Benny Ørtoft Endelt

Benny Ørtoft Endelt
Aalborg University · Department of Mechanical and Manufacturing Engineering

Ph.D

About

62
Publications
12,390
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411
Citations
Introduction
The majority of my research activities are based on the ability to model and simulate complex nonlinear manufacturing processes (typical metal forming problems modeled in LS-DYNA) - the development of accurate finite elements models can be both challenging and rewarding work. However, I find it more interesting to focus on the new opportunities they open with respect to formulate and solve academic and engineering problems which are otherwise impossible to model or solve using classical methods.

Publications

Publications (62)
Article
Full-text available
Metal forming processes in general can be characterised as repetitive processes; this work will take advantage of this characteristic by developing an algorithm or control system which transfers process information from part to part, reducing the impact of repetitive uncertainties, e.g. a gradual changes in the material properties. The process is h...
Article
The performance of a feedback control system is often limited by the quality of the model on which it is based, and often the controller design is based on trial and error due to insufficient modeling capabilities. A framework is proposed where the controller design is based on classical state space control theory and time series. The system plant...
Conference Paper
Full-text available
Feedback control of sheet metal forming operations has been an active research field the last two decades and highly advanced control algorithms have been proposed - controlling both the total blank-holder force and in some cases also the distribution of the blank-holder force. However, there is a number of obstacles which need to be addressed befo...
Conference Paper
Full-text available
Tube hydro-forming has a broad industrial appeal as the process enables production of geometrically complex parts within a single forming operation. The process is highly flexible with respect to adjustable process parameters (in the present context trajectories for the internal pressure and axial feeding). The filling of the tool is controlled by...
Article
This work deals with the identification of parameters for constitutive models by inverse modeling. This is a topic which has been of increasing interest among researcher within the sheet metal forming community. A method for analytical sensitivity analysis is presented and a non-linear least square technique is used to solve the inverse problem, i....
Article
Full-text available
The present work will address the problem of designing an in-process control system for a tube hydro-forming process, controlling the tool filling forming a T-tube. The control problem is nontrivial as wrinkling and bursting will develop rapidly and, in most cases, are irreversible—thus, the control system must react fast and without extensive over...
Article
Full-text available
A T-shape tube hydraulic bulge test under axial feeding force is carried out to characterize the mechanical properties of EN AW 5049-O and 6060-O aluminium alloys. The punch displacement, T-branch height and axial compressive force are recorded online during the experiment. An intelligent inverse identification framework combining the finite elemen...
Article
Full-text available
This paper is to determine the flow stress curve of 5049-O aluminium alloy by a tube hydraulic bulging test with fixed end-conditions. During this test, several tubular specimens are bulged under different internal pressures before their bursting, and the corresponding bulging height and wall thickness at the pole are measured. An inverse strategy...
Conference Paper
An automatic inverse framework has been developed to determine constitutive parameters of tubular materials in metal forming processes. It combines finite element simulations and optimization techniques and allows a more accurate parameter identification by eliminating geometrical and mechanical assumptions of classical analytical models. During th...
Article
Full-text available
The paper presents a hybrid strategy to determine constitutive parameters for thin-walled tubes based on experimental responses from hydraulic bulge tests. This developed procedure integrates the analytical model, finite element analysis and gradient-based optimization algorithm, where initial guesses of material parameters are generated quickly by...
Conference Paper
Full-text available
Tube hydraulic bulging tests with fixed-end conditions are carried out to explore tubular material characteristics for 5049 aluminium. Tube diameter at the center of specimen and pole thickness under different internal pressures are recorded during forming process. Based on experimental data, two types of theoretical models using membrane mechanics...
Article
Grain refinement and the avoidance of columnar solidification is a great challenge in the deep penetration laser welds of thick-section steels. Further knowledge about the heat distribution and the temperature gradients in laser welds is vital for future attempts on the grain refinement of such welds. In this study, a comparative investigation was...
Article
Full-text available
The laser forming process is characterized by high temperature gradients and localized deformation. The process uses a laser to introduce thermal strains. The localized deformation along with the high temperature gradients is introduced iteratively which creates a complex and dynamic forming process. To understand the dynamic behavior of the proces...
Article
Full-text available
Laser forming is a non-contact forming method. By control of different process parameters, different forming mechanisms can be achieved. The forming mechanisms allows for bending, compression and buckling. Process control to ensure correct combination and usage of each forming mechanism is still an open issue. Present work is an attempt to implemen...
Article
Full-text available
The interest in accurate prediction of failure of sheet metals in the automotiveindustry has increased significantly over the last two decades. This paper aims to evaluate two failure prediction approaches implemented in the commercial Finite Element code AutoFormplus R7.04; (i) the standard Forming Limit Diagram (FLD), and (ii) the Non-linear Form...
Conference Paper
Full-text available
Ensuring process feasibility is a high priority in the automotive industry today. Within the CAE departments concerning the manufacturing of body components, one of the most important areas of interest is the accurate prediction of failure in components through Finite Element simulations. This paper investigates the possibility of introducing the c...
Conference Paper
Full-text available
Over the last two decades there has been an increasing academic and industrial focus on process robustness and process control applied on sheet-metal forming processes and a high number of control schemes have been proposed. However, many of the proposed control schemes rely on process data sampled during the punch stroke (in case of stamping and d...
Article
Understanding the disturbances introduced by cavitation inside spray nozzles is important, when simulating the spray formation of highly viscous liquids. In this paper, a new model for cavitation-induced primary break-up is proposed, which is able to map the influence of cavitating nozzle flow on spray formation. Detailed experimental and numerical...
Article
Full-text available
The quality of robotic laser welded parts is related to the joint location, the trajectory of the laser focal point and the process parameters. By performing in-process monitoring, it is possible to acquire sufficient process knowledge for post-inspection to evaluate the geometrical weld quality. The existing solutions for such systems operate alon...
Article
Full-text available
Laser forming is a process capable of bending sheet metal only with the laser beam and without a physical interaction with the part. The part is formed by small and local deformations by the laser beam and it is done in increments with each pass of the laser. This incremental forming makes it difficult to ensure a smooth deformation field, which ca...
Article
Full-text available
Feedback and process control of metalforming processes has received increasing attention the lastdecade. Basically there exist four control philosophies; control ofprocess parameters during the punch stroke, iterative learning control(based on historical data), a combination iterative learning andfeedback control and finally feed-forward control. T...
Article
Full-text available
Full and partial penetration welding using high power lasers exhibit different melt pool geometries. The main difference is that full penetration welds tend to widen at the root side. In recent years, full penetration laser welding has been modeled using sophisticated multiphase numerical models. However, less computationally-complex thermo-mechani...
Article
Full-text available
A newly proposed method for the manufacturing of sheet metal parts with very small radii is the bulging-pressing compound-forming process (Wang et al. Chin J Eng 39:1077–1086, 2017). The principle of this method is introduced, and the key process parameters such as the hydraulic pressure loading path, punch velocity, and initial punch position are...
Article
Full-text available
Edge effects in laser forming influence the possible tolerances that can be achieved with laser forming. Edge effects arise due to uneven temperature profiles along the laser scan line. It has been suggested that an increased cooling rate can minimize the occurrence of edge effects. This work will examine the effect of increased cooling to reduce e...
Article
Laser forming of sheet metal has the potential to add to the growing repertoire of laser processing. This is of particular interest for flexible manufacturing and rapid prototyping. A factor limiting the practical use is the planning of the process parameters, such as laser scan path, laser power, laser scan speed, laser spot size, dwell time, etc....
Article
Full-text available
Forming operation are subject to external disturbances and changing operating conditions e.g. new material batch, increasing tool temperature due to plastic work, material properties and lubrication is sensitive to tool temperature. It is generally accepted that forming operations are not stable over time and it is not uncommon to adjust the proces...
Article
Purpose The purpose of this study is to investigate the rheological behavior of commercial lubrication oils used for cylinder lubrication in two-stroke marine diesel engines. Furthermore, it is of interest to investigate if the viscosity of lubrication oils is affected by different levels of alkalinity. Design/methodology/approach Viscosity meas...
Conference Paper
Full-text available
Forming operation are subject to external disturbances and hanging operating conditions e.g. new material bat h, increasing tool temperature due to plasticwork, material properties and lubrication is sensitive to tool temperature. It is generally accepted that forming operations are not stable over time and it is not uncommon to adjust the pro ess...
Article
Full-text available
This paper presents results from application of discrete state spacebased feedback control of the blank holder force (BHF) magnitude and distribution in the drawing ofa rectangular workpiece. By means of monitoring the flange draw-in during the punch stroke, the controller makes continuousadjustments to the BHF magnitude and distribution by individ...
Conference Paper
This paper investigates process control possibilities obtained from a new tool concept for adaptive blank holder force (BHF) distribution. The investigation concerns the concept’s application to a multi-step deep drawing process exemplified by the NUMISHEET2014 benchmark 2: Springback of draw-redraw pan. An actuator system, where several cavities a...
Article
Full-text available
Tube hydroforming has a broad industrial appeal as the process enables production of geometrically complex parts within a single forming operation. The process is highly flexible with respect to adjustable process parameters (in the present context trajectories for the internal pressure and axial feeding). The objective of the present work is to id...
Article
In deep drawing, the strain path in the blank during the forming process can be significantly affected by application of temporal and spatial variation of the blank holder force. In this study, an active tool system capable of controlling the distribution of the blank holder force is presented which can be integrated into existing stacked deep draw...
Article
Full-text available
Metal forming processes can general be characterized as repetitive processes, this work will take advantage of this characteristic by developing an algorithm or control system which transfers process information from part to part, reducing the impact of long term disturbances e.g. a gradual changes in the material properties. KeywordsMachine learn...
Article
Full-text available
A five stage forming strategy for Single Point Incremental Forming of a circular cylindrical cup with a height/radius ratio of one is presented. Geometrical relations are discussed and theoretical strains are calculated. The influence of forming direction (upwards or downwards) is investigated for the second stage comparing explicit FE analysis wit...
Article
Full-text available
The paper will investigate the robustness of a feedback control system subject to normal distributed noise. The feedback control system is applied on a square deep drawing where the flange draw-in is used as state variables and the flange draw-in is controlled using a distributed blank-holder force.
Article
This paper demonstrates the use of an intelligent shimming system to compensate for changes in process output due to tool wear. A new tool concept with integrated hydraulic cavities used as actuators in feedback control system is presented. By prescribing a hydraulic pressure in the individual cavities the blank-holder force distribution can be con...
Article
Full-text available
A new tool design concept for deep drawing is presented. The design features a hydraulic shimming system providing a variable blank holder force (BHF). An objective function describing the geometric quality of the drawn part and the process stability is formulated. The objective function is used in a gradient based optimization scheme to find a set...
Article
Full-text available
We investigated if injectable calcium phosphate cement improves primary stability in open-wedge high-tibial osteotomy. A 10 mm open-wedge osteotomy was performed on eight pairs of preserved cadaver tibiae and seven pairs of composite (Sawbone) left tibiae. Osteosynthesis was performed with the Dynafix plate system. The gap resulting from surgery ei...
Conference Paper
Full-text available
Long precision tubes are commonly made using the floating plug tube drawing process. The process has been analyzed using various methods e.g. upper bound method and FEM [1-10]. The die land and the plug land are usually cylindrical and form a cylindrical bearing channel between the die land and the plug land. The influence from the length of the be...
Conference Paper
Full-text available
Various strategies for on-line feedback control for forming operations have been proposed, e.g. expert and database systems, response surface, neural network etc. This paper presents a framework for the design of controllers for highly non-linear systems; the framework is inspired by classical state space control theory combined with a non-linear f...
Conference Paper
Full-text available
The drawing of an aluminium tube from Ø32*1.2 mm to Ø30*1.0 mm using a floating plug has been analysed using FEM-simulations. The die and the plug usually have a cylindrical section denoted die land and plug land, respectively. The FEM simulations show that is has a significant influence on the drawing force if the die land or plug land instead of...
Conference Paper
Full-text available
A material model with shear rate and, optionally, temperature dependent viscosity was implemented. Shear rate dependence is expressed with a Yasuda function and temperature dependence with an Arrhenius function. The functions were fitted to viscosity data from oscillatory rheometry of polystyrene. Validation of the viscosity function in the materia...
Article
By using aluminum alloys, the properties of the material in sheet hydroforming were obtained based on the identification of parameters for constitutive models by inverse modeling in which the friction coefficients were also considered in 2D and 3D simulations. With consideration of identified simulation parameters by inverse modeling, some key proc...
Article
Although sheet hydroforming has gained increasing interest in the world, it is difficult to determine the optimal forming parameters in FEM due to the incorrect application of material property parameters. In this paper, the properties of the material used in sheet hydroforming were obtained to meet the reality based on the identification of parame...
Article
Various strategies for on-line feedback control for forming operations have been proposed, e.g. expert and database systems, response surface, neural network, etc. The paper presents a new framework for the design of controllers for highly non-linear systems, the framework is based on classical state space control theory combined with a non-linear...
Article
Full-text available
The dominating material test for sheet metal is the uni-axial tensile test, the test does however, cover a very limited deformation-range. The demand for alternative identication schemes for identication of constitutive parameters is getting more pronounced as the complexity of the constitutive equations is increasing i.e. the number of parameters...
Article
Full-text available
The computational‐costs for finite element simulations of general sheet metal forming processes are considerable, especially measured in time. In combination with optimization, the performance of the optimization algorithm is crucial for the overall performance of the system, i.e. the optimization algorithm should gain as much information about the...
Article
Full-text available
The demand for alternative identification schemes for identification of constitutive parameters is getting more pronounced as the complexity of the constitutive equations increases, i.e. the number of parameters subject to identification. A general framework for inverse identification of constitutive parameters associated with sheet metal forming i...
Article
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The automotive industry currently uses rubber hoses as the media carrier between e.g. the radiator and the engine, and the basic idea is to replace the rubber hoses with flexible aluminum tubes.
Thesis
Full-text available
The major subject of the thesis is nonlinear least square optimization techniques, identification of constitutive parameters through inverse modeling and process/product optimization. The application area throughout the thesis will be sheet metal forming. The sheet metal forming domain is highly matured with respect to quality and stability of simu...
Article
Full-text available
Summary This article deals with the identification of parameters for constitutive models by inverse modeling. A non-linear least square technique was used to solve the inverse problem, i.e. minimize the least-square error between a experimental and a model data-set. The scheme was tested on synthetic data, involving deep drawing of a symmetric roun...

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Projects

Projects (3)
Project
Development of a machine to manufacture metal parts faster and cheaper. The technology will potentially reduce handling time, change over time, need of storage, machine space, throughput time, programming time and equipment investment.
Project
This is an ongoing "pet project" of mine, where the overall goal is to develop robust and stable control algorithms which can be applied on sheet-metal operations i.e. deep-drawing and stamping.
Project
Experimental implementation and verification of a feedback system, controlling the filling of the tool cavity in a T-tube.