Modeling and Simulation of Optimal Blank Design and Hot Pressing Process for Manufacturing Large Francis Turbines Blades From Very Thick Plates

2013 ◽  
Author(s):  
Zhengkun Feng ◽  
Henri Champliaud ◽  
Louis Mathieu ◽  
Michel Sabourin
Keyword(s):  
Hot Pressing ◽  
Three Dimensional ◽  
High Strength ◽  
Production Costs ◽  
Francis Turbine ◽  
Thick Plates ◽  
Pressing Process ◽  
Blank Design ◽  
Cost Of Energy ◽  
Applied Forces

Hot pressing process is widely used in automotive, shipbuilding, energy production and civil engineering. However, the trial and error technique that is intensive time and energy consuming is still used. Particularly, the design of Francis turbines of hydropower plants is not standard, but variable from site to site due to hydraulic conditions and cost of energy. As a result, the blade hydraulic profile of each Francis turbine is different. The blades, one of the key components of Francis turbine runners, are produced in small batches and the setup of the dedicated punch and die increases significantly the unit production costs. In this paper, the blade unfolding process for optimal blank design will be firstly presented, and then a hot pressing process for very thick plates is proposed. The pressing process of high strength steel at hot temperature is characterized by thermo-mechanical behaviors, three-dimensional unsteady deformation, high nonlinearity, continuous local forming. The analyses of residual stress distribution and applied forces are carried out.

Analytical Modeling and FE Simulation for Analyzing Applied Forces During Roll Bending Process

2012 ◽  
Author(s):  
Hoang Quan Tran ◽  
Henri Champliaud ◽  
Zhengkun Feng ◽  
Thien-My Dao
Keyword(s):  
High Strength Steel ◽  
Plate Thickness ◽  
High Strength ◽  
Analytical Models ◽  
Francis Turbine ◽  
Roll Bending ◽  
Bending Process ◽  
Turbine Runner ◽  
Applied Forces ◽  
Corrosive Environments

High strength steel is widely used in the manufacturing of parts dealing with heavy cyclic loads and corrosive environments. However, processing this type of steel is not easy, and it becomes a hard-to-solve problem when the part to produce is large, thick and quasi-unique. One example of a thick high strength steel axisymmetric part is the conical shape of the crown of a Francis turbine runner. Some Francis turbine runners installed in the dam basement of a hydraulic power plant are 10 meters in diameter with more than 5 meters in height, while plate thickness can exceed 100 millimeters. Several processes can be envisaged for the manufacturing processes of such large parts (welding or casting…), but few processes can deliver one within a reasonable time and at competitive cost. Among them the roll bending process, causing plastic deformation of a plate around a linear axis with little or no change in plate thickness, is considered as an interesting alternative. The main objective of this research is to assess 3D dynamic finite element and analytical models for the computation of the bending forces during the manufacturing of hollow conical parts made of a thick plate and a high strength steel. Numerous parameters such as thickness, curvature, part size, material properties and friction directly influence the reaction forces on the rolls. Therefore, the results of this research provide a better understanding of the phenomena taking place in the process, and an opportunity to establish relationships between the bending forces and the parameters of a final conical part.

High strength Mg–Zn–Ca alloys prepared by atomization and hot pressing process

2014 ◽  
Vol 118 ◽  
pp. 55-58 ◽  
Author(s):  
Y.F. Zhao ◽  
J.J. Si ◽  
J.G. Song ◽  
X.D. Hui
Keyword(s):  
Hot Pressing ◽  
High Strength ◽  
Pressing Process

Simulation of Blank Design for Blades of Francis Turbines

2012 ◽  
Author(s):  
Zhengkun Feng ◽  
Henri Champliaud ◽  
Michel Sabourin ◽  
Sebastien Morin
Keyword(s):  
Casting Process ◽  
Hydropower Plant ◽  
Francis Turbine ◽  
Fe Model ◽  
Trial And Error ◽  
Pressing Process ◽  
Blank Design ◽  
Hydropower Plants ◽  
Element Approach ◽  
Numerical Modeling And Simulation

The metal pressing process which is widely used in many industries has advantages over casting process for producing large and thick blades of Francis turbine. For the design of pressing process, blank design should be firstly performed to determine the dimension of the flat blank. In fact, the traditional trial and error approach is not applicable for the blade design for Francis turbines that is not standard because of the different hydraulic characteristics of a hydropower plant from site to site. The powerful computing technology makes it possible to desgn optimum blanks by numerical modeling and simulation. In this paper, the multi-step inverse finite element approach is investigated for blank design and an elasto-plastic model has been built by using the well-known software ANSYS. Unfolding tests with cylindrical sections have been carried out and the numerical results agree well with the analytical results. Thereafter, a large and thick blade of Francis turbine for hydropower plants has been successfully unfolded by the FE model. Finally, for ensuring the machining of the blade after the pressing process, a new contour is obtained by extending the boundary of the flat blank provided by the FE model.

scholarly journals Compressive behaviours of octet-truss lattices

2020 ◽  
Vol 234 (16) ◽  
pp. 3257-3269 ◽  
Author(s):  
Yifan Li ◽  
Huaiyuan Gu ◽  
Martyn Pavier ◽  
Harry Coules
Keyword(s):  
Failure Modes ◽  
Density Ratio ◽  
Three Dimensional ◽  
Compressive Load ◽  
High Strength ◽  
Detailed Comparison ◽  
Compressive Response ◽  
Beam Elements ◽  
Structural Applications ◽  
Octet Truss

Octet-truss lattice structures can be used for lightweight structural applications due to their high strength-to-density ratio. In this research, octet-truss lattice specimens were fabricated by stereolithography additive manufacturing with a photopolymer resin. The mechanical properties of this structure have been examined in three orthogonal orientations under the compressive load. Detailed comparison and description were carried out on deformation mechanisms and failure modes in different lattice orientations. Finite element models using both beam elements and three-dimensional solid elements were used to simulate the compressive response of this structure. Both the load reaction and collapse modes obtained in simulations were compared with test results. Our results indicate that three-dimensional continuum element models are required to accurately capture the behaviour of real trusses, taking into account the effects of finite-sized beams and joints.

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

Preparation of Superhydrophobic Fabric Based on the SiO 2 @PDFMA Nanocomposites by an Emulsion Graft Polymerization and a Hot‐Pressing Process

2021 ◽  
Vol 6 (22) ◽  
pp. 5646-5654
Author(s):  
Xiaoli Liu ◽  
Youcai Gu ◽  
Tengfei Mi ◽  
Yuehua Zhao ◽  
Xiaomei Wang ◽  
...  
Keyword(s):  
Hot Pressing ◽  
Graft Polymerization ◽  
Pressing Process

Numerical Modeling of Tube Hydropiercing Using Phenomenological and Micro-Mechanical Damage Criteria

2013 ◽  
Vol 549 ◽  
pp. 172-179 ◽  
Author(s):  
Amir Hassannejadasl ◽  
Daniel E. Green
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Equivalent Plastic Strain ◽  
Mechanical Damage ◽  
High Strength ◽  
Dimensional Finite Element ◽  
Steel Dp600 ◽  
Three Dimensional Finite Element ◽  
Jc Model ◽  
Damage Criteria

Hydropiercing is an efficient way of piercing holes in mass produced hydroformed parts with complex geometries. By driving piercing punches radially into a hydroformed and fully pressurized tube, holes will be pierced and extruded into the tube-wall. Recent experimental studies have shown that the formability of advanced high strength steel (AHSS) tubes can be increased with the application of internal pressure. In this study, three-dimensional finite element simulations of a tube hydropiercing process of a dual phase steel (DP600) were performed in LS-DYNA, using phenomenological, micromechanical and combined damage criteria. Damage was included in the numerical analysis by applying constant equivalent plastic strain (CEPS), the Gurson-Tvergaard-Needleman (GTN), and the Extended GTN (GTN+JC) model. In order to calibrate the parameters in each model, a specialized hole-piercing fixture was designed and piercing tests were carried out on non-pressurized tube specimens. Of the various ductile fracture criteria, the results predicted with the GTN+JC model, such as the punch load-displacement, the roll-over depth, and the quality of the clearance zone correlated the best with the experimental data.

Stresses in Ultrasonically Assisted Turning

2006 ◽  
Vol 5-6 ◽  
pp. 351-358 ◽  
Author(s):  
N. Ahmed ◽  
A.V. Mitrofanov ◽  
Vladimir I. Babitsky ◽  
Vadim V. Silberschmidt
Keyword(s):  
Ultrasonic Vibration ◽  
Vibration Frequency ◽  
Cutting Forces ◽  
Plastic Material ◽  
Process Zone ◽  
Three Dimensional ◽  
Rate Sensitivity ◽  
High Strength ◽  
Material Model ◽  
Shear Stresses

Ultrasonically assisted turning (UAT) is a novel material-processing technology, where high frequency vibration (frequency f ≈ 20kHz, amplitude a ≈15μm) is superimposed on the movement of the cutting tool. Advantages of UAT have been demonstrated for a broad spectrum of applications. Compared to conventional turning (CT), this technique allows significant improvements in processing intractable materials, such as high-strength aerospace alloys, composites and ceramics. Superimposed ultrasonic vibration yields a noticeable decrease in cutting forces, as well as a superior surface finish. A vibro-impact interaction between the tool and workpiece in UAT in the process of continuous chip formation leads to a dynamically changing stress distribution in the process zone as compared to the quasistatic one in CT. The paper presents a three-dimensional, fully thermomechanically coupled computational model of UAT incorporating a non-linear elasto-plastic material model with strain-rate sensitivity and contact interaction with friction at the chip–tool interface. 3D stress distributions in the cutting region are analysed for a representative cycle of ultrasonic vibration. The dependence of various process parameters, such as shear stresses and cutting forces on vibration frequency and amplitude is also studied.

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