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.

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

The International Sailing Canoe: A Technical Review

1994 ◽  
Vol 31 (04) ◽  
pp. 296-304
Author(s):  
Paul H. Miller ◽  
David L. Dillon
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
Factor Of Safety ◽  
Laminated Plates ◽  
Torsional Stiffness ◽  
Finite Element Analyses ◽  
Design Development ◽  
Technical Review ◽  
Construction Methods ◽  
Current Trends

The unique features of the International Sailing Canoe have intrigued naval architects and sailors for years. This paper highlights the historical design development, describes current trends, and presents results from finite element analyses of three popular construction methods: cold-molded cedar, fiberglass, and carbon/epoxy. Comparisons are presented of the bending and torsional stiffness, pitch gyradius, and factors of safety. In general, the carbon/epoxy exhibited the best characteristics, followed by the cold-molded cedar and the fiberglass. The Tsai-Wu quadratic failure criterion developed for laminated plates was used in the factor-of-safety calculations. Factors of safety correlated closely to empirical development.

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.

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.

scholarly journals Structural Integrity of Conventional and Modified Railroad Bearing Adapters for Onboard Monitoring

2014 ◽  
Author(s):  
Joseph Montalvo ◽  
Alexis Trevino ◽  
Arturo A. Fuentes ◽  
Constantine M. Tarawneh
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Element Model ◽  
Operating Conditions ◽  
Finite Element Analyses ◽  
Distribution Maps ◽  
Bearing Condition Monitoring ◽  
Monitoring Applications ◽  
Railroad Bearing ◽  
The Impact

This paper presents a detailed study of the structural integrity of conventional and modified railroad bearing adapters for onboard monitoring applications. Freight railcars rely heavily on weigh bridges and stations to determine cargo load. As a consequence, most load measurements are limited to certain physical railroad locations. This limitation provided an opportunity for an optimized sensor that could potentially deliver significant insight on bearing condition monitoring as well as load information. Bearing adapter modifications (e.g. cut-outs) were necessary to house the sensor and, thus, it is imperative to determine the reliability of the modified railroad bearing adapter, which will be used for onboard health monitoring applications. To this end, this study quantifies the impact of the proposed modifications on the adapter structural integrity through a series of experiments and finite element analyses. The commercial software Algor 20.3TM is used to conduct the stress finite element analyses. Different loading scenarios are simulated with the purpose of obtaining the conventional and modified bearing adapter stresses during normal and abnormal operating conditions. This information is then used to estimate the lifetime of these bearing adapters. Furthermore, this paper presents an experimentally validated finite element model which can be used to attain stress distribution maps of these bearing adapters in different service conditions. The maps are also useful for identifying areas of interest for an eventual inspection of conventional or modified railroad bearing adapters in the field.

Forced Response of PZT Glide Heads1

2000 ◽  
Vol 122 (4) ◽  
pp. 780-786 ◽  
Author(s):  
Jin-Hui Ou-Yang ◽  
Alex Y. Tsay ◽  
I. Y. Shen ◽  
C.-P. Roger Ku ◽  
David Kuo
Keyword(s):  
Finite Element ◽  
Impact Force ◽  
Laser Doppler Vibrometer ◽  
Forced Response ◽  
Finite Element Analyses ◽  
Pass Filter ◽  
Electric Circuits ◽  
Resonance Frequencies ◽  
Before And After ◽  
The Impact

This paper studies forced response of PZT glide heads through calibrated experiments and finite element analyses. The PZT glide heads consist of an Al2O3TiC slider and a PZT transducer. In the first part of the research, the PZT transducer serves as an actuator exciting the glide heads from 100 kHz to 1.3 MHz. A laser Doppler vibrometer (LDV) and an impedance analyzer are used to measure frequency response functions (FRF) and PZT impedance. In addition, the response of the PZT glide heads is simulated through finite element analyses (FEA). The FEA predict the resonance frequencies with less than 5 percent difference. For the first two slider modes, the FEA also predict resonance amplitudes with good accuracy. In the second part of the research, the PZT transducer serves as a sensor, and the glide head is subjected to an impact force. To produce short impacts experimentally, miniature balls are dropped to the glide heads. The impact force is estimated through the impact duration and the momentum change before and after the impact. Then the impact force and the PZT output voltage are processed to produce FRF. Since the PZT sensor and its circuit form a high-pass filter, the FEA need to consider the slider, the PZT transducer, and the electric circuits simultaneously to produce meaningful results. The FEA predictions agree with the experimental measurements for the first two slider modes as well. [S0742-4787(00)01004-3]

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