Design of Four-Bar-Mechanism Stability Using Over-Constraint

2016 ◽  
Author(s):  
Ahmad Alqasimi ◽  
Craig Lusk
Keyword(s):  
Potential Energy ◽  
Computer Aided Design ◽  
Main Idea ◽  
Spring Stiffness ◽  
Stable States ◽  
Stable Position ◽  
Design Considerations ◽  
Computer Aided ◽  
Aided Design ◽  
Energy Element

This paper presents a new concept and method to design mechanisms’ stability using over-constraint. The designs involve the use of parametric Computer-Aided Design (CAD) software to synthesize a mechanism’s geometry in order to achieve a design’s specific bistability requirements. This method ensures a stable position without the need of a hard-stop. There are two main initial design considerations that need to be met in this analysis. First, both (first and second) state of the mechanism should be chosen and should represent the mechanism’s desired stable positions. The first state is the position that the mechanism was manufactured or assembled at, whereas the second state is the position at which the mechanism is toggled to. The second consideration is the assumption that the magnitude of the joints’ torsional spring stiffness is small i.e. living hinges. The main idea is to attach a Potential Energy Element (PEE), such as a spring or a compliant link, to the four-bar mechanism such that it is unstretched in both stable positions and has to deform (stretch or compress) during the motion between stable states. This approach seems to allow the designer considerable freedom in amount of motion between stable states and in the amount of force required to toggle between stable states.

scholarly journals Computer Numerically Controlled Drawing Robot Based on Computer-Aided Design

2021 ◽  
Author(s):  
Antor Mahamudul Hashan ◽  
Abdullah Haidari ◽  
Srishti Saha ◽  
Titas Paul
Keyword(s):  
Open Source ◽  
Computer Aided Design ◽  
Low Cost ◽  
Rapid Development ◽  
Main Idea ◽  
Numerical Control ◽  
Computer Aided ◽  
Complex Circuits ◽  
Open Source Hardware ◽  
Aided Design

Due to the rapid development of technology, the use of numerically controlled machines in the industry is increasing. The main idea behind this paper is computer-aided design (CAD) based low-cost computer numerical control 2D drawing robot that can accurately draw complex circuits, diagrams, logos, etc. The system is created using open-source hardware and software, which makes it available at a low cost. The open-source LibreCAD application has been used for computer-aided design. Geometric data of a CAD model is converted to coordinate points using the python-based F-Engrave application. This system uses the Arduino UNO board as a signal generator of the universal g-code sender without compromising the performance. The proposed drawing robot is designed as a low-cost robot for educational purposes and aims to increase the student's interest in robotics and computer-aided design (CAD) skills to the next level. The drawing robot structure has been developed, and it meets the requirements of low cost with satisfactory experimental results.

scholarly journals Evolution of design considerations in complex craniofacial reconstruction using patient-specific implants

2016 ◽  
Vol 231 (6) ◽  
pp. 509-524 ◽  
Author(s):  
Sean Peel ◽  
Satyajeet Bhatia ◽  
Dominic Eggbeer ◽  
Daniel S Morris ◽  
Caroline Hayhurst
Keyword(s):  
Additive Manufacturing ◽  
Case Studies ◽  
Computer Aided Design ◽  
Titanium Implants ◽  
Patient Specific ◽  
Patient Case ◽  
Computer Aided Manufacturing ◽  
Design Considerations ◽  
Computer Aided ◽  
Aided Design

Previously published evidence has established major clinical benefits from using computer-aided design, computer-aided manufacturing, and additive manufacturing to produce patient-specific devices. These include cutting guides, drilling guides, positioning guides, and implants. However, custom devices produced using these methods are still not in routine use, particularly by the UK National Health Service. Oft-cited reasons for this slow uptake include the following: a higher up-front cost than conventionally fabricated devices, material-choice uncertainty, and a lack of long-term follow-up due to their relatively recent introduction. This article identifies a further gap in current knowledge – that of design rules, or key specification considerations for complex computer-aided design/computer-aided manufacturing/additive manufacturing devices. This research begins to address the gap by combining a detailed review of the literature with first-hand experience of interdisciplinary collaboration on five craniofacial patient case studies. In each patient case, bony lesions in the orbito-temporal region were segmented, excised, and reconstructed in the virtual environment. Three cases translated these digital plans into theatre via polymer surgical guides. Four cases utilised additive manufacturing to fabricate titanium implants. One implant was machined from polyether ether ketone. From the literature, articles with relevant abstracts were analysed to extract design considerations. In all, 19 frequently recurring design considerations were extracted from previous publications. Nine new design considerations were extracted from the case studies – on the basis of subjective clinical evaluation. These were synthesised to produce a design considerations framework to assist clinicians with prescribing and design engineers with modelling. Promising avenues for further research are proposed.

Computer Aided Design of Belt Conveyors for the Process and Manufacturing Industries

2005 ◽  
Author(s):  
Shahid Khalil ◽  
Tariq Masood ◽  
Ajaz Bashir Janjua
Keyword(s):  
Computer Aided Design ◽  
Material Handling ◽  
Parametric Design ◽  
Market Competition ◽  
Main Idea ◽  
Conventional Design ◽  
General Arrangement ◽  
Computer Aided ◽  
Belt Conveyors ◽  
Aided Design

Designing and manufacturing work on Material Handling Equipments specially material conveying system is being carried out in many heavy engineering companies. To overcome the time delay, in conventional design approach, for the design of belt conveyors by utilizing the CAD facilities is not only the need of time but is also necessary for the market competition in this area. This paper explains the methodology of converting the conventional design process of belt conveyors to Computer Aided Design (CAD). This includes software engineering approach and the usage of different tools in order to get a computer based solution for the design of belt conveyors. Application of parametric design and design for manufacturing concepts could also be followed. The main idea is to automate the drafting process and the lengthy calculations involved in the design phase. General arrangement or assembly of a belt conveyor is shown in Fig. 1.

Prototyping of Polymer based Microbioreactors: Micromachining by using Poly(Methyl Methacrylate) and Poly(Dimethylsiloxane) Polymer Materials

2013 ◽  
Vol 63 (1) ◽  
Author(s):  
Hazwan Halimoon ◽  
Muhd Nazrul Hisham Zainal Alam
Keyword(s):  
Methyl Methacrylate ◽  
High Precision ◽  
Computer Aided Design ◽  
Soft Lithography ◽  
Processing Time ◽  
Polymer Materials ◽  
Poly Methyl Methacrylate ◽  
Design Considerations ◽  
Computer Aided ◽  
Aided Design

Polymers have been widely accepted as materials for the fabrication of microbioreactor prototypes. In this work, microfabrication strategies namely the micromachining and casting (soft lithography) with the use poly(methyl methacrylate) (PMMA) and poly(dimethylsiloxane) (PDMS) polymers as substrates for fabrications were discussed in details. A step-by-step illustration (including examples on digital prototyping of the microbioreactor by using a computer-aided-design (CAD) software) for the above mentioned micromachining procedures, and discussions on the necessary design considerations were presented as well. In the work, we showed the simplicity of such machining procedures for the fabrication of microbioreactor prototypes. It was confirmed that through micromachining, microbioreactor prototypes can be fabricated by using poly(methyl methacrylate) (PMMA) and poly(dimethylsiloxane) (PDMS) polymers with high precision (down to one tenth of mm). It was also demonstrated that the processing time for the fabrication of the microbioreactor prototypes was in the order of few hours and maybe days for a complex reactor design. 

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