Conception for Large Span Deployable Flat Grid Structures

2002 ◽  
Vol 17 (4) ◽  
pp. 293-299 ◽  
Author(s):  
Chen Wujun ◽  
Fu Gongyi ◽  
Gong Jinghai ◽  
He Yanli ◽  
Dong Shilin
Keyword(s):  
Potential Application ◽  
Great Part ◽  
Bending Moment ◽  
Structural Stiffness ◽  
Grid System ◽  
Application Field ◽  
Large Span ◽  
Potential Applications ◽  
Internal Forces ◽  
Flat Grids

The deployable flat grids, consisting of only hinged pantographic units, usually have low structural stiffness, and the bending moment constitutes a great part of internal forces. This results in structural inefficiency, especially for large span grids. Diagonals (web struts) and lower chords are added herein to enhance the structural stiffness. The newly added web struts must be compatible with the deployable geometry. Cables or foldable bars can be used as lower chords. The statical determinacy characteristics are analysed for the newly proposed grid system. On the basis of this concept, several flat grids are firstly developed for potential applications. And a joint conception also developed. The structural performances are investigated for a series of deployable flat grids. Steel quantities and deflections are compared for four different grids. The results indicate that the newly proposed conception has fairly high economic scale, structural efficiency and promising potential application field.

Elasto-Plastic Stress Analysis of the Characteristics for T-Flange Bolted Joints Under External Loading

2013 ◽  
Author(s):  
Yuya Omiya ◽  
Toshiyuki Sawa
Keyword(s):  
Stress Analysis ◽  
Tensile Load ◽  
Bending Moment ◽  
Bolted Joints ◽  
External Loading ◽  
Load Factor ◽  
Bolted Joint ◽  
Bearing Surface ◽  
Permanent Set ◽  
Bolt Preload

In designing bolted joints, it is necessary to know the contact stress distributions in bolted joints. Recently, high strength bolts have been used with a higher bolt preload. As the results, the permanent set occurs sometimes at the bearing surfaces of clamped parts in the bolted joint. In addition, when external loads such as tensile loads, transverse loads and bending moments are applied to the bolted joint, the permanent set can be extended at the bearing surfaces. As the permanent set increases, the reduction in the bolt preload increases. Thus, it is important to estimate the reduction in the bolt preload from the reliability stand point. However, no study on the permanent set at the bearing surface under the external loading taking into account the bending moment has been carried out. In this study, the stress distribution and the extension of the permanent set at the bearing surface of the T-flange bolted joint under the external tensile loading are examined using Finite Element Method (FEM), where two T-flanges are clamped with a hexagon bolt and a nut. Using the obtained results, an increment in the axial bolt force and the reduction in the bolt preload are estimated. For verification of the FEM stress analysis, the load factor of hexagon bolt was measured. The FEM results of the load factor (the ratio of the increment in the axial bolt force to the tensile load) and the axial bolt force are in a fairly good agreement with the experimental results.

scholarly journals Nonlinear Connection Stiffness Identification of Heritage Timber Buildings Using a Temperature-Driven Multi-Model Approach

2020 ◽  
Vol 20 (10) ◽  
pp. 2042001
Author(s):  
Qingshan Yang ◽  
Mengning Lyu ◽  
Xinqun Zhu
Keyword(s):  
Temperature Variation ◽  
Linear Connection ◽  
Bending Moment ◽  
Joint Rotation ◽  
Nonlinear Connection ◽  
Stiffness Identification ◽  
Stiffness Model ◽  
Temperature Ranges ◽  
Nonlinear Compression

‘Que-Ti’ is an important component in typical Tibetan heritage timber buildings and it performs similar to corbel brackets connecting beam and column in modern structures. It transfers shear, compression and bending moment by slippage and deformation of components as well as limited joint rotation. A rigorous analytical model of ‘Que-Ti’ is needed for predicting the behavior of a timber structure under extreme loadings. Few researches have been done on this topic, particularly with the parameters describing the performances of this connection subjected to external loads. In this paper, a new temperature-driven multimodel approach is proposed to identify the stiffness parameters of a ‘Que-Ti’ connection in its operating environment. Models with nonlinear compression and rotational springs have been developed to take into account the change of mechanical behavior of the ‘Que-Ti’ affected by the temperature variation in typical heritage Tibetan buildings. The column–beam connection is modeled as two nonlinear rotational springs and one nonlinear compressive spring. Ambient temperature variation is treated as a force function in the input (temperature)–output (local mechanical strains) relationship, and stiffness identification is conducted iteratively via correlating the calculated strain responses with measured data. The nonlinear model of the joint is reproduced with a number of linear local models in different deformation scenarios that are corresponding to different temperature ranges. The stiffness parameters can be identified using a multimodel approach. Numerical results show that the method is effective and reliable to identify the nonlinear connection stiffness of the ‘Que-Ti’ accurately with the temperature change even with 10% noise in measurements. The monitoring data from a long-term monitoring system installed in a typical heritage Tibetan building is used to further verify the method. The experimental results show that the identified stiffness by the proposed method with nonlinear connection stiffness model can get better results than that obtained from the linear connection stiffness model.

Laminated pipe bends of mixed wall construction subjected to an in-plane bending moment

1989 ◽  
Vol 24 (3) ◽  
pp. 127-138 ◽  
Author(s):  
R Kitching ◽  
D R Hose
Keyword(s):  
Fourier Series ◽  
Transverse Shear ◽  
Laminated Composite ◽  
Bending Moment ◽  
Numerical Results ◽  
Pipe Bend ◽  
Simple Method ◽  
Composite Pipe ◽  
Wall Construction ◽  
Plane Bending

Some of the ways in which the analysis of laminated composite pipe bends may differ from that of isotropic pipe bends are highlighted. The possible difference between effective bending and tensile moduli is recognised and its influence investigated over a range of bend geometries. A simple method for estimation of the influence of transverse shear terms on the performance of such a pipe bend under in-plane bending is presented, together with numerical results from the analysis. The range of geometries over which these terms may be important is discussed. The analysis is presented in a form which is readily implemented on a microcomputer, and suitable expressions for evaluation of appropriate Fourier series integrals are developed.

A unified small-strain shear stiffness model for saturated and unsaturated soils

2021 ◽  
Vol 136 ◽  
pp. 104241
Author(s):  
Mahnoosh Biglari ◽  
Iman Ashayeri ◽  
Domenico Gallipoli ◽  
Sara Moradpour
Keyword(s):  
Unsaturated Soils ◽  
Shear Stiffness ◽  
Small Strain ◽  
Stiffness Model ◽  
Small Strain Shear Stiffness
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