scholarly journals Motion profile calculation for freeform bending with moveable die based on tool parameters

2021 ◽  
Author(s):  
Matthias Konrad Werner ◽  
Daniel Maier ◽  
Lorenzo Scandola ◽  
Wolfram Volk
Keyword(s):  
Geometrical Model ◽  
Measured Data ◽  
Fem Simulations ◽  
Curve Fit ◽  
Starting Point ◽  
Calibration Methods ◽  
Bending Process ◽  
Calculated Curve ◽  
Continuous Feed ◽  
Motion Profile

In freeform bending the desired geometry is created by defined movements of the die while a continuous feed takes place. To compensate the differences and variations in properties of the semi-finished product, the motion profile has to be adjusted. Currently, this calibration is done once before the manufacturing process of a certain profile. Therefore, numerous iterations consisting of bending and measuring certain radii based on a default motion profile are performed. The measured data is subjected to a curve fit, which is not sufficiently suitable for all profiles and materials setups due to the fixed predefined function that is used. Furthermore, the tool setup is not taken in account. This results in wrong kinematics and production rejects. In this work, an enhanced geometrical model is introduced which incorporates tool parameters - such as distances, clearances and positioning aspects - as a starting point for further calculations. Furthermore, different calibration methods are tested and compared to each other using FEM simulations to fit the calculated curve to the actually used specimen. This work establishes the basis for further compensation and calibration strategies in order to improve the handling of varying properties of semi-finished products within the freeform bending process.

scholarly journals Bearing Capacity Model of Corroded RC Eccentric Compression Columns Based on Hermite Interpolation and Fourier Fitting

2018 ◽  
Vol 9 (1) ◽  
pp. 24 ◽  
Author(s):  
Jingzhou Xin ◽  
Jianting Zhou ◽  
Fengbin Zhou ◽  
Simon Yang ◽  
Yi Zhou
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Hermite Interpolation ◽  
Measured Data ◽  
Small Scale ◽  
Pure Bending ◽  
Eccentric Compression ◽  
Starting Point ◽  
Hermite Interpolating Polynomial ◽  
Fourier Function

With an extension in service years, bridges inevitably suffer from performance deterioration. Columns are the main components of bridge structures, which support the superstructure. The damage of pier columns is often more harmful to bridges than that of other components. To accurately evaluate the time-varying characteristics of corroded columns, this paper proposes a new model for the bearing capacity evaluation of deteriorated reinforced concrete (RC) eccentric compression columns based on the Hermite interpolation and Fourier function. Firstly, the axial compression point, the pure bending point and the balanced failure point were selected as the basic points, and the deteriorated strength of these basic points was calculated by considering factors such as concrete cracking, reduction of reinforcement area, buckling of the steel bar, bond slip and strength reduction of confined concrete. After that, the interpolation points were generated by a piecewise cubic Hermite interpolating polynomial, and the explicit expression of the interpolation points fitting function was realized by the trigonometric Fourier series model. Finally, comparison studies based on measured data from forty-five corroded RC eccentric compression columns were conducted to investigate the accuracy and efficiency of the proposed method. The results show that: (1) the prediction results for bearing capacity of corroded RC columns are in good agreement with the measured data, with the average ratio of predicted results to test results at 1.06 and the standard deviation at 0.14; (2) the proposed model unifies the three stress states of axial compression, eccentric compression and pure bending, and is consistent with the continuum mechanics characteristics; (3) the decrements of axial load carrying capacity for 10% and 50% of the corrosion rate are 31.4% and 45.2%, while in flexure they are 25.4% and 77.4%, respectively; and (4) the test data of small-scale specimens may overestimate the negative effect of corrosion on the bearing capacity of actual structures. The findings in this paper could lay a solid starting point for structural life prediction technologies based on nondestructive testing.

scholarly journals Inertial-Based Human Motion Capture: A Technical Summary of Current Processing Methodologies for Spatiotemporal and Kinematic Measures

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Benjamin R. Hindle ◽  
Justin W. L. Keogh ◽  
Anna V. Lorimer
Keyword(s):  
Data Processing ◽  
Motion Capture ◽  
Human Motion ◽  
Estimation Errors ◽  
Starting Point ◽  
Calibration Methods ◽  
Stride Rate ◽  
Device Placement ◽  
Kinematic Measures ◽  
Further Development

Inertial-based motion capture (IMC) has been suggested to overcome many of the limitations of traditional motion capture systems. The validity of IMC is, however, suggested to be dependent on the methodologies used to process the raw data collected by the inertial device. The aim of this technical summary is to provide researchers and developers with a starting point from which to further develop the current IMC data processing methodologies used to estimate human spatiotemporal and kinematic measures. The main workflow pertaining to the estimation of spatiotemporal and kinematic measures was presented, and a general overview of previous methodologies used for each stage of data processing was provided. For the estimation of spatiotemporal measures, which includes stride length, stride rate, and stance/swing duration, measurement thresholding and zero-velocity update approaches were discussed as the most common methodologies used to estimate such measures. The methodologies used for the estimation of joint kinematics were found to be broad, with the combination of Kalman filtering or complimentary filtering and various sensor to segment alignment techniques including anatomical alignment, static calibration, and functional calibration methods identified as being most common. The effect of soft tissue artefacts, device placement, biomechanical modelling methods, and ferromagnetic interference within the environment, on the accuracy and validity of IMC, was also discussed. Where a range of methods have previously been used to estimate human spatiotemporal and kinematic measures, further development is required to reduce estimation errors, improve the validity of spatiotemporal and kinematic estimations, and standardize data processing practices. It is anticipated that this technical summary will reduce the time researchers and developers require to establish the fundamental methodological components of IMC prior to commencing further development of IMC methodologies, thus increasing the rate of development and utilisation of IMC.

Velocity Optimization on Squashing and Bending Process of Large Diameter Elbow

2011 ◽  
Vol 194-196 ◽  
pp. 2204-2208
Author(s):  
Jian Zhang ◽  
Tong Mei Xiao ◽  
Liang Chu ◽  
Da Sen Bi
Keyword(s):  
Process Parameters ◽  
Large Diameter ◽  
Second Step ◽  
Fem Simulations ◽  
Bending Process ◽  
Simulation Results

FEM simulations of squashing and bending process of large diameter elbow was applied to analyze the influence of squashing velocities, one of the key process parameters, on the deformation of the tube. In this study the squashing distance of first step is 300mm after several simulation attempts, corresponding to different squashing speeds and different bending velocities of second step. The simulation results of different velocities are compared and discussed. In the end the final velocities of the two steps are given.

New Approaches to the Modal Analysis for Machine Tool Structure

1984 ◽  
Vol 106 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Shinyi Wang ◽  
Hisayoshi Sato ◽  
Masanori O-Hori
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Impulse Response ◽  
Degrees Of Freedom ◽  
Computation Time ◽  
Measured Data ◽  
Sufficient Accuracy ◽  
New Approaches ◽  
Curve Fit ◽  
Machine Tool Structure

Three new approaches to modal analysis using impulse response were developed to identify the vibration characteristics of machine tool structure. The methods are based on the principle of minimizing the sum of squares of the differences between the measured data and the analytical expression. One of the methods successfully simplified the algorithm of the curve fit procedure and the computation time was significantly economized, so that it could be carried out by a microcomputer with sufficient accuracy for the system having about 30-degrees-of-freedom.

Calibrating the APEX Model for Simulations of Environmental and Agronomic Outcomes on Dairy Farms in the Northeast U.S.: A Step-by-Step Example

2020 ◽  
Vol 36 (3) ◽  
pp. 281-301
Author(s):  
Rachel Mason ◽  
Josef Gorres ◽  
Joshua W. Faulkner ◽  
Luca Doro ◽  
Scott C. Merrill
Keyword(s):  
Crop Yields ◽  
Dairy Farm ◽  
Dairy Farms ◽  
List Type ◽  
Point Of Entry ◽  
Modeling Methodology ◽  
Decision Points ◽  
Starting Point ◽  
Calibration Methods ◽  
Apex Model

HighlightsThis article details the method used to calibrate the APEX model for simulations of dairy farm silage corn production.Useful model outputs, plots, and metrics are discussed, as well as decision points and potential improvements.The article is intended as a helpful starting point for those who are new to APEX.Abstract. This article documents the procedure used to calibrate the Agricultural Policy/Environmental eXtender (APEX) model for a project that aimed to simulate crop yields, runoff, erosion, and nutrient losses on dairy farms under climate change. We describe each step in the calibration process, presenting the model outputs, plots, and metrics that were found to be useful, and discussing the decisions that needed to be made along the way. Calibration improved the performance of the model relative to an uncalibrated “baseline” version, and 0.22 < NSE < 0.49 and PBIAS within ±12% were achieved for most of the model outputs. While the mean annual silage yield was correct (PBIAS = 2%), the model did not accurately capture year-to-year yield variations (NSE = -1.6), and results for nitrogen in runoff were poor (NSE = -0.04, PBIAS = -69%).We therefore also outline several ways in which the method could be improved. Other calibration methods exist, and the procedure presented here will not be applicable in all situations. However, fully documented APEX calibrations are rare in the literature, and the number of non-expert model users may be growing. We therefore anticipate that this paper will serve as a useful point of entry for those who are new to APEX. We also hope that this work contributes to the development of transparent and reproducible procedures for modeling studies that have real-world implications. Keywords: APEX model, Hydrologic modeling, Methodology, Model calibration.

Thermodynamic Modeling of an Epitrochoidal Engine Cycle

2013 ◽  
Author(s):  
Thomas Allen Grammer ◽  
Robert R. Bittle
Keyword(s):  
Thermodynamic Modeling ◽  
Compression Ratio ◽  
Engineering Students ◽  
Engine Performance ◽  
Measured Data ◽  
Performance Model ◽  
Discrete Models ◽  
Circular Path ◽  
Modeling Approach ◽  
Starting Point

A thermodynamic performance model has been developed for a new four-stroke piston engine design in which the crankshaft path is epitrochoidal, or non-circular. The model is based on an Otto air-standard cycle with non-ideal effects of friction, valve and spark timing, heat transfer, volumetric efficiency, and fuel burn timing then added. The same modeling approach was then used in developing a standard circular path engine model for comparison: the result being two discrete models varying only in their crankshaft paths, and thus piston path timing. The thermodynamic modeling was one phase of a larger senior design project in which senior engineering students were tasked with answering the question of whether the epitrochoidal crankshaft path engine will produce more power than a standard circular path engine of the same size and compression ratio. The starting point for the effort was the epitrochoidal crankshaft design description given in the patent, followed by major challenges of design, fabrication, modeling, and testing of a prototype engine. A Briggs and Stratton model 20 was employed as the standard circular crankshaft path comparison engine, and upon which the epitrochoidal prototype engine geometry was based. The result was two test engines of the same size and compression ratio, but differing in crankshaft path. Thermodynamic modeling, however, is the primary focus of the paper presented herein. Details of the design/fabrication/testing phases of the larger project are included in another paper, currently in preparation. The modeling description starts with the development of the mathematical equations describing the piston movement within the standard engine and the epitrochoidal engine, followed by the specifics of the thermodynamic modeling and inclusion of non-ideal effects. The model calibration to measured data is developed next, and finally a prediction of the epitrochoidal engine performance is shown to agree with measured data for the prototype engine. The testing did in fact show an increase in power in the epitrochoidal prototype engine, and the modeling was used to explain the improvements attributable to the epitrochoidal design. These results also affirmed the comparative modeling approach that was used.

Improvements to Common Data Reduction and Calibration Methods for Seven Hole Probes

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
James Crawford ◽  
A. Michael Birk
Keyword(s):  
Calibration Data ◽  
Curve Fit ◽  
Polynomial Curve ◽  
Calibration Methods ◽  
Polynomial Extrapolation ◽  
Order Polynomial ◽  
Physical Response ◽  
Probe Response ◽  
Fourth Order Polynomial ◽  
Data Sorting

The influence of calibration data sorting procedures and the order of polynomial curve fit used to calibrate seven hole pressure probes in subsonic, incompressible flow are discussed. It is shown that the inclusion of fourth order polynomial terms is necessary to properly model the physical response of the probe. It is also shown that the uniformity of probe response error is significantly affected by polynomial extrapolation near sector boundaries, and that the uniformity can be improved by using some calibration points in multiple sectors.

Improvements to Common Data Reduction and Calibration Methods for Seven Hole Probes

2012 ◽  
Author(s):  
James Crawford ◽  
A. M. Birk
Keyword(s):  
Calibration Data ◽  
Curve Fit ◽  
Polynomial Curve ◽  
Calibration Methods ◽  
Polynomial Extrapolation ◽  
Order Polynomial ◽  
Physical Response ◽  
Probe Response ◽  
Fourth Order Polynomial ◽  
Data Sorting

The influence of calibration data sorting procedures and the order of polynomial curve fit used to calibrate seven hole pressure probes in subsonic, incompressible flow are discussed. It is shown that the inclusion of fourth order polynomial terms is necessary to properly model the physical response of the probe. It is also shown that the uniformity of probe response error is be significantly affected by polynomial extrapolation near sector boundaries, and that the uniformity can be improved by using some calibration points in multiple sectors.

MATERIAL ELEMENT MODEL AND DISSIPATIVE PROCESSES FOR FERRIMAGNETIC CRYSTALS WITH A NON-EUCLIDEAN STRUCTURE

2012 ◽  
Vol 09 (03) ◽  
pp. 1250025 ◽  
Author(s):  
MARINA DOLFIN ◽  
MAURO FRANCAVIGLIA ◽  
LILIANA RESTUCCIA
Keyword(s):  
Geometric Model ◽  
Element Model ◽  
Geometrical Model ◽  
Entropy Function ◽  
Simple Material ◽  
Deformable Media ◽  
Starting Point ◽  
Material Element ◽  
The Media ◽  
Closure Conditions

In a previous paper we outlined a geometric model for the thermodynamical description of ferrimagnetic crystals with a non-Euclidean structure. Applying a geometrization technique based on a model for magnetizable deformable media earlier introduced by Maugin, starting from an appropriate dynamical system on the fiber bundle of processes for simple material elements of these media, the expressions of the entropy function and the entropy 1-form were obtained. In this contribution we deepen the study of this geometrical model. We give a detailed description of the media under consideration, we introduce the transformation induced by the process and, applying the closure conditions for the entropy 1-form, we work out the necessary conditions for the existence of the entropy function. The derivation of the entropy 1-form is the starting point to introduce an extended thermodynamical phase space. Finally, from the exploitation of the Clausius–Duhem inequality, we derive, using Maugin's techniques, the residual dissipation inequality and the heat equation in the first and second form.

scholarly journals A Tool for Predicting the Effect of the Plunger Motion Profile on the Static Properties of Aluminium High Pressure Die Cast Components

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 798 ◽  
Author(s):  
Elena Fiorese ◽  
Franco Bonollo ◽  
Eleonora Battaglia
Keyword(s):  
High Pressure ◽  
Measured Data ◽  
Chemical Compositions ◽  
Cast Aluminum ◽  
Static Properties ◽  
Cast Aluminum Alloys ◽  
Die Cast ◽  
Cold Chamber ◽  
Pressure Die Casting ◽  
Motion Profile

The availability of tools for predicting quality in high pressure die casting is a challenging issue since a large amount of defects is detected in components with a consequent worsening of the mechanical behavior. In this paper, a tool for predicting the effect of the plunger motion on the properties of high pressure die cast aluminum alloys is explained and applied, by demonstrating its effectiveness. A comparison between two experiments executed through different cold chamber machines and the same geometry of the die and slightly different chemical compositions of the alloy is described. The effectiveness of the model is proved by showing the agreement between the prediction bounds and the measured data. The prediction model proposed is a general methodology independent of the machine and accounts for the effects of geometry and alloy through its coefficients.

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