Satisfying Piping Stress and Flexibility Requirements With the Implementation of Expansion Joints: Techno-Economical Optimization

There have been various attempts to deal with the optimization of solutions which involve expansion joints in piping systems where sufficient flexibility can’t be found using suitable pipe routing. The difficulty of piping designs which involve expansion joints is that they rely upon two engineering expertises: Pipe Flexibility and Stress Analysis on one side and Expansion Joint Design and Construction on the other. Arguably distinctively different, they have been looked upon as totally detached engineering disciplines and it is rarely that companies have two of these experts residing under the same roof. Pipe Stress Engineers basically relied on support form Expansion Joint Experts on “as required basis” and called upon their knowledge only when needed. Thus, we have the situation where knowledge related to the design and construction of expansion joints sits with expansion joints manufacturing companies, which are totally separate and often remote entities in the piping design process. Even so, the ever present demand for techno-economical optimizations, points us to the following observations. The “Traditional method”, where Pipe Stress Engineer defines on his own the requirements for expansion joints and describes them in the technical specification for purchasing is, or should be, a theme of the past. This approach may be used only as a first attempt in search for the solution, but given that it never heads in the direction of achieving optimal techno-economical results, needs to be upgraded with additional steps.

Computational Design Synthesis: A Model-Based Approach for Complex Systems

The design of systems architectures often involve a combinatorial design-space made of technological and architectural choices. A complete or large exploration of this design space requires the use of a method to generate and evaluate design alternatives. This paper proposes an innovative approach for the design-space exploration of systems architectures. The SAMOA (System Architecture Model-based OptimizAtion) tool associated to the method is also introduced. The method permits to create a large number of various system architectures combining a set of possible components to address given system functions. The method relies on models that are used to represent the problem and the solutions and to evaluate architecture performances. An algorithm first synthesizes design alternatives (a physical architecture associated to a functional allocation) based on the functional architecture of the system, the system interfaces, a library of available components and user-defined design rules. Chains of components are sequentially added to an initially empty architecture until all functions are fulfilled. The design rules permit to guarantee the viability and validity of the chains of components and, consequently, of the generated architectures. The design space exploration is then performed in a smart way through the use of an evolutionary algorithm, the evolution mechanisms of which are specific to system architecting. Evaluation modules permit to assess the performances of alternatives based on the structure of the architecture model and the data embedded in the component models. These performances are used to select the best generated architectures considering constraints and quality metrics. This selection is based on the Pareto-dominance-based NSGA-II algorithm or, alternatively, on an interactive preference-based algorithm. Iterating over this evolution-evaluation-selection process permits to increase the quality of solutions and, thus, to highlight the regions of interest of the design-space which can be used as a base for further manual investigations. By using this method, the system designers have a larger confidence in the optimality of the adopted architecture than using a classical derivative approach as many more solutions are evaluated. Also, the method permits to quickly evaluate the trade-offs between the different considered criteria. Finally, the method can also be used to evaluate the impact of a technology on the system performances not only by a substituting a technology by another but also by adapting the architecture of the system.

Walking Trajectory Optimization With Rotation of the Feet for a Planar Bipedal Robot With Four-Bar Knees

The design of a knee joint is a key issue in robotics and biomechanics to improve the compatibility between prosthesis and human movements and to improve the bipedal robot performances. We propose a novel design for the knee joint of a planar bipedal robot, based on a four-bar linkage. The dynamic model of the planar bipedal robot is calculated. We design walking reference trajectories with double support phases, single supports with a flat contact of the foot in the ground and single support phases with rotation of the foot around the toe. During the double support phase, both feet rotate. This phase is ended by an impact on the ground of the toe of one foot, the other foot taking off. The single support phase is ended by an impact of the swing foot heel, the other foot keeping contact with the ground through its toe. For both gaits, the reference trajectories of the rotational joints are prescribed by polynomial functions in time. A parametric optimization problem is presented for the determination of the parameters corresponding to the optimal cyclic walking gaits. The main contribution of this paper is the design of a dynamical stable walking gait with double support phases with feet rotation, impacts and single support phases for this novel bipedal robot.

Toward the Use of Pareto Performance Solutions and Pareto Robustness Solutions for Multi-Objective Robust Optimization Problems

For Multi-Objective Robust Optimization Problem (MOROP), it is important to obtain design solutions that are both optimal and robust. To find these solutions, usually, the designer need to set a threshold of the variation of Performance Functions (PFs) before optimization, or add the effects of uncertainties on the original PFs to generate a new Pareto robust front. In this paper, we divide a MOROP into two Multi-Objective Optimization Problems (MOOPs). One is the original MOOP, another one is that we take the Robustness Functions (RFs), robust counterparts of the original PFs, as optimization objectives. After solving these two MOOPs separately, two sets of solutions come out, namely the Pareto Performance Solutions (PP) and the Pareto Robustness Solutions (PR). Make a further development on these two sets, we can get two types of solutions, namely the Pareto Robustness Solutions among the Pareto Performance Solutions (PR(PP)), and the Pareto Performance Solutions among the Pareto Robustness Solutions (PP(PR)). Further more, the intersection of PR(PP) and PP(PR) can represent the intersection of PR and PP well. Then the designer can choose good solutions by comparing the results of PR(PP) and PP(PR). Thanks to this method, we can find out the optimal and robust solutions without setting the threshold of the variation of PFs nor losing the initial Pareto front. Finally, an illustrative example highlights the contributions of the paper.

Recycling of Carbon Fiber: Identification of Bases for a Synergy Between Recyclers and Designers

In order to decrease both energy consumption and CO2 emissions, the automotive, aeronautics and aerospace industries aim at making lighter vehicles. To achieve this, composite materials provide good opportunities, ensuring high material properties and free definition of geometry. As an example, for cold applications, the use of carbon fiber/thermoset composites is ever increasing, in spite of a high fiber price. But in a global and eco-friendly approach, the major limitation for their use remains their potential recyclability. Recycling a composite means having a recycling technology available, getting a dismantle solution and an access for the product, and disposing identification plus selection possibilities to the materials. Thus, carbon fibers recovery (i.e. recycling and re-processing) would both help design engineers to balance energy efficiency and cost, and open new opportunities for developing second-life composites, dedicated to the manufacture of medium or low loaded parts (non-structural in many cases). A first section presents an overview of composite recycling possibilities. Indeed, environmentally and economically, composite incineration is not attractive (even with an energetic valorization), let-alone burying. Reuse and recycling thus remain the two most interesting options. Aeronautics offers a high potential in terms of fiber deposit. In southwest France, composites recycling will increase in terms of quantity due to dismantling platforms Tarmac (dedicated to civil aircraft applications) and P2P (for the disassembly of ballistic weapons). In addition, from a technical point of view, and even if end-of-life solutions for composites still remain under development, solvolysis (i.e. water under supercritical conditions) already offers the opportunity to recover carbon fibers. The resulting recyclate retains up to 90 percent of the fiber’s mechanical properties. A second part will explore the recycling to design issue (i.e. how recycling processes have to balance the previous aspects of the end-of-life proposal). The recycler clearly becomes a new supplier in the carbon fiber lifecycle, by revalorizing wastes with alternatives to burning. Moreover, increasing carbon fiber shelf life reduces its product life impact. Finally, promoting carbon fiber end-of-life would ensure to link aeronautics, automotive, and leisure and sports industries; but one can create demand for recycled reinforcement, by packaging it in useful and attractive forms for those end-users (e.g. pseudo-continuous fiber, felt, strips, bands, patches, etc.). These sections will be enlightened by several examples from collaborations between I2M and local industries.

A Functional Approach to Optimal Dimensioning of Automotive Transmission Shafts

The paper deals with a functional approach to optimal dimensioning of automotive transmission shafts. In particular, the paper summarizes the results of a research activity developed on automotive transmission shafts to reduce the unpleasant movement of the transmission lever known as “shift lever movement”. The design problem was faced by focusing the axial clearances of the wheels assembled on the transmission shaft. First, the functional approach to optimal dimensioning proceeds from the study of different working conditions of the automotive manual transmission and focuses on corresponding geometrical constraints and design parameters. Then, it uses simplified schemes, each of them related to a different working condition, to set a series of functional dimensioning loops for the transmission shaft. Subsequently, the approach introduces an appropriate index to evaluate the Information Content for each dimensioning scheme and it addresses the optimal dimensioning scheme, related to the minimization of the Information Content. After this, the approach foresees worst-case to check the axial clearances of the wheels assembled on the shaft. In a such way the effect of the dimensioning are directly evaluated in terms of performances of the transmission. In fact, the reduction of axial clearances for the wheels assembled on the shaft causes a direct reduction of the “shift lever movement”. The functional approach to optimal dimensioning is applied to an automotive transmission set and the proposed dimensioning schema of the shaft is compared with different dimensioning schemes including one currently used in an international automotive company. A final discussion of the results, in terms of reduction of axial clearances of the parts assembled on the shaft, is provided.

Consideration of the Manufacturing Trajectories in a Global Design for Additive Manufacturing Methodology

Additive Manufacturing (AM) is a new way of part production which opens up new perspectives of conception as mass and cost reduction and increase of functionalities. However these processes have their own characteristics which as for all the manufacturing processes have a direct impact on the manufactured parts quality. Especially, because the manufacturing trajectories have a influence on the physical phenomena during the process, they have also a strong impact on the quality of the produced parts in terms of geometry. In this paper, the choice of manufacturing trajectories and their impacts on the final shape and quality of the parts is integrated into a global Design For Additive Manufacturing (DFAM) methodology which allows to move from functional specifications of a design problem to a proposition of an adapted part for AM processes.

3D Information Management Enabling Manufacture Engineering

Industrial companies are confronted to reverse engineering on mechanical components. They have to define a new process planning from 3D information (points cloud, drawings, etc.). The component has to be re-engineered in order to improve and optimize new manufacturing processes. According to surveys, reverse engineering approaches begin to be supported by Knowledge Base engineering Systems (KBS). These systems are efficient to quickly obtain CAD models based on functional features. These models are successful for redesigning activities and then for defining a process planning. Industrial companies often need to re-engineered components in order to define directly a new process planning. In this case CAD models, based on functional features, are not useful. This paper suggests an approach called Reverse Engineering For Manufacturing (REFM) which allows to directly obtain a CAPP (Computer Aided Process Planning) model from 3D information. The system management is based on Design For Manufacturing (DFM) approach and enables to manage manufacturing information (such as the number of fixtures, the kind of milling operations, etc.). In addition, this system management allows to define process planning alternatives. The aim of the paper is to show the concept of REFM approach according to a use case.

State of the Art in the Eco-Design Field: Toward Specifications for the Integration of Eco-Design in the Automotive Sector

This paper lies within the integration of an eco-design method adapted to the Innovation structure at a car manufacturer. The environmental constraints in the automotive industry are more and more important (European emission standards for exhaust emissions, European directive on end-of life vehicles …). Eco-design is a new manner to design products related to the concept of sustainable development, which combines economy and ecology and put the environmental criterion alongside the classical criterions of design. The goal of this study is to identify the specifications of a strategy for integrating the dimension “Environment”. This strategy is applied in the innovation process thanks to eco-design tools which are the learning vectors for an organization, and therefore support a learning process. This process is structured with the interactions between the management of firm, the environment department, and the design team. Therefore we first make a synthesis of the different classifications of eco-design tools and use two categories: diagnosis and improvement. Second, as our goal is the integration in the Innovation structure and within a design process, we analyze some design process models and highlight the RID (Research, Innovation structure, Development) concept. Third, the main practices of several car makers are synthetized and a focus on three of them (Volvo, Ford, and Volkswagen) is made; we link their strategies with the concept of RID. Finally in the fourth part, we propose a model of a strategy for integrating eco-design practices based on the three examples and supported by a learning process.