Modeling In-Plane Deviations of Shapes to Come Based on Prior Deviation Features in Additive Manufacturing

2019 ◽  
pp. 339-350
Author(s):  
Arman Sabbaghi
Keyword(s):  
Additive Manufacturing ◽  
To Come

scholarly journals Novel cellular materials for energy absorption applications

2020 ◽  
Author(s):  
Mohammed Mudassir ◽  
Mahmoud Mansour
Keyword(s):  
Additive Manufacturing ◽  
Energy Absorption ◽  
Metal Foams ◽  
Cellular Materials ◽  
Cellular Structures ◽  
Senior Project ◽  
Key Factor ◽  
Good Energy ◽  
To Come ◽  
Energy Absorbing

Cellular materials such as metal foams are porous, lightweight structures that exhibit good energy absorption properties. They have been used for many years in various applications including energy absorption. Traditional cellular structures do not have consistent pore sizes and their behaviors and properties such as failure mechanisms and energy absorption are not always same even within the same batch. This is a major obstacle for their applications in critical areas where consistency is required. With the popularity of additive manufacturing, new interest has garnered around fabricating metal foams using this technology. It is necessary to study the possibility of designing cellular structures with additive manufacturing and their energy absorbing behavior before any sort of commercialization for critical applications is contemplated. The primary hypothesis of this senior project is to prove that energy absorbing cellular materials can be designed. Designing in this context is much like how a car can be designed to carry a certain number of passengers. To prove this hypothesis, the paper shows that the geometry is a key factor that affects energy absorption and that is possible to design the geometry in order to obtain certain behaviors and properties as desired. Much like designing a car, it requires technical expertise, ingenuity, experience and learning curve for designing cellular structures. It is simple to come with a design, but not so much when the design in constrained by stringent requirements for energy absorption and failure behaviors. The scope was limited to the study of metal foams such as the ones made from aluminum and titanium. The primary interest has been academic rather than finding ways to commercialize it. The study has been carried out using simulation and experimental verification has been suggested for future work. Nevertheless, the numerical or simulation results show that energy absorbing cellular structures can be designed that exhibit good energy absorption comparable to traditional metal foams but perhaps with better consistency and failure behaviors. The specific energy absorption was found to be 18 kJ/kg for aluminum metal foams and 23 kJ/kg for titanium metal foams. The average crushing force has been observed to be around 70 kN for aluminum and around 190 kN for titanium. These values are within the acceptable range for most traditional metal foams under similar conditions as simulated in this paper.

Escaping Tree-Support (ET-Sup): minimizing contact points for tree-like support structures in additive manufacturing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tsz-Ho Kwok
Keyword(s):  
Additive Manufacturing ◽  
Lead Time ◽  
Computation Time ◽  
Support Structures ◽  
Content Type ◽  
Contact Points ◽  
Clear Point ◽  
New Type ◽  
To Come ◽  
First Time

Purpose Support structures are often needed in additive manufacturing (AM) to print overhangs. However, they are the extra materials that must be removed afterwards. When the supports have many contacts to the model or are even enclosed inside some concavities, removing them is very challenging and has a risk of damaging the part. Therefore, the purpose of this paper is to develop a new type of tree-support, named Escaping Tree-Support (ET-Sup), which tries to build all the supports onto the build plate to minimize the number of contact points. Design/methodology/approach The methodology is to first classify the support points into three categories: clear, obstructed and enclosed. A clear point has nothing between it and the build plate; an obstructed point is not clear, but there exists a path for it to reach the build plate; and an enclosed point has no way to reach the build plate. With this classification, the path for the obstructed points to come clear can be found through linking them to the clear points. All the operations are performed efficiently with the help of a ray representation. Findings The method is tested on different overhang features, including a lattice ball and a mushroom shape with a concave cap. All the supports generated for the examples can find their way to the build plate, which looks like they are escaping from the model. The computation time is around one second for these cases. Originality/value This is the first time truly realizing this “escaping” property in the generation of tree-like support structures. With this ET-Sup, it is expected that the AM industries can reduce the manufacturing lead time and save much labor work in post-processing.

Zerspanung mit Industrierobotern/Robot machining – Hybrid manufacturing with industrial robots in tool and die constructions

2018 ◽  
Vol 108 (06) ◽  
pp. 429-434
Author(s):  
E. Abele ◽  
C. Baier ◽  
C. Tepper
Keyword(s):  
Additive Manufacturing ◽  
Chip Thickness ◽  
Industrial Robots ◽  
Hybrid Manufacturing ◽  
Machining Accuracy ◽  
Starting Point ◽  
Robot Machining ◽  
Good Starting Point ◽  
Near Net Shape ◽  
To Come

Additives Auftragschweißen bietet eine sehr gute Ausgangssituation für die Zerspanung mit Industrierobotern. Durch die additive, endkonturnahe Fertigung wird das Zerspanungsvolumen reduziert. So können Spandicken verringert und die Zerspanungskräfte verkleinert werden. Die Kombination der beiden robotergestützten Technologien zu einer hybriden Fertigung ermöglicht eine signifikante Steigerung der Oberflächengüte sowie der Bearbeitungsgenauigkeit nahe der Wiederholgenauigkeit von Industrierobotern.   Additive manufacturing offers a good starting point for machining with industrial robots. Additive, near-net-shape manufacturing allows decreasing chip thickness, which leads to a reduction of cutting forces. The combination of the two robot-based technologies for hybrid manufacturing thus enables a significant improvement of surface quality and increases machining accuracy to come close to the repeatability accuracy of industrial robots.

scholarly journals Novel Cellular Materials for Energy Absorption Applications

2020 ◽  
Author(s):  
Mohammed Mudassir ◽  
Mahmoud Mansour
Keyword(s):  
Additive Manufacturing ◽  
Energy Absorption ◽  
Metal Foams ◽  
Cellular Materials ◽  
Cellular Structures ◽  
Senior Project ◽  
Key Factor ◽  
Good Energy ◽  
To Come ◽  
Energy Absorbing

Cellular materials such as metal foams are porous, lightweight structures that exhibit good energy absorption properties. They have been used for many years in various applications including energy absorption. Traditional cellular structures do not have consistent pore sizes and their behaviors and properties such as failure mechanisms and energy absorption are not always same even within the same batch. This is a major obstacle for their applications in critical areas where consistency is required. With the popularity of additive manufacturing, new interest has garnered around fabricating metal foams using this technology. It is necessary to study the possibility of designing cellular structures with additive manufacturing and their energy absorbing behavior before any sort of commercialization for critical applications is contemplated. The primary hypothesis of this senior project is to prove that energy absorbing cellular materials can be designed. Designing in this context is much like how a car can be designed to carry a certain number of passengers. To prove this hypothesis, the paper shows that the geometry is a key factor that affects energy absorption and that is possible to design the geometry in order to obtain certain behaviors and properties as desired. Much like designing a car, it requires technical expertise, ingenuity, experience and learning curve for designing cellular structures. It is simple to come with a design, but not so much when the design in constrained by stringent requirements for energy absorption and failure behaviors. The scope was limited to the study of metal foams such as the ones made from aluminum and titanium. The primary interest has been academic rather than finding ways to commercialize it. The study has been carried out using simulation and experimental verification has been suggested for future work. Nevertheless, the numerical or simulation results show that energy absorbing cellular structures can be designed that exhibit good energy absorption comparable to traditional metal foams but perhaps with better consistency and failure behaviors. The specific energy absorption was found to be 18 kJ/kg for aluminum metal foams and 23 kJ/kg for titanium metal foams. The average crushing force has been observed to be around 70 kN for aluminum and around 190 kN for titanium. These values are within the acceptable range for most traditional metal foams under similar conditions as simulated in this paper.

Design for Manufacturability in Additive Manufacturing Using a Graph Based Approach

2015 ◽  
Author(s):  
Rajit Ranjan ◽  
Rutuja Samant ◽  
Sam Anand
Keyword(s):  
Additive Manufacturing ◽  
Relevant Literature ◽  
Design Guidelines ◽  
Layer By Layer ◽  
Design Rules ◽  
Novel Approach ◽  
To Come ◽  
The Relationship ◽  
Am Processes ◽  
Complex Parts

Additive Manufacturing (AM) processes are used to fabricate complex parts using a layer by layer approach. This enables designers to be more creative with their designs and build parts which may be difficult to manufacture using conventional processes. However, as AM is in its infancy, relevant literature with respect to design guidelines for AM is not readily available. This research proposes a novel approach to implement design guidelines in AM using a systematic graph based approach. These design rules will assist designers to come up with efficient part designs that can be manufactured with minimum part errors. The design rules are formulated by studying the relationship between input part geometry and AM process parameters. A feature graph based design analysis method is proposed along with a Producibility Index (PI) which is used to compare the designs. Modifications in part design based on these rules and their comparison is presented in the form of three case studies.

scholarly journals A Systematic Approach for Evaluating the Adoption of Additive Manufacturing in the Product Design Process

2021 ◽  
Vol 11 (3) ◽  
pp. 1210
Author(s):  
Roberto Raffaeli ◽  
Jacopo Lettori ◽  
Juliana Schmidt ◽  
Margherita Peruzzini ◽  
Marcello Pellicciari
Keyword(s):  
Additive Manufacturing ◽  
Systematic Approach ◽  
Complex Products ◽  
Everyday Work ◽  
Need To Evaluate ◽  
Product Design Process ◽  
To Come ◽  
Radical Solution ◽  
Algorithmic Procedure

Additive Manufacturing (AM) technologies have expanded the possibility of producing unconventional geometries, also increasing the freedom of design. However, in the designer’s everyday work, the decision regarding the adoption of AM for the production of a component is not straightforward. In fact, it is necessary to process much information regarding multiple fields to exploit the maximum potential of additive production. For example, there is a need to evaluate the properties of the printable materials, their compatibility with the specific application, redesign shapes accordingly to AM limits, and conceive unique and complex products. Additionally, procurement and logistics evaluations, as well as overall costs possibly extending to the entire life cycle, are necessary to come to a decision for a new and radical solution. In this context, this paper investigates the complex set of information involved in this process. Indeed, it proposes a framework to support and guide a designer by means of a structured and algorithmic procedure to evaluate the opportunity for the adoption of AM and come to an optimal design. A case study related to an ultralight aircraft part is reported to demonstrate the proposed decision process.

Investor-State Dispute Settlement under NAFTA Chapter 11: The Shape of Things to Come?

1998 ◽  
Vol 35 ◽  
pp. 263-290
Author(s):  
J. Anthony VanDuzer
Keyword(s):  
Free Trade Agreement ◽  
Dispute Settlement ◽  
Trade Agreement ◽  
Minimum Standards ◽  
The North ◽  
State Behaviour ◽  
Nafta Chapter 11 ◽  
To Come ◽  
The Right

SummaryRecently, there has been a proliferation of international agreements imposing minimum standards on states in respect of their treatment of foreign investors and allowing investors to initiate dispute settlement proceedings where a state violates these standards. Of greatest significance to Canada is Chapter 11 of the North American Free Trade Agreement, which provides both standards for state behaviour and the right to initiate binding arbitration. Since 1996, four cases have been brought under Chapter 11. This note describes the Chapter 11 process and suggests some of the issues that may arise as it is increasingly resorted to by investors.

Scanning Electron Microscopy-cuticular Lesions on the Roundworm Ascaris Suum

1970 ◽  
Vol 28 ◽  
pp. 114-115
Author(s):  
P. A. Madden ◽  
W. R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Freeze Drying ◽  
Room Temperature ◽  
Secondary Electron ◽  
Distilled Water ◽  
Freeze Dried ◽  
Silver Paint ◽  
To Come ◽  
Scanning Electron

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.

The microstructure change of low-carbon electrical steels by residual aluminum

1989 ◽  
Vol 47 ◽  
pp. 286-287
Author(s):  
C.K. Hou ◽  
C.T. Hu ◽  
Sanboh Lee
Keyword(s):  
Annealing Treatment ◽  
Low Carbon ◽  
Electrical Steels ◽  
Vacuum Degassing ◽  
Spherical Inclusions ◽  
Residual Aluminum ◽  
Average Grain Size ◽  
The Matrix ◽  
Fine Size ◽  
To Come

The fully processed low-carbon electrical steels are generally fabricated through vacuum degassing to reduce the carbon level and to avoid the need for any further decarburization annealing treatment. This investigation was conducted on eighteen heats of such steels with aluminum content ranging from 0.001% to 0.011% which was believed to come from the addition of ferroalloys.The sizes of all the observed grains are less than 24 μm, and gradually decrease as the content of aluminum is increased from 0.001% to 0.007%. For steels with residual aluminum greater than 0. 007%, the average grain size becomes constant and is about 8.8 μm as shown in Fig. 1. When the aluminum is increased, the observed grains are changed from the uniformly coarse and equiaxial shape to the fine size in the region near surfaces and the elongated shape in the central region. SEM and EDAX analysis of large spherical inclusions in the matrix indicate that silicate is the majority compound when the aluminum propotion is less than 0.003%, then the content of aluminum in compound inclusion increases with that in steel.

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