key: cord-0823828-xrjzhc0p authors: Krylov, E.; Egorova, O.; Gubert, A.; Devyaterikov, S. title: SIOMMS: Evolution and development date: 2020-07-24 journal: Mech Mach Theory DOI: 10.1016/j.mechmachtheory.2020.104029 sha: 2f1964a29300d2ddeb74dd4342a287bbc65a676e doc_id: 823828 cord_uid: xrjzhc0p Promotion of Machine and Mechanism Science (MMS) among young people worldwide is one of the missions of IFToMM. Conducting Student International Olympiads on MMS (SIOMMS) fully meets this mission and is considered as an essential tool for attracting talented youth to MMS as a science. The history of SIOMMS is approaching ten years. It is the right time to analyze the experience with such events. The article summarizes the experience of the first four SIOMMS, in terms of both organization and content. The topics that were included in the contest problems are described in detail. It is indicated which of the essential MMS topics were offered at each Olympiad. The article provides the texts of eight contest problems from the first Olympiad. Generalizations, conclusions, and recommendations are made regarding the procedure for conducting the Olympiads and preparing for them, which will be useful for future participants. Following its mission of promotion of Machine and Mechanism Science (MMS) among young people all over the world, the Executive Council of IFToMM in Guanajuato, Mexico, June 2009, has resumed establishing the regular Student International Olympiad on MMS (SIOMMS) [ 1 , 2 ] . Such events meet greatly one of the main challenges for IFToMM of the attraction and interest of the young generation and national communities to IFToMM and its activity [ 3 , 4 ] . Up to the moment, there is a good history of such events (see Table 1 ). On October 24-26, 2018, the recent competition was held at Pontifical Catholica University of Peru, Lima, Peru. The primary objectives of conducting SIOMMS are to motivate young people to make study and research in the field of Mechanics, Machine Design and Analysis; to reveal most talented students; and provide them with a facility for competition. The more broad and fundamental effect of the events in the aspect of society is on not less importance. During the study and preparation period as well as during the event, including the competition itself plus lectures and master-classes delivered by leading professors and researchers, the participants can acquire qualities required for a qualified mechanical engineer, such as the qualities of an analyst , researcher , designer , computing engineer , effective communicator , team-worker , openminded person , and even more [ 5 , 6 ] . The teachers involved in the process of training the participants of the competition are given the opportunity to improve their skills. They study national and foreign MMS courses and solve research problems with the most talented students. In many technical universities, there is a significant reduction in MMS academic hours. So, the role and importance of preparing and participating in such events are difficult to overestimate. As a rule, the problem sets include knowledge on seven main MMS topics. The topics and how they were presented in the contest problems are shown in Table 2 for the first four Olympiads ( + means that the topic was included). The details of the topics are given in Table 3 for every Olympiad. At the first two Olympiads, the regulation provided for a written solution of eight problems within four hours without a break. At the Olympiads in Spain and Peru, the number of tasks and the procedure for solving them were changed: five tasks were proposed for solving within two sessions of 2.5 hours each. There was an hour break between sessions. In developing International Olympiads, there is an increase in the quality of participants' preparation. Table 4 shows the results of the winner of each Olympiad as a percentage of the maximum possible number of points. Obviously, the success of the participants is affected by the complexity of the competition problems. In addition, the participants' age increases, the SIOMMS Regulations allow for the participation of both undergraduate and graduate students. Therefore, students get the opportunity to participate in such competitions several times; for example, some participants of SIOMMS2018 have already participated in SIOMMS 2016. Great experience and many years of training have a positive effect on the results. It would probably be fair (but challenging to put into practice) to differentiate the level of difficulty for participants in various categories. Preparation and participation in the Olympiads are extremely positively considered by the participants -students. Below are just some examples of feedback received from Russian students participated in competitions in different years. To achieve a result in the competition, discipline, accuracy, attentiveness, non-standard thinking, optimization of work is necessary. These qualities were developed in the MMS classes. Students get opportunities to develop and realize themselves as professionals in the engineering field. A fundamental knowledge helps in the further development of the career of successful engineers and managers. During the preparation for the Olympics, students learned a lot, grew up mentally, gained knowledge that gave potential and opportunities in their future career. https://doi.org/10.1016/j.mechmachtheory.2020.104029 0094-114X/© 2020 Elsevier Ltd. All rights reserved. Today many former participants work as designers, engineers, and researches. Some of them develop unique robotic complexes and automated lines. And they use the knowledge gained in the classroom on the theory of mechanisms and machines almost every day. Classes were held in a friendly, close-knit atmosphere. Step by step, students realized that they were becoming part of the MMS and IFToMM community. These reflections, published by students on social networks, confirm the outstanding cultural and educational significance of MMS competitions for future engineers [5] . As an example of contest problems, the texts of the tasks offered at the SIOMMS 2011 in Izhevsk, Russia are given below. In the mechanism shown (see Fig. 1 ), crank 1 rotates clockwise with an angular speed of 60 rpm and imparts a horizontal reciprocating motion to the rack 4 through the slider 2 and the rocker 3. The rocker carries the toothed sector at its end. The rocker's section BD is curved and has the shape of a circular arc. All necessary linear and angular dimensions can be read on the scheme drawn to scale K l = 0.002 m/mm. Determine: 1. Velocity and acceleration of the rack 4 when angle O 2 O 1 A is 90 º. 2. Time ratio of the rack 4 . 3. The length of stroke of the rack 4 . In the cam mechanism with a knave edge reciprocating follower, the cam 1 rotates with a constant angular velocity ω 1 , see Fig. 2 . The follower is kept in contact with the cam by a spring (not shown). The part AD of the cam's profile is an involute of the circle with radius OC , the part AB is straight, and BAC & ACO are right angles. 1. Prove that in the position shown the change of acceleration a A 2 of the follower due to the change of the cam profile curvature is given by ω 2 1 OAse c 4 θ . 2. If the mass of the follower 2 is m , write down the expression for inertia force. The location of the center of mass S 2 on the link AB (i.e., l AS2 ) is not specified. Determine kinetic energy E of the connecting rod AB in a position such that angle ϕ 2 takes extreme (maximum or minimum) value. Determine also how the expression for the kinetic energy E depends on sizes l AB and l AS2 . Kinematic analysis of a cam mechanism (geometrical method). 3 The kinetic energy of the linkage link in a given particular position. 4 Engagement of involute spur gear wheels (velocity of the slip of one tooth relative to the mating tooth at the phases of the beginning and end of engagement). 5 Kinematical synthesis of the gearbox (selection of missing numbers of teeth, with the overall gear ratio given), finding the mechanism's actual DOF (mobility). 6 Dynamics of the coulisse mechanism (setting up the differential equation of motion, balancing the coulisse's force of inertia). 7 Dynamics of the press driven by an electric motor, and equipped with a flywheel. 8 Investigation of the coulisse mechanism dynamics with the follower's equation of motion given. SIOMMS 2013 1 Structural analysis of the linkage, including identification of local degrees of freedom, redundant constraints, and dismembering the mechanism into Assur kinematic chains. 2 Kinematics of a plane four-bar coulisse mechanism (graphical and analytical solutions). 3 For one pair of external involute spur gears determining shift coefficient provided the minimum center distance and no undercut. 4 Kinematic synthesis of the slide-crank four-bar linkage based on three given positions by both graphical and analytical methods. 5 Static balancing of a five-bar planar manipulator situated in a vertical plane. 6 Kinematic investigation of a multi-link gear mechanism containing a planetary gear train and worm gear. 7 For a given cam mechanism with a flat-face follower: pressure angle in a given position, diagram of the follower's displacement, finding an analytical expression for distance from the contact point between the follower and the cam to the centerline of the follower, an analytical expression for the cam profile. 8 Reduction of forces and masses in the given mechanism, finding for the equivalent link ω max , ω min according to a given coefficient of fluctuation of angular speed, finding average power of the motor. Problem 4. Two 20 ̊involute spur gears have a module of m = 5 mm. Gear 1 has 20 teeth, and gear 2 has 40, a standard rack cuts both without shift. The gears have the coefficient of radial clearance is c * = 0,25; the addendum is equal to the module h a = m . 1. What conditions are to be satisfied for the gear ratio of two spur gears to keep constant during the whole period of teeth engagement? 2. Determine the sliding velocity V S12 of wheel 1 with respect to wheel 2 at the positions of entering and leaving the engagement. Consider the wheel 1 as a driving one, rotating making n 1 = 20 0 0 rpm. A gearbox used to drive the drum in a hoisting mechanism (see Fig. 4 ) has been destroyed because of overloading. Because the drawings of gears were lost, the only information below is available about the gearbox: √ all gear pairs have identical modules; 1. Obtain the differential equation of the mechanism motion. 2. Counterbalance the inertia force acting on the rocker 3 through attaching two identical counterweights of mass m to the wheels 1 and 4 . Determine the masses of counterweights and angular positions they must have on the wheels. Both masses should be at a distance r apart the axes of the wheels. The crank rotates at a constant angular speed of ω 1 . A machine press is driven by an electric motor, delivering power P = 2.2 kW continuously. At the beginning of the working operation, a flywheel with a moment of inertia I = 50.5 kg ·m 2 has a rotational velocity of 250 rpm. The pressing process requires 4750 J of energy and takes time of 0.75 s . Find the maximum number of pressings that can be made during 1 hour and the reduction in speed of the flywheel after each pressing. Neglect friction losses. In the cam mechanism shown in Fig. 6 , the follower 2 has the mass of m 2 = 0.1 kg. On the rise of the follower, its displacement is given by the equation s = 0 , 5 S max ( 1 − cos π q q Y ) , where q and q Y are the angles of cam 1 corresponding to a variable position and the extreme upper position, respectively. 1. What is the angular position q * of the cam when the driving moment M D takes the maximum value? 2. Find M max D with the following data: the cam rotates at a constant speed ˙ q = 100 rad / s , the length of the follower stroke (lift) is S max = 30 mm, the end of the rising phase corresponds to the cam angle of q Y = 120 º Participants relatively easily solved Problems 5 and 7 . At the same time, it happened that the topics of the kinematics of coulisse mechanism ( Problem 1 ), toothed gearing ( Problem 4 ), and dynamics of the cam mechanism ( Problem 8 ) suggested a sort of challenge for students. Participants did only a few complete and correct solutions. Typical misunderstandings and errors are highlighted in [7] . International Olympiads present a significant challenge for both participants and their tutors. One of the aspects is the difference in the specific subject content of institutional MMS study courses. MMS as a science contains a large number of topics, many of which are very specific. It is relatively difficult to master all of them equally well in conditions of limited study time. Teaching MMS in national traditions can emphasize different aspects. Therefore, for organizing successful Olympiads, it is essential to conduct a comparative content analysis of MMS courses and develop general recommendations for both authors of contest problems, and participants. It should be done soon. In preparing for the Olympiads, we recommend using textbooks and research papers (some examples can be found in [8] [9] [10] [11] [12] [13] [14] ), which offer both geometric and analytical methods for solving problems, as well as examples of computer modeling. Compendiums of Olympiad problems [15] , which summarize the contest experience, will also be useful. Since SIOMMS are held in English, it will be helpful to use multilingual dictionaries and thesauri for TMM in the training period [16] [17] [18] [19] [20] . It is advisable to provide an opportunity for students -potential participants taking a professional English course. To keep young people interested in MMS and involved in the mechanism and machine science community there is also a need to bridge the gap between textbook knowledge and recent researches both in well-established areas and within hot topics are expected to get great importance and influence in the coming years. Here the journal of Mechanism and Machine Theory plays a very important role as one of the key international instruments for technical exchange in the field of mechanism and machine science [21] . The journal publishes also articles highlighting SIOMMS issues representing common interest for MMS educators. Professor Juan Antonio Carretero (University of New Brunswick, Canada), a member of the Executive Board of IFToMM, presented a report on the topic "Appropriate design and analysis of mechanisms." The report noted that the uncertainties that are an integral element of the production and management of mechanisms are usually ignored in the analysis and synthesis of mechanisms since they are difficult to introduce into the calculation. However, the effectiveness of real mechanisms depends on the uncertainty, so there is a need for reliable methods that could reveal the mechanisms' correct parameters. Appropriate design methods based on interval analysis are developed, in particular, for the analysis and synthesis of parallel mechanisms, for example, the parallel mechanism of the 3-RRR structure. The tasks are solved to determine the manipulator's working area with the identification of singularities and other features that can guarantee the fulfillment of the required duty by the mechanism. The synthesis methods under discussion can explore the space of design parameters to determine the full set of design options for the mechanism that will ensure the fulfillment of the objective function. More information is available in [ 22 , 23 ] . Professor Andres Kecshkemethy (University of Duisburg-Essen, Germany) devoted his presentation to numerous robotics applications for the analysis and modeling of the movement of the human body. Since 2019, Professor Kecshkemethy is the IFToMM President. Thus, in addition to providing opportunities for competition, SIOMMS, as noted above, facilitate the exchange of information in the academic environment, motivate students, and make a cultural and educational influence on them. The next, fifth Student International Olympiad on MMS -SIOMMS 2020, by the decision of the IFToMM Executive Council, was to be held in October 2020 at the Kalashnikov Izhevsk State Technical University M.T. Kalashnikov (Izhevsk, Russia). But due to the global emerging COVID-19 issues, travel restrictions, and safety concerns, it was postponed. The new dates are 19-21 May 2021 in Izhevsk, Russia, so in fact, it will be SIOMMS20/21 . The reinvigoration of the Student MMS Olympiads and incorporating them in the process of solving innovation challenges for mechanism design is considered now as one of the priorities of IFToMM activity [ 3 , 4 , 24 ] . The main challenges for SIOMMS are, in our opinion, focused on the following aspects. None. Innovation challenges for mechanism design IFToMM contribution to attraction of youth to MMS development and promotion End-term message of the IFToMM president Celebrations for the 50-year anniversary of IFToMM Cultural and educational significance of MMS competitions for future engineers Bachelor of Sciences" Programs at Technical Universities Analysis of the Participant Solutions of the First Student International Olympiad on Mechanism and Machine Science Theory of Mechanisms and Machines Computer simulation of mechanisms kinematic and dynamic analysis of four degrees of freedom manipulating robot, using methods of nonlinear programming Publishing House of MSTU Theory of Machines Publishing House of Moscow State Technical University Theory of Machines and Mechanisms Student Olympiads on theory of machines and mechanisms A: terminology for the Mechanism and Machine Science Compilation of glossary of international terms in gear design Theory of Machines and mechanisms: Russian-English Dictionary -Thesaurus On terminology for the theory of mechanisms Reference-dictionary book on gearing The journal of mechanism and machine theory: celebrating 55 years since its foundation Appropriate analysis of the four-bar linkage Appropriate synthesis of a crank rocker linkage presentation Innovation challenges for mechanism design