Pre-Tensioning Fixture Development for Machining of Thin-Walled Components

2011 ◽  
Vol 314-316 ◽  
pp. 319-326
Author(s):  
Jia Yuan He ◽  
Yan Wang ◽  
Nabil Gindy
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Scientific Research ◽  
Optimal Performance ◽  
Machining Process ◽  
Fixture Design ◽  
Finite Element Analyses ◽  
Machining Forces ◽  
Thin Walled ◽  
The Impact

Pre-tensioning forces are, in essence, the application of selective clamping forces on components prior to machining to create a “stress field” envelope that aids the processes of components. Utilisation of pretension forces prior to process offers advantages of increasing component rigidity, thus reducing the deflection from process, and holding the components in a way to counteract the machining forces etc. However, the scientific research of pre-tensioning forces has not been extensively or comprehensively investigated. The aim of this paper is to investigate the impact of applying pre-tensioning forces on thin walled components, and more specifically, focuses on the development of appropriate fixtures to achieve optimal performance from pre-tensioning. Finite Element Analyses (FEA) were used intensively to analyse the impact of pre-tensioning forces on components during machining process considering machining deflections. After the FE models were validated from experiments, stiffness of components under the action of pre-tensioning forces can be predicted for the development of future fixture design

Investigation of Fixture Design Exploring Pre-Tensioning Forces

2010 ◽  
Vol 97-101 ◽  
pp. 3252-3255 ◽  
Author(s):  
Jia Yuan He ◽  
Yan Wang ◽  
Nabil Gindy
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Model Validation ◽  
Fixture Design ◽  
Finite Element Analyses ◽  
Design Development ◽  
Relevant Model ◽  
Machining Forces ◽  
The Impact ◽  
Validation Experiments

Pre-tensioning forces are, in essence, the selective application of clamping forces applied prior to processess to create a “stress field” envelope that aids the processes of components. There are many potential functions of applying pre-tensioning forces, such as improvement of component rigidity, reduction of machining deflection, and holding of components to counteract the machining forces etc. However, the use of pre-tensioning forces has not been extensively and comprehensively investigated. The aim of this paper is to strengthen the understanding of the impact of applying pre-tensioning forces firstly on simple parts and specifically on the fixture design development by establishing a methodology of using pre-tensioning forces. To investigate the optimised fixture layout and clamping strategy, Finite Element Analyses (FEA) were established to show the effect of applying pre-tensioning forces on machining deflection. Meanwhile, the relevant model validation experiments were applied to verify the FEA models in this study appropriately. Eventually, the results show that the FEA simulations are sufficient and the use of pre-tensioning forces effectively reduces the machining deflection by using optimised clamping strategy.

scholarly journals A Novel Finite Element Method Approach in the Modelling of Edge Trimming of CFRP Laminates

2021 ◽  
Vol 11 (11) ◽  
pp. 4743
Author(s):  
Fernando Cepero-Mejias ◽  
Nicolas Duboust ◽  
Vaibhav A. Phadnis ◽  
Kevin Kerrigan ◽  
Jose L. Curiel-Sosa
Keyword(s):  
Finite Element ◽  
Tool Wear ◽  
Cutting Tool ◽  
Machining Process ◽  
Machining Forces ◽  
General Terms ◽  
Numerical Predictions ◽  
Composite Damage ◽  
Edge Trimming ◽  
Optimal Cutting Parameters

Nowadays, the development of robust finite element models is vital to research cost-effectively the optimal cutting parameters of a composite machining process. However, various factors, such as the high computational cost or the complicated nature of the interaction between the workpiece and the cutting tool significantly hinder the modelling of these types of processes. For these reasons, the numerical study of common machining operations, especially in composite machining, is still minimal. This paper presents a novel approach comprising a mixed multidirectional composite damage mode with composite edge trimming operation. An ingenious finite element framework which infer the cutting edge tool wear assessing the incremental change of the machining forces is developed. This information is essential to replace tool inserts before the tool wear could cause severe damage in the machined parts. Two unidirectional carbon fibre specimens with fibre orientations of 45∘ and 90∘ manufactured by pre-preg layup and cured in an autoclave were tested. Excellent machining force predictions were obtained with errors below 10% from the experimental trials. A consistent 2D FE composite damage model previously performed in composite machining was implemented to mimic the material failure during the machining process. The simulation of the spring back effect was shown to notably increase the accuracy of the numerical predictions in comparison to similar investigations. Global cutting forces simulated were analysed together with the cutting tool tooth forces to extract interesting conclusions regarding the forces received by the spindle axis and the cutting tool tooth, respectively. In general terms, vertical and normal forces steadily increase with tool wear, while tangential to the cutting tool, tooth and horizontal machining forces do not undergo a notable variation.

Optimal Clamping Scheme of Thin-Walled Cavity Workpiece

2011 ◽  
Vol 189-193 ◽  
pp. 2116-2120
Author(s):  
Shi Min Geng ◽  
Jun Wang
Keyword(s):  
Finite Element ◽  
Aluminum Alloy ◽  
Machining Process ◽  
Machining Accuracy ◽  
Finite Element Models ◽  
Thin Walled ◽  
Clamping Sequence

The thin-walled cavity workpiece with insufficient rigid property is liable to deform during the machining process and the request of accuracy is very strict. The paper takes typical aeronautic aluminum-alloy for example, fixture is an important consideration in the operation. To reveal the influences of locating points, clamping sequence and loading ways on the distortion of thin-walled cavity part, finite element models were established to simulate the clamping operation. The result shows the preferable scheme is that the distance of the clamping locations are far each other, clamping forces are firstly applied on the surface with high rigid and all clamping forces are applied in many steps. The scheme can effectively control the deformation of clamp ,and furthermore improve the machining accuracy.

Analysis of Cutting Technologies for Lightweight Frame Components

2006 ◽  
Vol 10 ◽  
pp. 121-132 ◽  
Author(s):  
Klaus Weinert ◽  
Sven Grünert ◽  
Michael Kersting
Keyword(s):  
Finite Element ◽  
Metal Cutting ◽  
Thermal Stresses ◽  
Machining Process ◽  
Frame Structure ◽  
Experimental Investigations ◽  
Promising Alternative ◽  
Thin Walled ◽  
Process Strategy ◽  
Conventional Drilling

Most technical components applied in industrial practice are subjected to metal cutting operations during their production process. However, this leads to undesirable thermal and mechanical loads affecting the machined workpiece, which can result in an impairment of its serviceability. Due to their small wall thickness lightweight hollow profiles are highly susceptible to the inevitable machining loads and thermal stresses during drilling processes. For the virtual optimization of the machining process and in order to ensure a suitable process strategy, a finite element simulation of cutting operations for thin-walled light metal profiles is conducted. Due to the flexibility within creating drill holes of different diameters without tool changes circular milling represents a promising alternative to the application of conventional drilling tools for variable process strategies to handle batch sizes down to one piece efficiently. Hence, this article gives an insight into the investigations regarding the modeling concepts of the mechanical and thermal loads induced into the thin-walled lightweight frame structure during the circular milling process. Furthermore, process reliability aspects as well as the correlation of the calculated and the measured results will be discussed on the basis of experimental investigations. Finally, this article compares Finite Element Analysis aspects of circular milling processes with conventional drilling processes.

Analyze the Impact of the Thin-Walled Hollow Pier by Construction of Reservoir

2013 ◽  
Vol 438-439 ◽  
pp. 1262-1264
Author(s):  
Ke Dong Tang ◽  
Feng Gui Jin
Keyword(s):  
Finite Element ◽  
Realistic Model ◽  
Finite Element Software ◽  
Before And After ◽  
Reservoir Construction ◽  
Thin Walled ◽  
The Impact

The river dam intends to build at 280m downstream of a built bridge. This paper, using ANSYS finite element software, establishes a rational and realistic model to analyze the influence of the reservoir construction on the thin-walled hollow pier of built bridge. The variation of the stress of the bridge thin-walled hollow pier before and after impounding of the reservoir is given out, which can be as a guidance for future reinforcing the thin-walled hollow pier.

Constraint Solutions for Cracked Plates and Cylinders

2016 ◽  
Author(s):  
Caroline Meek ◽  
Marius Gintalas ◽  
Andrew H. Sherry ◽  
Robert A. Ainsworth
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Biaxial Loading ◽  
Analytical Determination ◽  
Plastic Collapse ◽  
Finite Element Analyses ◽  
Elastic Plastic ◽  
Cracked Plates ◽  
Computing Effort

There is little advice in fitness for service procedures for assessing constraint parameters T (elastic) and Q (elastic plastic) for biaxially loaded plates and cylinders. This paper presents the analytical determination of T stresses for biaxially loaded plates and the determination of Q for plates and cylinders using finite element analyses. It demonstrates the extent to which T can be used to conservatively predict Q and how, near collapse, Q can be estimated from the stress field corresponding to plastic collapse, enabling a significant reduction in computing effort. The effect of biaxial loading of plates and cylinders on these parameters is discussed as well as the differences found when comparing the values for plates and cylinders.

Finite Element Analyses of Circumferential Cracks in Thin-Walled Cylinders: T-Stress Solutions

2006 ◽  
Author(s):  
Timothy Lewis ◽  
Xin Wang ◽  
Robert Bell
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fracture Mechanics ◽  
Fracture Analysis ◽  
Finite Element Analyses ◽  
The Finite Element Method ◽  
T Stress ◽  
Bending Loads ◽  
Pipe Radius ◽  
Thin Walled

The elastic T-stress is a parameter used to define the level of constraint at a crack tip. It is important to provide T-stress solutions for practical geometries in order to apply the constraint-based fracture mechanics methodology. In the present paper, T-stress solutions are provided for circumferential through-wall cracks in thin-walled cylinders. Cylinders with a circumferential through-wall crack were analyzed using the finite element method. Three cylinder geometries were considered; defined by the pipe radius (R) to wall thickness (t) ratios: R/t = 5, 10, and 20. The T-stress was obtained at eight crack lengths (θ/π = 0.0625, 0.1250, 0.1875, 0.2500, 0.3125, 0.3750, 0.4375, and 0.5000) for remote tension and remote bending loads. These results are suitable for constraint-based fracture analysis for cylinders with circumferential cracks.

Tank Car Puncture Analyses for Various Impactors and Impact Conditions

2013 ◽  
Author(s):  
Steven W. Kirkpatrick ◽  
Francisco Gonzalez ◽  
Karl Alexy
Keyword(s):  
Finite Element ◽  
Research Program ◽  
Impact Testing ◽  
Impact Behavior ◽  
Finite Element Analyses ◽  
Damage And Failure ◽  
Wide Range ◽  
Significant Research ◽  
Detailed Simulation ◽  
The Impact

There has been significant research in recent years to analyze and improve the impact behavior and puncture resistance of railroad tank cars. Much of this research has been performed using detailed nonlinear finite element analyses supported by full scale impact testing. This use of detailed simulation methodologies has significantly improved our understanding of the tank impact behaviors and puncture prediction. However, the evaluations in these past studies were primarily performed for a few idealized impact scenarios. This paper describes a research program to evaluate railroad tank car puncture behaviors under more general impact conditions. The approach used in this research program was to apply a tank impact and puncture prediction capability using detailed finite element analyses (FEA). The analysis methodologies apply advanced damage and failure models that were validated by series of material tests under various loading conditions. In this study, the analyses were applied to investigate the tank puncture behaviors for a wide range of impact conditions.

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