Prediction of Bend Allowance and Springback in Air Bending

2006 ◽  
Vol 129 (2) ◽  
pp. 342-351 ◽  
Author(s):  
Hyunok Kim ◽  
Ninad Nargundkar ◽  
Taylan Altan
Keyword(s):  
Computer Program ◽  
Analytical Model ◽  
Elastic Recovery ◽  
Experimental Results ◽  
Air Bending ◽  
Acceptable Accuracy ◽  
Geometric Tolerances ◽  
Plastic Elongation ◽  
Bending Process ◽  
User Friendly

In the fabrication industry, one of the critical challenges is to maintain close geometric tolerances in finished products, particularly in the air bending process. In many cases, this problem is related to springback and plastic elongation/compression of the sheet, as it undergoes deformation in bending. Springback refers to the elastic recovery of the bent sheet after unloading, whereas bend allowance refers to the elongation of the sheet during bending. Both factors, if not predicted properly, may lead to dimensional inaccuracies in the finished product and cause difficulties in the assembly. Therefore, it is essential to predict springback and bend allowance in order to obtain the final desired geometry. A new analytical model was developed to predict springback and bend allowance simultaneously in air bending, and a user-friendly computer program, BEND (Version 3.0), was developed. Results obtained from the BEND program were compared to other analytical predictions and experimental results available in the literature. It was concluded that the proposed analytical model and the computer program predicted bend allowance and springback within acceptable accuracy.

Comparison of Analytical Models of Force Prediction during Dynamic Bending Stage for 3-Roller Conical Bending Process

2014 ◽  
Vol 1016 ◽  
pp. 150-155
Author(s):  
Mahesh Chudasama ◽  
Harit K. Raval
Keyword(s):  
Shear Stress ◽  
Analytical Model ◽  
Optimum Design ◽  
Experimental Results ◽  
Analytical Models ◽  
Force Prediction ◽  
Bending Force ◽  
Bending Process ◽  
Dynamic Bending ◽  
Bottom Roller

Conical bending process using three rollers with different configurations is a widely used process for manufacturing conical sections and shells in the industries. The process involves static as well dynamic stages. For optimum design of the machine, accurate analytical model of the force prediction is required for static as well dynamic bending stages. In this paper the analytical models considering three different stress conditions have been compared with the experimental results. The observations of the comparison have been reported. It is concluded that for higher bottom roller inclination, the shear stress has to be considered for evaluation of bending force whereas for lower bottom roller inclination it can be neglected.

Simplified springback prediction of thick sandwich panel

2018 ◽  
Vol 22 (4) ◽  
pp. 1019-1038
Author(s):  
Raja Ouled Ahmed Ben Ali ◽  
Sami Chatti
Keyword(s):  
Analytical Model ◽  
Sandwich Panel ◽  
Air Bending ◽  
Bending Process ◽  
Punch Radius ◽  
Springback Prediction ◽  
Important Design ◽  
Springback Behavior ◽  
Foam Thickness ◽  
Good Agreement

Springback is one of the most important design behavior in air-bending processes. The sandwich panel exhibits more complicated bending and springback behavior due to substantial differences in mechanical properties between the foam core and the metallic skin sheet. In this paper, we will not only propose a semi-analytical model in order to easily predict springback in air-bending process of steel/polyurethane/steel sandwich panel, but also we will carry out experiments to measure springback amount. The semi-analytical model results and the experiment findings proved to be in a good agreement. In addition, numerical simulations and experiments were conducted to investigate the effects of punch radius, die opening, and the foam thickness on springback.

scholarly journals Properties and bending behavior of Nickel coated Mild steel sheet during air bending

2017 ◽  
Vol 13 (11) ◽  
pp. 5991-5996
Author(s):  
D. Pritima ◽  
P. Padmanabhan ◽  
M. Ravichandran
Keyword(s):  
Experimental Investigation ◽  
Mild Steel ◽  
Elastic Recovery ◽  
Spring Back ◽  
Forming Process ◽  
Air Bending ◽  
Punch Velocity ◽  
Bending Process ◽  
Bending Behavior ◽  
Geometrical Change

Springback refers to the elastic recovery which subject to a geometrical change when the metal undergoes deformation during the forming process. The experimental investigation of this paper is focused to analyze the behavior of spring back of nickel coated mild steel (NCMS) sheets during the air bending process. The hardeness and surface roughness was measured after coating. Experimental investigation have been conducted to resolve the influence of control parameters such as Orientations (θ), Width of the sheet (Ws), Punch travel (Tp), Holding time (Ht) and Punch Velocity (v) on spring back behavior. As a results, the incraese in Orientations, Width of the sheet, Punch travel andd Punch Velocity incraese the springback angle. 

Platform Independent Analysis of Probabilities on Multithreaded Programs

2013 ◽  
Vol 1 (3) ◽  
pp. 48-65
Author(s):  
Yuting Chen
Keyword(s):  
Operating System ◽  
Static Analysis ◽  
Main Idea ◽  
Experimental Results ◽  
Machine To Machine ◽  
Concurrent Program ◽  
Acceptable Accuracy ◽  
Multithreaded Programs ◽  
Independent Analysis ◽  
And Performance

A concurrent program is intuitively associated with probability: the executions of the program can produce nondeterministic execution program paths due to the interleavings of threads, whereas some paths can always be executed more frequently than the others. An exploration of the probabilities on the execution paths is expected to provide engineers or compilers with support in helping, either at coding phase or at compile time, to optimize some hottest paths. However, it is not easy to take a static analysis of the probabilities on a concurrent program in that the scheduling of threads of a concurrent program usually depends on the operating system and hardware (e.g., processor) on which the program is executed, which may be vary from machine to machine. In this paper the authors propose a platform independent approach, called ProbPP, to analyzing probabilities on the execution paths of the multithreaded programs. The main idea of ProbPP is to calculate the probabilities on the basis of two kinds of probabilities: Primitive Dependent Probabilities (PDPs) representing the control dependent probabilities among the program statements and Thread Execution Probabilities (TEPs) representing the probabilities of threads being scheduled to execute. The authors have also conducted two preliminary experiments to evaluate the effectiveness and performance of ProbPP, and the experimental results show that ProbPP can provide engineers with acceptable accuracy.

scholarly journals Generalized analytical model based on harmonic coupling for hybrid plasmonic modes: comparison with numerical and experimental results

2015 ◽  
Vol 23 (21) ◽  
pp. 27376 ◽  
Author(s):  
Mitradeep Sarkar ◽  
Jean-François Bryche ◽  
Julien Moreau ◽  
Mondher Besbes ◽  
Grégory Barbillon ◽  
...  
Keyword(s):  
Analytical Model ◽  
Experimental Results ◽  
Model Based

Convective Losses From Cavity Solar Receivers—Comparisons Between Analytical Predictions and Experimental Results

1983 ◽  
Vol 105 (1) ◽  
pp. 29-33 ◽  
Author(s):  
A. M. Clausing
Keyword(s):  
Experimental Data ◽  
Experimental Evidence ◽  
Analytical Model ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Refined Model ◽  
Wall Area

Cavity solar receivers are generally believed to have higher thermal efficiencies than external receivers due to reduced losses. A simple analytical model was presented by the author which indicated that the ability to heat the air inside the cavity often controls the convective loss from cavity receivers. Thus, if the receiver contains a large amount of inactive hot wall area, it can experience a large convective loss. Excellent experimental data from a variety of cavity configurations and orientations have recently become available. These data provided a means of testing and refining the analytical model. In this manuscript, a brief description of the refined model is presented. Emphasis is placed on using available experimental evidence to substantiate the hypothesized mechanisms and assumptions. Detailed comparisons are given between analytical predictions and experimental results. Excellent agreement is obtained, and the important mechanisms are more clearly delineated.

scholarly journals Adaptive Broadcasting Mechanism for Bandwidth Allocation in Mobile Services

2014 ◽  
Vol 2014 ◽  
pp. 1-14
Author(s):  
Gwo-Jiun Horng ◽  
Chi-Hsuan Wang ◽  
Chih-Lun Chou
Keyword(s):  
Analytical Model ◽  
Bandwidth Allocation ◽  
Data Dissemination ◽  
Data Access ◽  
Experimental Results ◽  
Bandwidth Utilization ◽  
Access Latency ◽  
The Mean ◽  
Access Efficiency ◽  
Broadcast Program

This paper proposes a tree-based adaptive broadcasting (TAB) algorithm for data dissemination to improve data access efficiency. The proposed TAB algorithm first constructs a broadcast tree to determine the broadcast frequency of each data and splits the broadcast tree into some broadcast wood to generate the broadcast program. In addition, this paper develops an analytical model to derive the mean access latency of the generated broadcast program. In light of the derived results, both the index channel’s bandwidth and the data channel’s bandwidth can be optimally allocated to maximize bandwidth utilization. This paper presents experiments to help evaluate the effectiveness of the proposed strategy. From the experimental results, it can be seen that the proposed mechanism is feasible in practice.

Stick-Slip, Imposition-Removal of Constraints and the Spinning Ball Problem

2000 ◽  
Vol 67 (4) ◽  
pp. 720-726
Author(s):  
S. Djerassi
Keyword(s):  
Computer Program ◽  
Experimental Results ◽  
Stick Slip ◽  
Elastic Bodies ◽  
Cyclic Motion ◽  
Ball Problem

It has been observed that balls pressed between elastic bodies spin when subjected to linear, cyclic motion. This paper proposes an explanation to this phenomenon, based upon the stick-slip theory. To this end, a modified, vectorial formulation of the stick-slip theory is presented. The formulation is applied to a model comprising a ball pressed between pairs of springs and dampers. A computer program based on this formulation is used to predict the resulting motion. Predictions are shown to agree with experimental results. [S0021-8936(01)00701-2]

scholarly journals The Roball

2002 ◽  
Vol 35 (3) ◽  
pp. 204-207 ◽  
Author(s):  
William H. Robinson
Keyword(s):  
Seismic Isolation ◽  
Inverted Pendulum ◽  
Experimental Results ◽  
Flat Plates ◽  
Isolation System ◽  
Friction Forces ◽  
New Device ◽  
System A ◽  
Full Scale Tests ◽  
User Friendly

Robinson Seismic's latest developments in seismic isolation includes a new device, the RoballTM, for seismically isolating structures during earthquakes. This advance is a new concept for seismic isolation based on the principle of the inverted pendulum. It consists of 'friction balls' or 'Roballs' moving between upper and lower spherical like cavities or flat plates. The Roballs are filled with a material which is able to provide the friction forces required to absorb the energy from numerous earthquakes while supporting the structure. The Roball technique is expected to enable light and in the future possibly heavy structures to be more economically seismically isolated. As part of a program to develop a user friendly 'seismic isolation system' a series of full-scale tests have been carried out on a number of possible designs including three approaches for vertical pressures of -1 MPa resulting in coefficients of friction of -0.1 to -0.4. In this paper we present the preliminary experimental results.

scholarly journals Experimental investigation of springback in air bending process

2018 ◽  
Vol 323 ◽  
pp. 012021
Author(s):  
Aysha Alhammadi ◽  
Hafsa Rafique ◽  
Meera Alkaabi ◽  
Jaber Abu Qudeiri
Keyword(s):  
Experimental Investigation ◽  
Air Bending ◽  
Bending Process
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