Numerical Approach for the Evaluation of Seam Welding Criteria in Extrusion Processes

2012 ◽  
Vol 504-506 ◽  
pp. 517-522 ◽  
Author(s):  
Martin Schwane ◽  
Thomas Kloppenborg ◽  
Andreas Reeb ◽  
Nooman Ben Khalifa ◽  
Alexander Brosius ◽  
...  
Keyword(s):  
Automobile Industry ◽  
Numerical Approach ◽  
Extrusion Process ◽  
Experimental Investigations ◽  
Welding Quality ◽  
Seam Welding ◽  
Numerical Investigations ◽  
Welding Line ◽  
Aluminum Profiles ◽  
Longitudinal Seam

The accurate simulation and the optimization of extrusion processes can be a helpful technique to ensure producibility of complex aluminum profiles, for example for the automobile industry. Currently, the die designing is based on expert’s knowledge and cost-intensive prototyping. The paper deals with numerical investigations based on finite element simulations as well as experimental investigations of an industrial extrusion process. A newly developed method for longitudinal seam weld prediction is applied to analyze the position of the longitudinal welding line and the welding quality.

scholarly journals Embedding of Alumina Reinforcing Elements in the Composite Extrusion Process

2008 ◽  
Vol 43 ◽  
pp. 9-16 ◽  
Author(s):  
Daniel Pietzka ◽  
Marco Schikorra ◽  
A. Erman Tekkaya
Keyword(s):  
Material Flow ◽  
Collaborative Research ◽  
Research Work ◽  
High Strength ◽  
Extrusion Process ◽  
Process Window ◽  
Experimental Investigations ◽  
Specific Behavior ◽  
Pressing Operation ◽  
Aluminum Profiles

Extruded aluminum profiles are essential for lightweight constructions in contemporary transport and automotive applications. The reinforcement of such aluminum-based profiles with high-strength materials offers a high potential for weight reduction and an improvement of functional and mechanical properties. In comparison to conventional composite extrusion using fiber or particle reinforced billets, the alternatively developed process for the embedding of endless reinforcing elements provides enormous advantages regarding extrusion forces, load-adapted reinforcement, and tool abrasion. In this extrusion process with conventional billets, modified tools with portholes are used to position reinforcing elements from outside the pressing tool and to embed them into the material flow during the pressing operation. This composite extrusion process is part of the research work started in 2003 and carried out within the scope of the Collaborative Research Center SFB/TR10. To increase the potential of composite extrusion with endless reinforcing elements, the manufacture of composite extrusion profiles with high-strength non-metallic alumina wires is planned. Due to the wires’ specific properties, e.g. high stiffness, their deflection behavior must be analyzed to guarantee a stable feeding-in process. In this paper the specific behavior of alumina reinforcing elements regarding the feeding-in process is analyzed by experimental investigations. The main influencing factors are determined and a process window is deduced.

Numerical and Experimental Investigations of the Transient Thermal Behavior of a Steam By-Pass Valve at Steam Temperatures Beyond 700 °C

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Anis Haj Ayed ◽  
Martin Kemper ◽  
Karsten Kusterer ◽  
Hailu Tadesse ◽  
Manfred Wirsum ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Power Plants ◽  
Numerical Approach ◽  
Life Assessment ◽  
Experimental Investigations ◽  
Steam Power ◽  
Steam Power Plants ◽  
Cyclic Operation ◽  
Measurement Results ◽  
Transient Thermal

Increasing the efficiency of steam power plants is important to reduce their CO2 emissions and can be achieved by increasing steam temperatures beyond 700 °C. Within the present study, the thermal behavior of a steam by-pass valve subject to cyclic operation with 700 °C steam is investigated experimentally and numerically. An innovative numerical approach was applied to predict the valve’s thermal behavior during cyclic operation, which is essential for fatigue life assessment of such a component. Validation of the applied numerical approach has shown good agreement with measurement results, indicating the potential of its application for the valve design process.

Basic Experimental and Numerical Investigations on Chip Pressing

2013 ◽  
Vol 554-557 ◽  
pp. 630-637 ◽  
Author(s):  
Martin Grüner ◽  
Marion Merklein
Keyword(s):  
Numerical Simulation ◽  
Aluminium Alloys ◽  
Testing Machine ◽  
Material Model ◽  
Extrusion Process ◽  
Milling Process ◽  
Numerical Investigations ◽  
Compression Direction ◽  
Universal Testing ◽  
The Stability

Aluminium alloys show a great potential for lightweight constructions due to their high strength and low density but the production of this material is very energy consuming. Also the recycling of aluminium alloys, e.g. chips from the milling process, shows different challenges. Beside contamination by cooling lubricant and oxidation of the surface of the chips the melting and rolling process for new semi finish products needs a high amount of energy. TEKKAYA shows a new approach for recycling of aluminium alloy chips by an extrusion process at elevated temperatures producing different kinds of profiles. A new idea is the production of components directly out of chips using severe plastic deformation for joining of the chips similar to the accumulative roll bonding process in sheet metal forming. In a first approach aluminium alloy chips out of a milling process were uniaxial compressed with different loads inside an axisymmetric tool installed in a universal testing machine. The compressed chip disks subsequently were tested with two experiments to gain information on their stability. First experiment is a disk compression test with the disk standing on its cylindrical surface, giving information on the stability perpendicular to the compression direction. Second experiment is a stacked disk compression test with three disks to investigate the stability parallel to compression direction. During all three tests force and displacement values are recorded by the universal testing machine. These data are also processed to calculate or identify input parameters for the numerical investigations. For numerical simulation ABAQUS in conjunction with the Drucker-Prager-Cap material model, which is often used for sintering processes, seems to be a good choice. By numerical simulation of the experiments and comparison with the experiments input parameters for the material model can be identified showing good accordance. This material model will be used in future numerical investigations of an extrusion process to identify tool geometries leading to high strains inside the material and by this to an increased stability of the parts.

Numerical and Experimental Investigations of Ship Maneuvers in Waves

2016 ◽  
Author(s):  
Ould el Moctar ◽  
Florian Sprenger ◽  
Thomas E. Schellin ◽  
Apostolos Papanikolaou
Keyword(s):  
Second Order ◽  
Navier Stokes ◽  
Experimental Investigations ◽  
Added Resistance ◽  
Numerical Investigations ◽  
Ship Maneuvers ◽  
Funded Project ◽  
Strong Winds ◽  
Energy Efficiency Design Index ◽  
Fundamental Requirement

Assuring a ship’s maneuverability under diverse conditions is a fundamental requirement for safe and economic ship operations. Considering the introduction of the Energy Efficiency Design Index (EEDI) for new ships and the related decreasing installed power on ships, the necessity arose to more accurately predict the maneuverability of ships in severe seas, strong winds, and confined waters. To address these issues, extensive experimental and numerical investigations were performed within the European funded Project SHOPERA. Here, second order forces and moments for a containership and a tanker were measured in model tests and computed by solving the Reynolds-Averaged Navier-Stokes (RANS) equations. Generally, these measured and computed second order loads (drift forces and yaw moments, added resistance) compared favorably. Furthermore, the effects of waves on zig-zag and turning circle maneuvers were investigated.

Theoretical and Experimental Investigation on the Flow Induced Vibrations of a Centrifugal Pump

2004 ◽  
Author(s):  
Friedrich-Karl Benra ◽  
Hans Josef Dohmen
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Transient Flow ◽  
Stokes Equations ◽  
Computer Code ◽  
Numerical Approach ◽  
Experimental Investigations ◽  
Pump Operation ◽  
Pump Rotor ◽  
Wide Range

The transport of fluids which include a lot of impurities is often done by special single-stage pumps. In order to avoid clogging of the pumps, the impellers have only one blade. This minimum blade number brings strong disadvantages during the pump operation. The rotation of the impeller in the pump casing produces a strongly uneven pressure field along the perimeter of the casing. The resulting periodically unsteady flow forces affect the impeller and produce radial deflections of the pump shaft which can be recognized as vibrations at the bearing blocks or at the pump casing. These vibrations will also be transferred to the pump casing and attached pipes. In a numerical approach the hydrodynamic excitation forces of a single-blade pump were calculated from the time dependent flow field. The flow field is known from the numerical simulation of the three-dimensional, viscous, unsteady flow in the pump by using a commercial computer code determining the Reynolds averaged Navier-Stokes equations (URANS). The periodically unsteady flow forces were computed for a complete impeller revolution. This forces affect the rotor of the pump and stimulate it to oscillations. The computed forces were defined as external forces and applied as the load on the rotor for a structural analysis. The resulting oscillations of the rotor were calculated by a transient analysis of the rotors structure using a commercial FEM-Method. To verify the calculated results, experimental investigations have been performed. The deflections of the pump rotor were measured with proximity sensors in a wide range of pump operation. Measurements of the vibration accelerations at the pump casing showed the visible effects of the transient flow. To minimize the vibration amplitudes the energizing forces have been reduced by attaching a compensation mass at the impeller. This procedure can be used as “operational balancing” of the pump rotor for a certain point of operation.

Influence Factors on the Junction Line Entering for High-Temperature Alloys in Resistance Seam Welding

2010 ◽  
Vol 34-35 ◽  
pp. 19-24
Author(s):  
Yi Ping Chen ◽  
Wen He ◽  
Fu Qiang Zhu
Keyword(s):  
High Temperature ◽  
Crack Formation ◽  
Influence Factors ◽  
Protective Measure ◽  
Welding Quality ◽  
Joint Stress ◽  
Seam Welding ◽  
High Temperature Alloys ◽  
The Common ◽  
The Stability

The junction line entering is the common flaw that has often arisen in the resistance welding, especially within the resistance seam welding for the high-temperature alloys. It decreases the effective nugget diameter and reduces the tensile-shear strength of welding joint. Stress concentration can be easily created in the junction line entering under moving loading, which induces crack formation and thus seriously affects the welding quality. Owing to the plenty of factors effect on the junction line entering as well as big difficulties for experiment and the high failure rates，junction line entering has the great significance for the stability of welding quality to study its forming and protective measure. The junction line entering for the high-temperature alloy GH163 was studied through the seam welding as follows: surface conditions, welding variables, and agitation force. Some reasonable solutions for entering were provided.

Seam Weld Positioning for Composite Extrusion

2006 ◽  
Vol 10 ◽  
pp. 101-110 ◽  
Author(s):  
Marco Schikorra ◽  
Matthias Kleiner
Keyword(s):  
Material Flow ◽  
Base Material ◽  
Extrusion Process ◽  
Velocity Fields ◽  
Experimental Investigations ◽  
Local Perturbation ◽  
Seam Weld ◽  
Element Simulation ◽  
Development Area

The production of continuously reinforced profiles by use of aluminium as base material and a reinforcement made of steel or carbon offers a great potential for modern lightweight constructions. Within this scope, they present the potential for an increase in usage of space frame constructions in automotive or aerospace engineering. But with the insertion of reinforcement in the material flow of the extrusion process some problems can occur that are negligible in thee conventional extrusion processes: in the composite development area a significant local perturbation of the material flow is induced that can lead to the induction of high tensile stresses into the reinforcement. Due to this, failures like cracking of the reinforcement elements during the extrusion process has been detected in experimental investigations. A second problem occurring is the necessity of prediction of the seam weld position and prediction of the seam weld quality. The reinforcement can only be induced by bridge dies between two strands and due to this it is always positioned in a seam weld. While in conventional extrusion the seam weld positions is often only an aesthetical problem, now this position mainly influences the extruded profiles properties like moment of inertia. This paper deals with the problem of determination of seam weld position on the example of a double-t-profile extrusion. By use of a coupled thermo-mechanical finite element simulation with the commercial FE code HyperXtrude from Altair the velocity fields of an extrusion process with and without reinforcement were calculated and the resulting material flow was analysed. The numerical results went along with experimental investigations to verify the calculated results.

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