Method of Assessment of Casting Accuracy and Minimization of Machining Allowances

The publication demonstrates an accuracy assessment method for machine tool body casting utilizing an optical scanner and a reference design of the machine tool body. The process allows assessing the casting shape accuracy, as well as determining whether the size of the allowances of all work surfaces is sufficient for appropriate machining, corresponding to the construction design. The described method allows dispensing with the arduous manual operation - marking out. Marking out, depending on the size and complexity, might take several working shifts for prototype casting. In case of large and elaborate casts, as those of machine tool bodies, marking out is often restricted only to the first cast of the desired body produced in a given casting mold. Such course of action is based on an assumption that casting is reproducible; hence, no need to assess each and every individual cast. While this approach saves time, it often results in late detection of casting errors (allowance shifts or insufficiencies) during the actual machining process. That, in turn, results in considerable losses due to the disruption of the work process and often demands cast repair. The aim of the hereby presented study is to introduce a new technological premise dispensing with manual marking out as well as allowing fast verification of the cast shapes.

MarkUs: An Open-Source Web Application to Annotate Student Papers On-Line

A critical component of the learning process lies in the feedback that students receive on their work that validates their progress, identifies flaws in their thinking, and identifies skills that still need to be learned. Many higher-education institutions have developed an active pedagogy that gives students opportunities for different forms of assessment and feedback. This means that students have numerous lab exercises, assignments, and projects. Both instructors and students thus require effective tools to efficiently manage the submission, assessment, and individualized feedback of students’ work. The open-source web application MarkUs aims at meeting these needs: it facilitates the submission and assessment of students’ work. Students directly submit their work using MarkUs, rather than printing it, or sending it by email. The instructors or teaching assistants use MarkUs’s interface to view the students’ work, annotate it, and fill in a marking rubric. Students use the same interface to read the annotations and learn from the assessment. Managing the students’ submissions and the instructors assessments within a single online system, has led to several positive pedagogical outcomes: the number of late submissions has decreased, the assessment time has been drastically reduced, students can access their results and read the instructor’s feedback immediately after the grading process is completed. Using MarkUs has also significantly reduced the time that instructors spend collecting assignments, creating the marking schemes, passing them on to graders, handling special cases, and returning work to the students. In this paper, we introduce MarkUs’ features, and illustrate their benefits for higher education through our own teaching experiences and that of our colleagues. We also describe an important benefit of the fact that the tool itself is open-source. MarkUs has been developed entirely by students giving them a valuable learning opportunity as they work on a large software system that real users depend on. Virtuous circles indeed arise, with former users of MarkUs becoming developers and then supervisors of further development. We will conclude by drawing perspectives about forthcoming features and use, both technically and pedagogically.

Adaptable Fixturing Heads for Swarm Fixtures: Discussion of Two Designs

Driven by the trend of life-cycle design and sustainable production, an innovative project called self-reconfigurable intelligent swarm fixtures (SwarmItFIX) funded by the European Commission is being developed. The project investigates the application of robotic multi agent fixtures for the support of automotive and airplane body panels during their manufacturing and assembly processes. This paper addresses the exploration and development of the adaptable heads, which are the end-effector of the intelligent fixture. The head is able to adapt to the shape of the workpiece and freeze its shape after adaptation to provide stable support. Two kinds of head designs are discussed. The first design uses the pseudo-phase-change properties of a volume of bulk grains (metal sand) which can be clustered using a hydrostatic pressure to conform to a given workpiece shape. The second design investigated uses phase-change magneto-rheological (MR) fluid in a network of channels to allow and block the motion of a crown of miniature pistons. The initial experiments are carried out and their results show the effectiveness of the design.

Energy-Consistent Finite Element Modelling of Ferromagnetic Hysteresis

In this article we propose a macroscopic model for ferromagnetic hysteresis that is well-suited for finite element implementation. The model is readily vectorial and relies on a consistent thermodynamic formulation. In particular, the stored magnetic energy and the dissipated energy are known at all times, and not solely after the completion of closed hysteresis loops as is usually the case. The obtained incremental formulation is variationally consistent, i.e., all internal variables follow from the minimization of a thermodynamic potential. This variational approach is directly inspired from the kinematic hardening theory of plasticity, which opens the door for novel energy-consistent coupled mechanical/electromagnetic models.

New Interpretation of the Electrical Resistivity Measurements for Obtaining NiTi SMA Stress-Free Transformation Temperatures

The objective of this study is to clarify and to improve the interpretation of the ER measurements used to obtain NiTi SMA stress-free transformation temperatures for the austenite to martensite transformation process. To achieve this objective, the transformation temperatures of NiTi SMA wires are measured by ER using the Ling and Kaplow interpretation and are compared and complemented by weight fraction diagrams. The weight fractions are obtained from XRD profiles using the Parametric Rietveld refinement and adequate software. As a result of comparing both techniques, a new interpretation of the ER curves is proposed. This new interpretation is based on the shape of NiTi ER curve, which depends on the quantity of R-phase in the NiTi SMA. The quantity of the R-phase is obtained by weight fraction diagrams. According to the findings presented here, a new criterion for R-phase and martensite transformation temperatures is proposed.

Usability Testing of Ultra High-Strength Steels

New ultra high strength (UHS) steels have been developed in order to get advantages in machine design and construction. Following benefits can be obtained for example: - less material usage due to lighter constructions; - better payload and less fuel consumption in vehicle industry; - energy saving in material production. A rough distinction of structural steels can be defined to ductile steels, with tensile strength less than 300 MPa, and high strength steels, up to 700 Mpa. A steel material can be defined as UHS steel when the tensile strength exceeds 700 MPa. Steels with yield strength of 1500 Mpa have been developed so far. UHS steels can also be divided into structural steels and wear resistant steels. With the tensile strength also the hardness increases and the tensile strain decreases. That causes several difficulties when the material is processed into products. Especially mechanical processing like bending, machining and shearing gets difficult as the material strength increases. That causes problems for the construction material users to find the proper manufacturing methods in production. In Oulu University Production Technology Laboratory material processing tests have been performed during several years in co-operation with the local steel manufacturer. The usability tests comprise mainly of bending and machining tests. Shearing and welding tests have been made to a smaller extent. Also laser treatment has been used for local heat conditioning in order to improve the bending and shearing properties, but these techniques are not yet widely used in production. The bending tests are carried out with standard bending tools and test steel plates with standard dimensions. The plate thickness varies depending on the test material. The target is to determine the reliable minimum bending radiuses whereby the plate can be bent without failure, from both sides and along the rolling direction and orthogonally to that. Also the springback angle is measured and the bent surfaces are evaluated according to several criteria. When necessary, also the mechanical testing of the formed material is carried out. The machining tests are made mainly by drilling. Also some milling tests have been performed. Drilling is a convenient way of machining testing because a substantial amount of holes can be drilled in one test plate. The drilling power can be observed precisely by monitoring the spindle power. Also a variety of different tool types can be used, from uncoated HSS drills to boring tools with indexable inserts. The optimal machining parameters (feed and speed) will be defined according to maximum tool life and minimum machining costs.

New Development in High Efficiency Deep Grinding

High Efficiency Deep Grinding (HEDG) has been known to secure high removal rates in grinding processes at high wheel speed, relatively large depth of cut and moderately high work speed. High removal rates in HEDG are associated with very efficient grinding and secure very low specific energy comparable to conventional cutting processes. Though there exist HEDG-enabled machine tools, the wide spread of HEDG has been very limited due to the requirement for the machine tool and process design to ensure workpiece surface integrity. HEDG is an aggressive machining process that requires an adequate selection of grinding parameters in order to be successful within a given machine tool and workpiece configuration. This paper presents progress made in the development of a specialised HEDG machine. Results of HEDG processes obtained from the designed machine tool are presented to illustrate achievable high specific removal rates. Specific grinding energies are shown alongside with measured contact arc temperatures. An enhanced single-pole thermocouple technique was used to measure the actual contact temperatures in deep cutting. The performance of conventional wheels is depicted together with the performance of a CBN wheel obtained from actual industrial tests.

An Innovation System for Building Manufacturing

Traditionally the construction sector is very conservative, risk averse and reluctant to adopt new technologies and ideas. The construction industry faces great challenges to develop more innovative and efficient solutions. In recent years, significant advances in technology and more sustainable urban environments has been creating numerous opportunities for innovation in automation. This paper proposes a new system based on extrusion-based technologies aiming at solving some limitations of current technologies to allow a more efficient building construction with organic forms and geometries, based on sustainable eco principles. This novel approach is described through a control deposition software. Current modeling techniques focus only on capturing the geometric information and cannot satisfy the requirements from modeling the components made of multi-heterogeneous materials. There is a great deal of interest in tailoring structures so the functional requirements can vary with location. The proposed functionally graded material deposition (FGM) system will allow a smooth variation of material properties to build up more efficient buildings regarding thermal, acoustic and structural conditions.

Study of a Hydroelastic Instability Phenomenon: Flutter of Racing Yacht Keels

In the field of aeroelasticity, flutter is a well known instability phenomenon. Flutter is a synchronized vibration which takes place in a flexible structure moving through a fluid medium. It occurs when two regular, rhythmic motions coincide in such a way that one feeds the other, drawing additional energy from surrounding flow. A classic case of wing flutter might combine wing bending with either wing twisting. This article explores the flutter phenomenon in water. An important difference from the flutter phenomenon in air is the fact that the flexible structure is evolving in heavy fluid; this implies in particular added mass effects and important fluid damping. Flutter appeared for the first time on racing yacht keels with composite fins, so in water, in 2004: • On the IMOCA 60 feet boat POUJOULAT-ARMORLUX of Bernard STAMM during the transatlantic race ‘The Transat’: he lost his keel and capsized. • On the IMOCA 60 feet boat SILL Rolland JOURDAIN: the keel and the boat were saved. Following these problems — particularly following the loss of the keel of Bernard STAMM sailboat, accident that could have dramatic consequences for the skipper — HDS company focused on the phenomenon. Flutter has occurred only for canting keels with composite fins on IMOCA 60 feet and Volvo 70 feet racing yacht. The main questions asked are “Why are composite keels susceptible to flutter, and is it possible to predict and prevent this behaviour?”, then “Can a fair indication of the flutter critical speed of the keel be given at low cost?”. This presentation will introduce the strategy of HDS faced to the problem and the analytical and numerical methods implemented to estimate the flutter critical speed. Our model is based on a truncated modal basis for the most energetic modes which are generally, for a bulb keel, the lateral bending predominant mode and the torsion predominant mode. One of our requirements was to make a simple model in order to integrate the calculation of the flutter critical speed in the first design loops of a composite or steel keel. This model has worked well for the two cases of flutter appeared on IMOCA sailboat keels. Besides, to verify the quality of the model and to complete our analysis of flutter phenomenon on racing yacht keels, a 3 dimensional multi-physics simulation has been developed using the software ADINA.

Preparing for Generation Z: The Hippocampus Experiment at Ecole Centrale de Nantes

Although social researchers who have written about Generation Z have found it difficult to classify the generation precisely, “Gen Z” is generally defined as the younger children of Generation X — in other words, Gen Z starts with today’s teenagers. For the last fifteen years, technoculture theorists have been exploring the consequences of the wide availability of internet connectivity to the first generation of people born to it, who are referred to as “Digital Natives”. Their purpose is to address issues such as shifts in the concept of identity, privacy, content creation, activism, and piracy. Our objective will be to apply the findings of generational experts to highlight possible avenues for pedagogical innovation in our University of science and engineering. We cover a range of questions: What are the online behavioral differences between generation X, Y and Z? What is our experience at ECN in terms of blended teacher and student driven pedagogies? What is the role of Information and Communication Technologies (ICT) in education? What are the expectations and contributions of the “Digital Natives” likely to be? Our purpose will be to define the type pedagogical approach which has the potential to appeal to Gen Z and help them face the challenges of their generation. This paper will be based on the research and testimonies of a wide range of experts: it will include the work of technoculture theorists such as John Palfrey, Urs Gasser and Cathy Davidson as well as our own practical experience at ECN, mainly the Hippocampus project. Our purpose will be to determine how we — researchers and pedagogues — can draw on our present pedagogical experiences to prepare for generation Z1.