Unification of the a priori inconsistencies checking among assembly constraints in assembly sequence planning.

International audienceSequence planning generation is an important problem in assembly line design. A good assembly sequence can help to reduce the cost and time of the manufacturing process. This paper focuses on assembly sequence planning (ASP) known as a hard combinatorial optimization problem. Although the ASP problem has been tackled via even more sophisticated optimization techniques, these techniques are often inefficient for proposing feasible assembly sequences that satisfy the assembly planners' preferences. This paper presents an approach that makes easier to check the validity of operations in assembly process. It is based on a model of the assembly planners' preferences by means of strategic constraints. It helps to check a priori the consistency of the assembly constraints (strategic an operative constraints) given by the assembly system designers before and while running an assembly plan generation algorithm. This approach reduces the solution space significantly

Design and finite element analysis of interference press-fit aluminium nut

Construction of mechanical platforms requires a suitable method for assembling two physical components. One of the assembly methods that are being used for discrete hardware component is called fasteners. In the world of Technical Vocational Education Training (TVET), some projects require students to design and produce a product that will involve the installation of mechanical components. Taking into account the difficulties faced to make such assembly, joining process involved cutting the parts accurately until the components could be mated together. Thus, the fastener innovation was rather innovated to provide a more effective alternative method. The Interference Press-fit Aluminum Nut (INPREANUT) has designed and manufactured to meet such purpose. Quality Function Deployment (QFD) is used to translate the user needs and requirements into technical requirements. Once this step is completed, Design for Manufacturing and Assembly (DFMA) is used to select the best approach in assembly to reduce the constraints such as assembly time, efficiency and most importantly, cost. During the design process of INPREANUT, the strength of the connection between INPREANUT with aluminum round tube was analyzed using Finite Element Analysis (FEA). The CA TIA 3D software was employed to design INPREANUT being imported into ANSYS software to analyse the INPREANUT' s shear strength. The strength of a mechanical connectivity is a key requirement to ensure that it has the expected friction force as well able to meet some of the other features. The features are easy to install, safe, lightweight, saves time and accurate. After completing the preliminary design and analysis, the INPREANUT is then fabricated and experiments performed to verify that the numerical methods used correlates with real measurement values. It is hoped that the INPREANUT fabrication will able to help students to make mechanical assembly components quickly, accurately and economically

Extracting, managing, and exploiting the semantics of mechanical CAD models in assembly tasks

The manufacturing of mechanical products is increasingly assisted by technologies that exploit the CAD model of the final assembly to address complex tasks in an automated and simplified way, to reduce development time and costs. However, it is proven that industrial CAD models are heterogeneous objects, involving different design conventions, providing geometric data on parts but often lacking explicit semantic information on their functionalities. As a consequence, existing approaches are mainly mathematics-based or need expert intervention to interpret assembly components, and this is limiting. The work presented in the thesis is placed in this context and aims at automatically extracting and leveraging in industrial applications high-level semantic information from B-rep models of mechanical products in standard format (e.g. STEP). This makes possible the development of promising knowledge intensive processes that take into account the engineering meaning of the parts and their relationships. The guiding idea is to define a rule-based approach that matches the shape features, the dimensional relations, and the mounting schemes strictly governing real mechanical assemblies with the geometric and topological properties that can be retrieved in CAD models of assemblies. More in practice, a standalone system is implemented which carries out two distinct operations, namely the data extraction and the data exploitation. The first involves all the steps necessary to process and analyze the geometric objects representing the parts of the assembly to infer their engineering meaning. It returns an enriched product model representation based on a new data structure, denoted as liaison, containing all the extracted information. The new product model representation, then, stands at the basis of the data exploitation phase, where assembly tasks, such as subassembly identification, assembly planning, and design for assembly, are addressed in a more effective way

Adjustable Head Tube Angle Headset

This final design review report describes the design, manufacture, and test process of a bicycle headset capable of quickly and easily adjusting the effective head tube angle. The evolution of mountain bike geometry has forced bike designers to compromise between climbing and descending performance when choosing a head tube angle. A headset capable of quickly adjusting the effective head tube angle would allow riders to optimize their bike’s geometry for different stages of riding. This report details the research, idea generation, concept development and selection, design, manufacturing, and testing of our adjustable head tube angle headset

Vehicle Wheelchair Storage Final Design Report

Many people who use wheelchairs are very active. They have errands to run and lives to live just like everybody else. For a busy person who uses a wheelchair there are currently no quick methods for storing and unloading your wheelchair from your vehicle that do not require expensive custom modifications which can ruin the resell value and the aesthetics of the vehicle. This has resulted in users hastily loading their wheelchairs which can cause damage to the wheelchair, the vehicle, and other passengers while the vehicle is in motion. The goal of this project was to develop a wheelchair storage system that can be installed in any vehicle and securely store any wheelchair during transportation. The device allows for a wheelchair to be quickly and compactly stored behind the driver’s seat. Hopefully by making this process quick and safe this device can improve the lives of many users

Computer Aided Optimal Robotic Assembly Sequence Generation

Robots are widely used for assembly operations across manufacturing industries to attain high productivity through automation. An appropriate robotic assembly sequence further minimizes the total production lead time and overall cost by minimizing the number of assembly direction changes, assembly gripper changes and assembly energy thus selection of a valid optimal robotic assembly sequence is significantly essential to achieve economized manufacturing process. An optimal assembly sequence must comply with various assembly requirements in order to make sure that the sequence of assembly operations is functionally feasible in physical environment. In order to test an assembly sequence for its practical possibility, necessary assembly information must be collected accurately from the product. Obtaining such assembly information from product drawings or Computer Aided Design (CAD) models in manual mode were involved in lots of complexity and needs high level skills to ensure correctness. Though retrieving such information from products with less number of parts is simple and less time consuming, for products composed of huge number parts it is very complicated and time consuming. Besides retrieving the assembly information, using it for validating an assembly sequence further raises the complexity of the Assembly Sequence Generation (ASG) problem. To perform optimal feasible assembly sequence generation efficiently, an effective computer aided automated method is developed and executed at two phases. The first phase of research is mainly focused on representing the assembly information in a streamlined manner by considering all possible states of assembly configurations for ease of computerization and developing efficient methods to extract the assembly information automatically from CAD environment though Computer Aided Automation (CAA). These methods basically use assembly contact analysis, part transformations and laws of equilibrium & balancing of rigid bodies. From the existing ASG methods, it is observed most of the researchers ignored/not-considered few of the assembly information such as assembly stability data and mechanical feasibility data due to higher complexity in retrieving it from CAD environment....

Bone Remodeling Monitor

The impact of bone loss due to different mechanical loadings in microgravity is a major concern for astronauts upon reintroduction to gravitational forces in exploration missions to the Moon and Mars. it has been shown that astronauts not only lose bone at differing rates, with levels up to 2% per month, but each astronaut will respond to bone loss treatments differently. Pre- and post-flight imaging techniques and frozen urine samples for post-flight laboratory immunoassays To develop a novel, non-invasive, highly . sensitive, portable, intuitive, and low-powered device to measure bone resorption levels in 'real time' to provide rapid and Individualized feedback to maximize the efficacy of bone loss countermeasures 1. Collect urine specimen and analyze the level of bone resorption marker, DPD (deoxypridinoline) excreted. 2. Antibodies specific to DPD conjugated with nanoshells and mixed with specimen, the change in absorbance from agglutination is measured by an optical device. 3. The concentration of DPD is displayed and recorded on a PD

Disassembly sequence planning validated thru augmented reality for a speed reducer

The lifecycle of a product is getting shorter in today’s market realities. Latest developments in the industry are heading towards achieving products that are easy to recycle, by developing further technological advances in raw materials ought to include input from End of Life (EOL) products so a reduction of natural harm could be achieved, hence reducing the overall production environmental footprint. Therefore, the approach taken as a design for environment, a key request nowadays in order to develop products that would ease the reverse manufacturing process leading to a more efficient element recycling for later use as spare parts or remanufacturing. The methodology proposed compares three probable disassembly sequences following a comparison of literature-found procedures between genetic algorithms and as a “state space search” problem, followed by a hybrid approach developed by the authors. Time and evaluation of these procedures reached to the best performing sequence. A subsequent augmented reality disassembly simulation was performed with the top-scored operation sequence with which the user is better able to familiarize himself with the assembly than a traditional paper manual, therefore enlightening the feasibility of the top performing sequence in the real world

A study to analyze and improve mechanical and electro-mechanical designs using design for quality manufacturability (DFQM) technique

The competitive nature of modern manufacturing demands that an innovative approach be used to build advanced and robust designs. Shortening the product development time, which is the period from initial design to full production, is a priority to most manufacturers today. Design for Quality Manufacturability (DFQM) is a methodology to address manufacturing / assembly quality issues during product design. As a consequence DFQM helps shorten the product development time. The DFQM methodology addresses the issue of quality manufacturability (QM) - the likely hood that defects will occur during the manufacture of a product in a standard plant. The DFQM architecture identifies a variety of design factors and variables that influence specific defects. The error catalysts are described in the form of catalysis graphs. Each catalysis graph leads to a value between 0 and 1 , based on the factor variables for the given design, implying the likelihood of occurrence of the specific defect. The overall QM index of design is derived from these values. In this thesis we introduce new error catalysts for the DFQM method. Further, we conducted case studies of a variety of designs and we present a couple of them in this thesis

ARES Cleaning System

In this Final Design Review, the team outlines the general scope of the ARES Cleaning System project and the final design direction chosen and built. This team consists of a group of four mechanical engineering students who have been tasked with designing and manufacturing an autonomous ARES cleaning system to help their sponsor, Fracsun, better track soiling losses measured at large solar arrays. They designed, conceptualized, manufactured, and tested throughout the project as they looked to create a final, functioning product. In creating this Final Design Review, they have identified how the product will perform the desired functions and what materials and manufacturing methods need to be used for further development. The team has chosen a specific design, while creating a functional prototype that can be improved in the future or used immediately with Fracsun. The team has also identified future recommendations so that it can be implemented into a wider range of environments and be mass produced. While most of the specifications laid out by the team were met, they have reflected on the project and determined what worked during the year long project and what can be improved in the future