scholarly journals Mastering Yield Stress Evolution and Formwork Friction for Smart Dynamic Casting

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2084
Author(s):  
Anna Szabo ◽  
Lex Reiter ◽  
Ena Lloret-Fritschi ◽  
Fabio Gramazio ◽  
Matthias Kohler ◽  
...  
Keyword(s):  
Yield Stress ◽  
New Technologies ◽  
Slip Casting ◽  
Digital Fabrication ◽  
Process Window ◽  
Process Conditions ◽  
Forming Process ◽  
Start Time ◽  
Strength Evolution ◽  
Folded Structures

The construction industry is a slow adopter of new technologies and materials. However, interdisciplinary research efforts in digital fabrication methods with concrete aim to make a real impact on the way we build by showing faster production, higher quality and enlarged freedom of design. In this paper, the potential and constraints of a specific digital slip-forming process, smart dynamic casting (SDC), are investigated with a material-focused approach in the complex task of producing thin folded structures. Firstly, the workability and the strength evolution of different material compositions are studied to achieve the constant processing rate for SDC. Secondly, friction between the formwork walls and the concrete, a key aspect in slip-casting, is studied with a simplified experimental setup to identify if any of these mixes would provide an advantage for processing. Finally, a theoretical framework is constructed to link the material properties, the process conditions and the designed geometry. This framework introduces the ‘SDC number’ as a simplified approach to formulate the process window, the suitable conditions for slip-forming. The experimental results prove the assumption of the model that friction is proportional to yield stress for all base compositions and acceleration methods regardless of the filling history. The results are evaluated in the context of the narrow process window of thin folded structures as well as the wider process window of columns. The necessity of consistent strength evolution is underlined for narrow windows. Further, friction is shown to be the highest initially, thus with both narrow and wide process windows, after a successful start-up the continuation of slipping is less prone to failure. The proposed theoretical model could provide material and geometry-specific slipping strategy for start time and slipping rate during production.

scholarly journals Mechanical properties of rotary swaged steel components

2021 ◽  
Author(s):  
Dhia Charni ◽  
Svetlana Ortmann-Ishkina ◽  
Marius Herrmann ◽  
Christian Schenck ◽  
Jérémy Epp
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Strain Curve ◽  
Dynamic Mechanical Properties ◽  
Process Conditions ◽  
Forming Process ◽  
Rotary Swaging ◽  
Surface Residual Stresses ◽  
Near Net Shape ◽  
As Stress

AbstractThe radial infeed rotary swaging is widely used as a diameter reduction forming process of axisymmetric workpieces, improving the mechanical properties with excellent near net shape forming. In the present study, rotary swaging experiments with different parameter setups were performed on steel tubes and bars under different material states and several resulting property modifications were investigated such as stress-strain curve, hardness, fatigue strength and surface residual stresses. The results show a significant work hardening induced by the rotary swaging process and an improvement in the static and dynamic mechanical properties was observed. Furthermore, the hardness distribution was homogenous in the cross section of the rotary swaged workpieces. Moreover, depending on the process conditions, different residual stresses distribution were generated along the surface.

Environmental footprint as a criterion in the ZTA composites forming process via centrifugal slip casting

2021 ◽  
Author(s):  
Justyna Zygmuntowicz ◽  
Justyna Tomaszewska ◽  
Radosław Żurowski ◽  
Marcin Wachowski ◽  
Ireneusz Szachogłuchowicz ◽  
...  
Keyword(s):  
Slip Casting ◽  
Environmental Footprint ◽  
Forming Process

Application of Tailored Heat Treated Blanks under Quasi Series Conditions

2007 ◽  
Vol 344 ◽  
pp. 383-390 ◽  
Author(s):  
Marion Merklein ◽  
Uwe Vogt
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Local Heat ◽  
Strength Distribution ◽  
Process Window ◽  
Short Term ◽  
Forming Process ◽  
Heat Treated ◽  
Set Up ◽  
The Impact

Tailored Heat Treated Blanks (THTB) are blanks that exhibit locally different strength specifically optimized for the succeeding forming process. The strength distribution is set by a local, short-term heat treatment modifying the mechanical properties of the material. Hence, THTB allow enhancing forming limits significantly leading to shorter and more robust manufacture process chains. In order to qualify the use of THTB under quasi series conditions, the interdependencies of the blank’s local heat treatment and the entire process chain of the car body manufacture have to be analyzed. In this respect, the impact of a short-term heat treatment on the mechanical properties of AA6181PX, a commonly used aluminum alloy in today’s car bodies, was studied. Also the influence of a short-term heat treatment on the coil lubricant, usually already applied by the material supplier, was given a closer look. Based on these experiments process restrictions for the application of THTB in an industrial automotive environment were derived and a process window for the THTB design was set up. In conclusion, strategies were defined how to enhance the found process boundaries leading to a more robust process window.

scholarly journals Rapid prototyping of a complex model for the manufacture of plaster molds for slip casting ceramic

Cerâmica ◽  
2014 ◽  
Vol 60 (356) ◽  
pp. 465-470 ◽  
Author(s):  
D. P. C. Velazco ◽  
E. F. Sancet ◽  
F. Urbaneja ◽  
M. Piccico ◽  
M. F. Serra ◽  
...  
Keyword(s):  
Rapid Prototyping ◽  
New Technologies ◽  
Slip Casting ◽  
Complex Model ◽  
Computer Assisted ◽  
Plaster Mold ◽  
Digital Format ◽  
Wide Range ◽  
3D Scanners ◽  
Ceramic Manufacturing

Computer assisted designing (CAD) is well known for several decades and employed for ceramic manufacturing almost since the beginning, but usually employed in the first part of the projectual ideation processes, neither in the prototyping nor in the manufacturing stages. The rapid prototyping machines, also known as 3D printers, have the capacity to produce in a few hours real pieces using plastic materials of high resistance, with great precision and similarity with respect to the original, based on unprecedented digital models produced by means of modeling with specific design software or from the digitalization of existing parts using the so-called 3D scanners. The main objective of the work is to develop the methodology used in the entire process of building a part in ceramics from the interrelationship between traditional techniques and new technologies for the manufacture of prototypes. And to take advantage of the benefits that allow us this new reproduction technology. The experience was based on the generation of a complex piece, in digital format, which served as the model. A regular 15 cm icosahedron presented features complex enough not to advise the production of the model by means of the traditional techniques of ceramics (manual or mechanical). From this digital model, a plaster mold was made in the traditional way in order to slip cast clay based slurries, freely dried in air and fired and glazed in the traditional way. This experience has shown the working hypothesis and opens up the possibility of new lines of work to academic and technological levels that will be explored in the near future. This technology provides a wide range of options to address the formal aspect of a part to be performed for the field of design, architecture, industrial design, the traditional pottery, ceramic art, etc., which allow you to amplify the formal possibilities, save time and therefore costs when drafting the necessary and appropriate matrixes to each requirement.

Flow Stress Experimental Determination for Warm-Forming Process

2011 ◽  
Author(s):  
Ting Fai Kong ◽  
Luen Chow Chan ◽  
Tai Chiu Lee
Keyword(s):  
Stainless Steel ◽  
Flow Stress ◽  
Room Temperature ◽  
Warm Forming ◽  
Recrystallization Temperature ◽  
Process Conditions ◽  
Compression Tests ◽  
Forming Process ◽  
Forming Temperature ◽  
Flow Stress Data

Warm forming is a manufacturing process in which a workpiece is formed into a desired shape at a temperature range between room temperature and material recrystallization temperature. Flow stress is expressed as a function of the strain, strain rate, and temperature. Based on such information, engineers can predict deformation behavior of material in the process. The majority of existing studies on flow stress mainly focus on the deformation and microstructure of alloys at temperature higher than their recrystallization temperatures or at room temperature. Not much works have been presented on flow stress at warm-forming temperatures. This study aimed to determine the flow stress of stainless steel AISI 316L and titanium TA2 using specially modified equipment. Comparing with the conventional method, the equipment developed for uniaxial compression tests has be verified to be an economical and feasible solution to accurately obtain flow stress data at warm-forming temperatures. With average strain rates of 0.01, 0.1, and 1 /s, the stainless steel was tested at degree 600, 650, 700, 750, and 800 °C and the titanium was tested at 500, 550, 600, 650, and 700 °C. Both materials softened at increasing temperatures. The overall flow stress of stainless steel was approximately 40 % more sensitive to the temperature compared to that of titanium. In order to increase the efficiency of forming process, it was suggested that the stainless steel should be formed at a higher warm-forming temperature, i.e. 800 °C. These findings are a practical reference that enables the industry to evaluate various process conditions in warm-forming without going through expensive and time consuming tests.

Fabrication of an All-Ceramic Implant by Slip Casting of Nanoscale Zirconia Powder

2020 ◽  
Vol 20 (9) ◽  
pp. 5703-5706
Author(s):  
Dae Sung Kim ◽  
Jong Kook Lee
Keyword(s):  
High Surface ◽  
Slip Casting ◽  
Tetragonal Zirconia ◽  
Solid Content ◽  
Solid Loading ◽  
Forming Process ◽  
Surface Cracking ◽  
All Ceramic ◽  
Mechanical Machining ◽  
Zirconia Implants

Dental implants are typically composed of 3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals). Most dental zirconia implants are currently fabricated via mechanical machining. However, during the machining of zirconia green bodies, many cracks form on the surface. To prevent surface crack formation on the implants, shape forming of the zirconia is necessary using methods such as slip casting. Herein, we fabricated green compacts using slip casting, candidate forming process to reduce surface cracking. To fabricate an optimal 3Y-TZP implant by slip casting and sintering, we prepared a suitable 3Y-TZP slurry for slip casting by adjusting the viscosity via pH, dispersant agent content, and solid loading refinement. Green compacts were prepared by the slip casting of all-ceramic zirconia implants fabricated using optimal slurry conditions, for example, 60 wt% solid content, 1 wt% dispersant, pH 12 and post-sintering at 1450 °C for 2 h. All sintered bodies contained a tetragonal phase with a high sintered density of approximately 6.07 g/cm3, good mechanical hardness of approximately 1367 Hv, grain size of 220 nm, and high surface roughness without cracks.

A Study on Using Cover Blank in Single Point Incremental Forming Process by Finite Element Analysis

2015 ◽  
Vol 809-810 ◽  
pp. 277-282
Author(s):  
Khalil Ibrahim Abass
Keyword(s):  
Tool Path ◽  
Incremental Forming ◽  
Sheet Material ◽  
Single Point ◽  
Complex Nature ◽  
Work Piece ◽  
Process Conditions ◽  
Single Point Incremental Forming ◽  
Forming Process ◽  
Highly Nonlinear

The Single Point Incremental Forming Process (SPIF) is a forming technique of sheet material based on layered manufacturing principles. The forming tool is moved along the tool path while the edges of sheet material are clamped. The finished part is manufactured by the CNC machine. SPIF involves extensive plastic deformation and the description of the process is more complicated by highly nonlinear boundary conditions, namely contact and frictional effects have been accomplished. However, due to the complex nature of these models, numerical approaches dominated by the FEA are now in widespread use. The paper presents the data and main results of a study on effect of using cover blank in SPIF through FEA. The considered SPIF has been studied under certain process conditions referring to the test work piece, tool, etc., applying ANSYS 11.0. The results show that the simulation model can predict an ideal profile of processing track, spring back error of SPIF, the behavior of contact tool-work piece, the product accuracy by evaluation its thickness and strain distributions, the contact status and chattering among surface interface tool-work piece.

An Elasto-Plastic Finite Element Analysis of the Hat-Type Drawing Process of Sheet Metal

2006 ◽  
Vol 505-507 ◽  
pp. 709-714
Author(s):  
Tsung Chia Chen ◽  
You Min Huang
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Moving Boundary ◽  
Contact Problems ◽  
Computer Code ◽  
Plastic State ◽  
Process Conditions ◽  
Drawing Process ◽  
Forming Process ◽  
Element Analysis

This study aims to clarify the process conditions of the hat-type drawing of a sheet metal of steel. It provides a model that predicts not only the correct punch load for drawing, but also the precise final shape of products after unloading, based on the tensile properties of the material and the geometry of the tools used. An elasto-plastic incremental finite-element computer code, based on an updated Lagrangian formulation, was developed to simulate the hat-type drawing of sheet metal. In particular, selective reduced integration was adopted to formulate the stiffness matrix. The extended r-minimum technique was used to deal with the elasto-plastic state and contact problems at the tool-metal interface. A series of simulations were performed to validate the formulation in the theory, leading to the development of the computer codes. The whole deformation history and the distribution of stress and strain during the forming process were obtained by carefully considering the moving boundary condition in the finite-element method. Results in this study clearly demonstrated that the computer code for simulating the hat-type drawing process was efficient.

Press-Shaving Characteristics of Ultrahigh-Strength Steel Sheets

2013 ◽  
Vol 554-557 ◽  
pp. 1879-1886 ◽  
Author(s):  
Masao Murakawa ◽  
Kenta Nakamura ◽  
Tomio Shionome ◽  
Fumitoshi Komuro ◽  
Giichirou Muro ◽  
...  
Keyword(s):  
Surface Quality ◽  
New Technologies ◽  
High Strength ◽  
Process Conditions ◽  
Steel Sheets ◽  
Ultrahigh Strength ◽  
Ultrahigh Strength Steel ◽  
Experimental Researches ◽  
Very High

The paper proposes new technologies able to improve the surface quality in the case of press-shaving applied to very high strength materials. Experimental researches were developed and the best combination of process conditions was identified.

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