Analysis of a Bolted Joint Failure in a Hydraulic Press

2004 ◽  
Author(s):  
Jason Deadman
Keyword(s):  
Hydraulic Press ◽  
Maintenance Strategy ◽  
Bolted Joint ◽  
Element Analysis ◽  
Acceptable Solution ◽  
The Press ◽  
Dynamic Loadings ◽  
Cause Of Failure ◽  
Process Operation ◽  
Critical Process

Micrographic inspection, acceleration tests, Finite Element Analysis and detailed fatigue failure calculations for combined static and dynamic loadings, were used in determining the cause of failure, and an acceptable repair solution, for a critical bolted joint. The bolted joint holds together the piston and ram within a hydraulic press. The press had been in operation for eleven years when the failure occurred. As the press is used in a critical process operation, a repair solution and future maintenance strategy was required that would minimize the possibility of future failures and permit maintenance during planned outages. This paper discusses the method that was followed to arrive at an acceptable solution.

On the Effect of External Bending Loads in Bolted Flange Joints

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Abdel-Hakim Bouzid
Keyword(s):  
Analytical Approach ◽  
Room Temperature ◽  
Bolted Joint ◽  
Element Analysis ◽  
Acceptable Solution ◽  
Sealing Performance ◽  
Circumferential Distribution ◽  
Bending Loads ◽  
Minimum Stress ◽  
Bolted Flange

Most current flange design methods use an equivalent pressure to treat bolted flange connections subjected to external bending loads. This oversimplified approach together with the lack of a proper assessment of the actual affected tightness make these methods inadequate for modern flange design. The substitution of the external applied moment by an equivalent pressure is excessively conservative and not realistic since it assumes that the achieved tightness is that of a gasket unloaded entirely to a minimum stress whereas in reality only a small section of it is, the rest of it is actually at a much higher stress. The successfulness of a valid analytical approach in yielding to an acceptable solution resides in its ability to account for the circumferential distribution of the gasket contact stress and its effect on leakage. This paper presents an analytical model based on the flexibility of the flange to treat flanges subjected to bending loads such as those produced by external moments and misalignments and capable of integrating leakage around the gasket circumference. The bolted joint sealing performance in the presence of such loads is evaluated using the new Pressure Vessel Research Council (PVRC) gasket constants Gb, a, and Gs, obtained from room temperature tightness (ROTT) tests. The analytical results including leakage predictions are validated by comparison to those obtained numerically by finite element analysis and experimentally on different size flanges. The overconservatism of the equivalent pressure is demonstrated.

Mechanical analysis on the cylinder-crown integrated hydraulic press with a hemispherical cylinder

2014 ◽  
Vol 229 (3) ◽  
pp. 407-416
Author(s):  
WW Zhang ◽  
XS Wang ◽  
ZR Wang ◽  
SJ Yuan ◽  
ZB He ◽  
...  
Keyword(s):  
Bending Moment ◽  
Hydraulic Cylinder ◽  
Hydraulic Press ◽  
Material Strength ◽  
Element Analysis ◽  
Application Range ◽  
Section Modulus ◽  
Strength Capacity ◽  
The Press ◽  
Institute Of Technology

As a new press, cylinder-crown integrated hydraulic press (CCIHP) is analyzed firstly in this paper. The hydraulic cylinder consists of a hemispherical shell, which also functions as a main proportion of press crown. Compared with the conventional hydraulic press which has a hydraulic cylinder mounted in the press crown, the structure and force distribution of CCIHP are significantly different. First, the section modulus of the hemispherical crown is much larger than that of the conventional rectangle crown because the hydraulic cylinder and press crown are manufactured into a solid part and have a higher geometry centroid. Therefore, the hemispherical crown has lower tensile bending stress and a higher safety factor from the strength point of view when the same bending moment is applied. Second, under the conditions of same value in terms of the allowable stress, internal pressure and internal radius, the wall thickness of hemispherical hydraulic cylinder could be much thinner than that of the conventional hydraulic cylinder. Both of the reasons mentioned above can result in a weight reduction of the press. Also, the cylinder and the press crown can be reinforced by each another, as a result, the material strength capacity is better utilized. As a prototype, the 6300 kN CCIHP with hemispherical hydraulic cylinder, which is the first one of this kind press designed and manufactured by Harbin Institute of Technology (HIT) is introduced in this paper. Finite element analysis for CCIHP has shown that both the stress and displacements on the press during the loading process are allowable, even if eccentric force is loaded. Finally the priority application range of CCIHP has also been proposed.

Selection of the optimal hydraulic drive for the press

2021 ◽  
pp. 50-60
Author(s):  
A.A. Antsifirov ◽  
V.A. Krivoshein
Keyword(s):  
Technological Process ◽  
Electric Motor ◽  
Software Package ◽  
Hydraulic Drive ◽  
Hydraulic Press ◽  
Topological Model ◽  
Electric Motors ◽  
Engine Operation ◽  
The Press ◽  
Selection Of

The research presented in the article is devoted to the selection of the electric motor of the hydraulic press drive with a nominal force of 5MN. The article presents the main characteristics and the description of the press operation using the means of mechanization of the technological process of pressure treatment. Using the Deform-3D software package, the process of stamping the crosspiece of the ZIL-130 cardan shaft was simulated. Based on the presented hydraulic scheme of the press, its topological model was formed in the PA-9 software package. The deformation force obtained in the course of modeling the technological process of stamping was used in the topological model of the press. Using a tabular cyclogram, the sequence of actuation of the end switches and hydraulic distributors during the stamping process is shown. In the article, two variants of engine operation were analyzed. Based on the results of the conducted research, it is necessary to focus on the second version of the 55 kW engine, the operation of which will provide the required characteristics of the hydraulic drive of the press, which in turn will allow for technological stamping operations. The simulation tools allow providing estimated information when selecting the necessary tools to ensure the optimal characteristics of hydraulic press drives. The article considered the variation of electric motors that differ from each other in nominal characteristics, with constant characteristics of the pump. For more accurate estimates of energy savings during the operation of the hydraulic drive, it is necessary to vary the characteristics of the pump in the simulation, and the best option is to form an experiment planning matrix when combining the characteristics of the electric motor and the hydraulic pump. This approach ultimately allows forming a function for which one can select a hydraulic drive from existing brands of electric motors and hydraulic pumps for presses of the corresponding range of nominal force.

IMPROVEMENT OF THE PROCESS OF OPERATION OF THE GUIDE MOVING CROSSBARS OF HYDRAULIC PRESSES

2020 ◽  
Author(s):  
K.O. Kobzev ◽  
◽  
S.A. Vyalov ◽  
E.S. Bozhko ◽  
I.A. Zolotuhina ◽  
...  
Keyword(s):  
Service Life ◽  
Hydraulic Press ◽  
Operating Conditions ◽  
The Press ◽  
Technical Solutions

This article deals with the problem of operating conditions of guide moving crossbars of hydraulic presses. Based on the study of hydraulic press operation processes, the need to develop and implement measures to ensure reliable and trouble-free operation of the press was identified. The conclusion justifies the idea that if these technical solutions are implemented, the service life of hydraulic presses will increase

scholarly journals Column press design optimization on the basis of stress-strain state’s mathematical modeling

2018 ◽  
Vol 224 ◽  
pp. 04015 ◽  
Author(s):  
Sergey Karpushkin ◽  
Aleksey Glebov ◽  
Sergey Karpov
Keyword(s):  
Topological Optimization ◽  
Stress Strain ◽  
Element Analysis ◽  
Vertical Column ◽  
Equivalent Stresses ◽  
Study Results ◽  
The Press ◽  
The Finite Element Analysis ◽  
Rapid Changes ◽  
Expert Analysis

The problem of optimizing the design of vertical column press traverse according to the metal consumption criterion is taken into consideration. As a limitation, the maximum value of equivalent stresses in the volume of the traverse was used. It is shown that the methods of parametric and topological optimization are ineffective for solving the optimization problem. A mathematical model of the stress-strain state of the traverse is proposed, which allows carrying out simulation independently from other elements of the press. The finite element analysis of the existing structure of the traverse revealed the redundancy of the loaded elements amplification, as well as the low manufacturability of the structure. The method of expert analysis was used to find the optimal design. The effect of the thickness of the base of the traverse on the resulting equivalent stresses was studied. A new design of the traverse was proposed on the base of the study results. That design is characterized by low metal capacity and high manufacturability. It is found that the maximum stresses occur in the areas of rapid changes in shape, as well as in the areas of loads.

A Coupled Temperature-Displacement Numerical Analysis of Hydraulic Press Workspace

2016 ◽  
Author(s):  
Jakub Jirasko ◽  
Antonin Max ◽  
Radek Kottner
Keyword(s):  
Numerical Analysis ◽  
Computational Model ◽  
Automotive Industry ◽  
Elevated Temperatures ◽  
Compressive Force ◽  
Hydraulic Press ◽  
Metallic Materials ◽  
Pressing Force ◽  
Stress Criterion ◽  
The Press

The analysis is performed on a hydraulic press which is intended for use in the automotive industry and is a part of a production line. The final phase of manufacture of interior and acoustic parts takes place in this press. These interior and acoustic parts are made of sandwich fabric which is inserted into the heated mould of the press and by treatment with a defined pressure (or, more precisely, a defined compression) and temperature, it is formed into its final shape. This press has a frame with four columns and it is not preloaded. Two double acting hydraulic cylinders placed on an upper cross beam exert the compressive force. Due to continuously increasing demands on the accuracy and quality of products not only in the automotive industry, it is necessary to ensure compliance with the accuracy of certain values of machine operation. Especially in this case, the value of accuracy substantially depends on the clamping plates of the press, for which a certain value of flatness is required, both at room temperature and at elevated temperatures. To achieve this accuracy, it is necessary to guarantee sufficient stiffness of the machine to resist the pressing force with the smallest deformation possible. Another crucial factor affecting the accuracy of the machine is heating of the heated clamping plates. Unequal heating of parts of the frame causes additional deformation that has to be quantified and eliminated. The main aim was to verify the design of the press by numerical computation and gather knowledge for modifying the topological design of the press so that it fulfils the required customer parameters of flatness and parallelism for different types of loading. A computational model of the press was created for the numerical solution of a coupled temperature-displacement numerical analysis. The analysis was performed using the finite element method in Abaqus software. The press is symmetrical in two orthogonal planes and the load of the press is considered to be centric. On the basis of these two factors it was possible to carry out the analysis by considering only a quarter of the press. The analysis was used to investigate the effects of static and combined loads from the pressing force and heat on the press. The influence of a cooling circuit located in the press frame for the reduction of frame deformation (and deformation of clamping plates) was investigated. Contacts were defined among individual parts to ensure the computational model had characteristics as close as possible to the real press. The analysis was solved as stationary, on the basis that the cooling of the tool between individual pressing cycles is negligible. The insulating plates are made of a particulate composite material which was considered to have isotropic properties depending on the temperature. For strength evaluation of composite materials all individual components of the stress tensor were examined according to the maximum stress criterion. Hook’s law was considered to be valid for the metallic materials. Von Mises criterion was used to evaluate the strength of the metallic materials. The geometry of the press was discretized using 3D linear thermally coupled brick elements with 8 nodes and full integration (C3D8T). There were approximately 174,000 elements in total. Design procedures for designing a press frame with higher work accuracy (flatness) were proposed with the example of the simplified model of the press table. With these methods it is possible to achieve times higher accuracy than is achieved with conventional method.

scholarly journals Nonlinear Axial Stiffness Characteristics of Axisymmetric Bolted Joints

1990 ◽  
Vol 112 (3) ◽  
pp. 442-449 ◽  
Author(s):  
I. R. Grosse ◽  
L. D. Mitchell
Keyword(s):  
Finite Element ◽  
Linear Theory ◽  
Design Theory ◽  
Joint Stiffness ◽  
Bolted Joints ◽  
Axial Stiffness ◽  
Outer Diameter ◽  
Bolted Joint ◽  
Element Analysis ◽  
Stiffness Characteristics

A critical assessment of the current design theory for bolted joints which is based on a linear, one-dimensional stiffness analysis is presented. A detailed nonlinear finite element analysis of a bolted joint conforming to ANSI standards was performed. The finite element results revealed that the joint stiffness is highly dependent on the magnitude of the applied load. The joint stiffness changes continuously from extremely high for small applied loads to the bolt stiffness during large applied loads, contrary to the constant joint stiffness of the linear theory. The linear theory is shown to be inadequate in characterizing the joint stiffness. The significance of the results in terms of the failure of bolted joints is discussed. A number of sensitivity studies were carried out to assess the effect of various parameters on the axial joint stiffness. The results revealed that bending and rotation of the joint members, interfacial friction, and the bolt/nut threading significantly influence the axial stiffness characteristics of the bolted joint. The two-dimensional, axisymmetric finite element model includes bilinear gap elements to model the interfaces. Special orthotropic elements were used to model the bolt/nut thread interaction. A free-body-diagram approach was taken by applying loads to the outer diameter of the joint model which correspond to internal, uniformly distributed line-shear and line-moment loads in the joint. A number of convergence studies were performed to validate the solution.

Design and Manufacturing of Cylinder-Beam Integrated Hydraulic Press

2013 ◽  
Vol 397-400 ◽  
pp. 157-161
Author(s):  
Wei Wei Zhang ◽  
Xiao Song Wang ◽  
Shi Jian Yuan ◽  
Zhong Ren Wang
Keyword(s):  
Driving Force ◽  
Geometric Dimension ◽  
Hydraulic Cylinder ◽  
Hydraulic Press ◽  
Force Distribution ◽  
Section Modulus ◽  
The Press ◽  
The World ◽  
Design And Manufacturing ◽  
Institute Of Technology

For a cylinder-beam integrated hydraulic press (CBIHP), the hydraulic cylinder is also functioned as an upper beam. It is the key structural component that outputs the driving force to forge parts. Compared with the traditional three-beam and four-column hydraulic press which has a cylindrical hydraulic cylinder, the structure and force distribution are significantly different for CBIHP. It is able to have higher nominal force and larger section of plunger which the pressure is applied on when the contour geometric dimension is the same. Also, CBIHP has lighter weight and larger section modulus when the nominal force is the same than the traditional hydraulic press. Finally, a 6300KN cylinder-beam integrated hydraulic press, which is the first CBIHP in the world and designed by Harbin Institute of Technology (HIT) in 2012, is also introduced in this paper. It can be seen from the results of numerical simulation for the CBIHP that both of the stresses and displacements on the press in the loading process are allowable.

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.

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