Influence of Friction on the Loads in a Roll Forming Simulation with Compliant Rolls

2014 ◽  
Vol 611-612 ◽  
pp. 436-443 ◽  
Author(s):  
Christian Mueller ◽  
Xun Gu ◽  
Lars Baeumer ◽  
Peter Groche
Keyword(s):  
State Of The Art ◽  
Simulation Models ◽  
Roll Forming ◽  
Forming Process ◽  
Friction Behavior ◽  
Friction Coefficients ◽  
Forming Simulation ◽  
Compliance Behavior ◽  
Complex Measurement

Roll forming is an important economic forming process for manufacturing of profiles. For an optimal design of the process, it is important to determine the loads occurring during the forming process. Furthermore, the information of the load behavior enables an evaluation of the formability of the planned profiles with the chosen roll forming machine. An experimental determination of loads in roll forming processes requires a complex measurement setup in combination with a high amount of measurement devices. Hence, the analysis of roll loads by means of finite element simulation is of special interest. The use of roll forming simulations for the determination of geometrical outputs is state of the art. However, due to simplifications, a realistic and reliable output of roll loads in roll forming is impossible. Therefore, the compliance behavior under load and the frictional behavior have to be incorporated in the simulation model. The friction behavior in roll forming processes is presented to be very insignificant in literature. The value of the friction coefficients vary in a broad range. Due to lack of knowledge in the compliance behavior of the used stands, simulation models with rigid rolls are still state of the art. This paper will show the reproduction of realistic roll loads, e.g. torques and forces, in a roll forming simulation. Therefore, the friction coefficients of each roll-sheet metal contact will be gained experimentally and implemented in the numerical model. Furthermore, a characteristic compliance of the roll forming stands will be analyzed and also considered in the simulation. Finally, the influence of changing parameters, e.g. raise of the friction coefficients, on the roll loads will be investigated. To verify the simulation the numerical results will be compared to data gained by experiments.

Verification of Numerical Roll Forming Loads with the Aid of Measurement Equipment

2014 ◽  
Vol 939 ◽  
pp. 373-380 ◽  
Author(s):  
Peter Groche ◽  
Christian Mueller ◽  
Lars Baeumer
Keyword(s):  
Numerical Model ◽  
Process Design ◽  
Mass Production ◽  
Roll Forming ◽  
Measurement Equipment ◽  
Forming Process ◽  
Forming Simulation ◽  
Roll Forming Process

Roll forming is an important forming process for profile manufacturing in mass production. The design of the process has an important influence on the quality of the products. Therefore, the knowledge of the occurring loads during the roll forming process, e.g. forces and pressures, is essential for the process design. However, the experimental determination of the occurring contact normal pressures in roll forming processes poses a challenge. Finite element simulations offer the potential to approximate contact normal loads and thus, enable a better process design. Nevertheless, due to simplifications of the numerical model, a realistic and reliable output of loads in roll forming is not possible. An enhanced numerical model could provide more valuable information. This paper will demonstrate the reproduction of realistic contact normal pressures and load forces in a roll forming simulation. To verify the numerical values, they will be compared to data gained by experiments.

Solid Shell Element and its Application in Roll Forming Simulation

2007 ◽  
Vol 340-341 ◽  
pp. 347-352 ◽  
Author(s):  
Da Yong Li ◽  
Ying Bing Luo ◽  
Ying Hong Peng
Keyword(s):  
Degrees Of Freedom ◽  
Shell Element ◽  
Element Model ◽  
Roll Forming ◽  
Good Prospect ◽  
Solid Shell ◽  
Forming Process ◽  
Forming Simulation ◽  
Assumed Natural Strain ◽  
Roll Forming Process

Solid shell element models which possess only translational degrees of freedom and are applicable to thin structure analyses has drawn much attention in recent years and presented good prospect in sheet metal forming. In this study, a solid shell element model is introduced into the dynamic explicit elastic-plastic finite element method. The plane stress constitutive relation is assumed to relieve the thickness locking and the selected reduced integration method is used to overcome volumetric locking. The assumed natural strain method is adopted to resolve shear locking and trapezoidal locking problem. Two benchmark examples and a stage of roll forming process are calculated, and the calculating results are compared with those by solid element model, which demonstrates the effectiveness of the element.

Study on the Spring-Back Effect with Stress Distribution According to Forming Sheet Width in the Roll Forming Process

2015 ◽  
Vol 789-790 ◽  
pp. 116-120
Author(s):  
Dong Hong Kim ◽  
Hao Yu ◽  
Dong Won Jung
Keyword(s):  
Stress Distribution ◽  
Roll Forming ◽  
Spring Back ◽  
Forming Process ◽  
Element Analysis ◽  
Forming Simulation ◽  
Sheet Width ◽  
Simulation Results ◽  
The Relationship ◽  
Roll Forming Process

This study, based on finite element analysis, analyzed the spring back phenomenon and stress distribution of forming sheets (HTS) in the roll forming process. By comparison of the stress distribution, this study analyzed two kinds of simulation. The first simulation performed simple bending simulation before roll forming simulation. With reference to the first simulation results, the second simulation analyzed the relationship between the stress distribution and the phenomenon of spring back. We also studied the stress distribution effect for spring back in the forming sheet.

scholarly journals Experimental and Numerical Determination of the Local Fiber Volume Content of Unidirectional Non-Crimp Fabrics with Forming Effects

2019 ◽  
Vol 3 (1) ◽  
pp. 19 ◽  
Author(s):  
Siegfried Galkin ◽  
Eckart Kunze ◽  
Luise Kärger ◽  
Robert Böhm ◽  
Maik Gude
Keyword(s):  
Volume Content ◽  
Fiber Orientation ◽  
Detailed Knowledge ◽  
Transverse Compression ◽  
Forming Process ◽  
Fiber Volume ◽  
Forming Simulation ◽  
Draping Simulation ◽  
Local Fiber

Detailed knowledge of the local fiber orientation and the local fiber volume content within composite parts provides an opportunity to predict the structural behavior more reliably. Utilizing forming simulation methods of dry or pre-impregnated fabrics allows for predicting the local fiber orientation. Additionally, during the forming process, so-called draping effects like waviness, gapping or shear-induced transverse compression change the local fiber volume content. To reproduce and investigate such draping effects, different manufacturing tools have been developed in this work. The tools are used to create fabric samples with pre-defined deformation states, representing the different draping effects. The samples are evaluated regarding the resulting fiber volume content. The experimental results are compared with the predictions of an analytical solution and of a numerical solution based on draping simulation results. Furthermore, the interaction of the draping effects at arbitrary strain states is discussed regarding the resulting fiber volume content.

Bestimmung der Zuschnittslänge beim Walzprofilieren von Kaltprofilen*/Calculation of initial sheet width in roll forming

2015 ◽  
Vol 105 (10) ◽  
pp. 709-714
Author(s):  
P. Groche ◽  
T. Traub ◽  
H. Dridi ◽  
L. A. Falcon
Keyword(s):  
State Of The Art ◽  
Calculation Model ◽  
Roll Forming ◽  
Calculation Methods ◽  
Reliable Determination ◽  
Blank Sheet ◽  
Sheet Width ◽  
Stand Der Technik ◽  
Numerous Calculation

Ein wesentlicher Schritt in der Produktionsplanung von walzprofilierten Kaltprofilen besteht in dem Ermitteln der Breite des benötigten Coils. Im Stand der Technik lassen sich hierzu zahlreiche Methoden finden, die sich in ihren Prognosen jedoch widersprechen und somit keine zuverlässige Bestimmung der abgewickelten Länge erlauben. Diese Arbeit zeigt einen Weg auf, wie durch experimentelle Versuche eine verbesserte Methode zum Bestimmen der abgewickelten Länge abgeleitet werden kann.   Determining the dimension of the initial blank sheet is a crucial step in planning roll forming processes. The state of the art provides numerous calculation methods for this, leading to different results and thus preventing the reliable determination of the unfolded length. This paper presents an approach for developing an improved calculation model for determining the initial sheet width by experimental analysis.

Experimental and Numerical Determination of the Required Initial Sheet Width in Die Bending

2015 ◽  
Vol 639 ◽  
pp. 147-154 ◽  
Author(s):  
Tilman Traub ◽  
Peter Groche
Keyword(s):  
Numerical Simulations ◽  
State Of The Art ◽  
Roll Forming ◽  
Material Strength ◽  
Calculation Methods ◽  
Metal Sheets ◽  
High Measurement ◽  
Sheet Width ◽  
Numerous Calculation

So far, determining the necessary precut dimensions of metal sheets prior to bending has been an unsolved question. During the last decades numerous calculation methods have been suggested. However, comparing these different methods indicates that different calculation methods suggest diverging precut dimensions. Especially in roll-forming, where multiple bend operations occur within the same bend part, these differences between several calculation methods can add up to some millimetres. The accuracy of presently available methods can hardly be compared. Thus an optimized method is needed. One possibility to determine the initial sheet width is identifying the position of the unlengthened layer in the bend zone. This study compares the position of the unlengthened layer determined in experiments and numerical simulations for different bend geometries and materials. The results indicate that even state of the art measuring technique is not accurate enough to determine the position of the unlengthened layer properly. Due to high measurement uncertainties, numerical simulations are required to assess the influence of geometry or material parameters on the position of the unlengthened layer. However, combining numerical and experimental results shows that the geometry of the bend part influences the position of the unlengthened layer and thus the required precut dimension. In contrast, a significant influence of material strength on the position of the unlegthened layer was not found.

Investigation of a Geometrical Base Parameter Affecting on Bending Quality in a Thin Sheet Metal

2017 ◽  
Vol 728 ◽  
pp. 66-71
Author(s):  
Aran Blattler ◽  
Maitri Kamonrattanapisud ◽  
Thanasan Intarakumthornchai ◽  
Yingyot Aue-u-Lan
Keyword(s):  
Sheet Metal ◽  
Thin Sheet ◽  
Fem Simulation ◽  
Roll Forming ◽  
Forming Process ◽  
Bending Process ◽  
Thin Sheet Metal ◽  
Bending Radius

A geometrical base parameter is investigated to determine the effect on a bending quality of a thin sheet metal for a roll forming process. This parameter is usually used as a criterion for the quality control of incoming materials for the bending process. This study was conducted by using a FEM simulation. The determination of the geometrical base parameter is considered as an appropriate and unique characteristic for each type of materials. To find this geometrical base parameter the dimensions of the workpiece must be measured while loading. The sensitivity of the bend allowance of a sheet metal is dependent on this geometrical base parameter. The high geometrical base parameter is led to indicate the elongation and the strength of the material. The principles of the geometrical base parameter are dependent on several factors, such as the bending angle, bending radius, material thickness, bend allowance, bending types and mechanical properties of materials. The outcomes of this study could provide the information used to enhance the bend quality of the sheet metal.

scholarly journals The Degree of Oxidation of Graphene Oxide

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 560
Author(s):  
Alexandra Carvalho ◽  
Mariana C. F. Costa ◽  
Valeria S. Marangoni ◽  
Pei Rou Ng ◽  
Thi Le Hang Nguyen ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Ab Initio ◽  
State Of The Art ◽  
High Accuracy ◽  
Precise Determination ◽  
Photoemission Spectroscopy ◽  
Pristine Graphene ◽  
X Ray ◽  
Degree Of Oxidation

We show that the degree of oxidation of graphene oxide (GO) can be obtained by using a combination of state-of-the-art ab initio computational modeling and X-ray photoemission spectroscopy (XPS). We show that the shift of the XPS C1s peak relative to pristine graphene, ΔEC1s, can be described with high accuracy by ΔEC1s=A(cO−cl)2+E0, where c0 is the oxygen concentration, A=52.3 eV, cl=0.122, and E0=1.22 eV. Our results demonstrate a precise determination of the oxygen content of GO samples.

scholarly journals New Equation for Predicting Pipe Friction Coefficients Using the Statistical Based Entropy Concepts

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 611
Author(s):  
Yeon-Woong Choe ◽  
Sang-Bo Sim ◽  
Yeon-Moon Choo
Keyword(s):  
Friction Coefficient ◽  
Accurate Determination ◽  
Mean Velocity ◽  
Friction Coefficients ◽  
Flow Discharge ◽  
Comparison Results ◽  
Flow Loss ◽  
Key Variables ◽  
New Equation

In general, this new equation is significant for designing and operating a pipeline to predict flow discharge. In order to predict the flow discharge, accurate determination of the flow loss due to pipe friction is very important. However, existing pipe friction coefficient equations have difficulties in obtaining key variables or those only applicable to pipes with specific conditions. Thus, this study develops a new equation for predicting pipe friction coefficients using statistically based entropy concepts, which are currently being used in various fields. The parameters in the proposed equation can be easily obtained and are easy to estimate. Existing formulas for calculating pipe friction coefficient requires the friction head loss and Reynolds number. Unlike existing formulas, the proposed equation only requires pipe specifications, entropy value and average velocity. The developed equation can predict the friction coefficient by using the well-known entropy, the mean velocity and the pipe specifications. The comparison results with the Nikuradse’s experimental data show that the R2 and RMSE values were 0.998 and 0.000366 in smooth pipe, and 0.979 to 0.994 or 0.000399 to 0.000436 in rough pipe, and the discrepancy ratio analysis results show that the accuracy of both results in smooth and rough pipes is very close to zero. The proposed equation will enable the easier estimation of flow rates.

scholarly journals Characterization and Quantification of Selenoprotein P: Challenges to Mass Spectrometry

2021 ◽  
Vol 22 (12) ◽  
pp. 6283
Author(s):  
Jérémy Lamarche ◽  
Luisa Ronga ◽  
Joanna Szpunar ◽  
Ryszard Lobinski
Keyword(s):  
Mass Spectrometry ◽  
State Of The Art ◽  
Animal Health ◽  
Primary Standard ◽  
Selenoprotein P ◽  
Primary Standards ◽  
Analytical Approaches ◽  
Careful Investigation ◽  
Accurate Quantification

Selenoprotein P (SELENOP) is an emerging marker of the nutritional status of selenium and of various diseases, however, its chemical characteristics still need to be investigated and methods for its accurate quantitation improved. SELENOP is unique among selenoproteins, as it contains multiple genetically encoded SeCys residues, whereas all the other characterized selenoproteins contain just one. SELENOP occurs in the form of multiple isoforms, truncated species and post-translationally modified variants which are relatively poorly characterized. The accurate quantification of SELENOP is contingent on the availability of specific primary standards and reference methods. Before recombinant SELENOP becomes available to be used as a primary standard, careful investigation of the characteristics of the SELENOP measured by electrospray MS and strict control of the recoveries at the various steps of the analytical procedures are strongly recommended. This review critically discusses the state-of-the-art of analytical approaches to the characterization and quantification of SELENOP. While immunoassays remain the standard for the determination of human and animal health status, because of their speed and simplicity, mass spectrometry techniques offer many attractive and complementary features that are highlighted and critically evaluated.

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