Harmonic Resonance Frequency Factor of Spur Gear System and Oscillation Reduction Approaches

In this study, a non-linear time-varying dynamic model of a spur gear pair system is used to investigate the dynamic behavior of the system by means of multiple scale approach. Both time-varying stiffness, transmission error and tooth backlash clearance of the system are taken into account in the model. The mesh stiffness fluctuation is developed as high order Fourier series and tooth backlash clearance is fitted by high order polynomial function. The frequency factors of the system are investigated and the frequency-response equations at the case of internal and external excitation, parametric excitation and combined excitation are obtained. The peak value of the amplitude of the primary resonance, super and sub harmonic resonance and combination harmonic under internal, external and parametric excitation are researched. The approaches of vibration reduction are investigated. Finally an example is investigated using the presented process and the results indicate the sensitivity and correctness of the presented analysis approaches.

A Review on Oil and Gas Pipeline Safety

The safety of oil and gas pipelines has increasingly considered day by day to their vulnerability. Pipelines play a very critical role in the transportation of oil and natural-gas. As they have become the veins of oil industries, the productive design and analysis became more important. This made them more vulnerable to terrorist attacks. Although it is impossible to design pipelines to withstand any conceivable damage due to external (terrorist attacks, seismic effects) and internal effects (design and manufacturing defects), it is possible to improve the performance of pipelines. By understanding the design criteria, it saves lots of money and more over human lives and also protects the product in pipelines, which cannot be recovered and which is more and more scares day by day. This research aims: 1) to understand the different types of pipeline damages, reasons for their occurrence and their effects on the pipelines, such as mechanical damages, material defects, cracks, manufacturing defects, 2) to understand the explosions in pipelines, internal or external explosions and seismic distress, 3) to do research and literature review in analytical and numerical methods which allow researching the influence of shock waves (explosions, seismic), 4) to develop description of experimental research of pipelines subjected to shock waves (explosions, seismic), 5) to establish an effective methodology (develop mathematical model) to study the risk management in pipeline exploitation which can be subjected to such conditions like shock waves (caused by explosions, seismic, as well as mining activities) on pipeline systems (buried, on surface, or underwater), and 6) to establish criteria for risk management. This paper includes a review of the related literature covering the first two goals.

Natural Frequencies of Stiffenened and Unstiffened Laminated Composite Plates

In this study, the free vibration of laminated composite plates with and without stiffeners subjected to axial loads is carried out using finite element method. The plates are stiffened by laminated composite strip and Timoshenko beam. The plates and the strips are modeled with rectangular 9 noded isoparametric quadratic elements with three degrees of freedom per node and the Timoshenko beam is modeled with linear 2 noded isoparametric quadratic elements with 2 degrees of freedom per node. The effects of both shear deformation and rotary inertia are implemented in the modeling of plate and stiffener. The governing differential equations are obtained in terms of the mid-plane displacement components and shear rotations using Hamilton’s principle. The effects of axial tension and compression loads and stiffeners on the natural frequencies of the plate are investigated. Results indicate the tension loads and stiffeners will increase the natural frequencies while the compression loads reduce the natural frequencies. The buckling force of plate is computed by increasing the absolute value of compressive force until the first natural frequency tends to zero. Results of simple cases are compared with finding in the literature and a good agreement was achieved.

Thermodynamics From a Few Dynamic Particles Raises Questions as to How Temperature and Entropy Should Be Perceived and Defined

In a recently developed simple particle mechanics model, in which a single particle represents the working fluid, (gas) in a heat engine, (exemplified by a piston engine) a new approach was outlined for the teaching of concepts to thermodynamic students. By mechanics reasoning, a model was developed that demonstrates the connection between the Carnot efficiency limitation of heat engines, and the Kelvin-Planck statement of Second Law, requiring only the truth of the Clausius statement. In a second paper the model was extended to introduce entropy. The particle’s entropy was defined as a function of its kinetic energy, and the space that it occupies, that is analogous to that normally found in classical macroscopic analyses. In this paper, questions are raised and addressed: How should temperature and entropy be perceived and defined? Should temperature be proportional to average (molecular) translational kinetic energy and should entropy be dimensionless?

An Experiment in Design and Materials: Undergraduate Students Designing Test Machines

An exercise has been developed for an undergraduate design laboratory. In the exercise, students design, build, and test load cells, then build computer interfaced tensile testing machines in which the load cells are integrated. Data is acquired through the use of a simple, low-cost bridge amplifier and digital counter circuit which was developed for this exercise. The circuit design and software are released as an open source project to encourage widespread use and participation by the academic community. The tensile test machine exercise has been tested on a group of 45 junior-level mechanical engineering students, with significant success in students demonstrating an understanding of the principles taught. The open source interface is being adopted by other courses and student projects at the host University; use at other institutions is encouraged.

Dedicated Workshops to Educate T-Shaped Engineers

Technical Innovation covers the process of creating a new successful competitive product from invention to production and market introduction within a practical company related context. Typically education for this kind of complicated, open ended work requires mastering a wide range of knowledge-areas and a lot of hands-on training practice in projects and workshops. The combination of depth and width is symbolized by the “T-shape”. Well-known learning theories give a good rationale of the teaching approaches that were developed over the years and a confirmation of this approach, including the important role of the experienced tutor, is found in the study of excellent companies. Work of a “T-shaped” engineer in the technical innovation process bears many similarities to the ideal transformation process of a company, like Collins describes in his “Good to Great”. The processes have a very comparable open-ended character, a focus for essence and simple, elegant solutions, opportunities and inventions. Success seems to rely more on the right people and a concentrated shared-goal driven cooperation (“flow”), than on the right methods of work. Collins’ observations and conclusions, applied to the domain of engineering design education helps understanding the earlier reported 15 years success of the International Product Design Engineering (IPDE) course of the Hanze University Groningen, with its combination of lecturing, projects and workshops, with a high reality content and direct supervision. The IPDE-related “Open Dynamic Design” (ODD) project and the educational experiments showed similar observations. Essential is the committed experienced participation in real innovation projects and intensive workshops, lead by very experienced T-shaped supervisors/“masters”, having deep knowledge over a good part of technologies, entrepreneurial and/or design related issues and good understanding of interrelationship and consequences in the other fields. They also should have a track record on the methodologies of product innovation and product development. Like the Collins level-5 leaders, they should be able to be both creative and analytical, give the students freedom and control them at the appropriate moments. They power the theoretical most effective learning “circle” with focused introductions and assignments, their direct, knowledgeable and adequate feedback, and quiet help during contemplation. Then the workshops are really fun and effective. The Loughborough and Glasgow Design engineering courses, the new master course at the Innovation Centre of the University of Technology of Compiegne (UTC) and the one at the Hanze Institute for Technology — an upgrade from IPDE — are built on these insights. To safeguard the continuation of this approach, a pool of experienced and potential (home and guest) T-experts is founded together by the small group of universities and their industrial partners, working jointly in the workshops, projects and modules, training the trainers while training the students - in T-design.

Collaboration of Technical Editing Students With Mechanical Engineering Seniors in a Capstone Design Course

An innovative capstone design course titled “Design of Fluid Thermal Systems,” involves groups of seniors working on various semester-long design projects. Groups are composed of 3 or 4 members that bid competitively on various projects. Once projects are awarded, freshmen enrolled in the “Introduction to Mechanical Engineering” course are assigned to work with the senior design teams. The senior teams (Engineering Consulting Companies) function like small consulting companies that employ co-operative education students; e.g., the freshmen. In Fall 2006, the Engineering Consulting Companies also worked with students enrolled in a Technical Editing (TE) course—“Writing and Editing in the Professions”—within the English Department. The TE students would be given reports or instructional manuals that the Mechanical Engineering (ME) students had to write as part of their capstone project, and the resulting editing of their documents would be done by these TE students. Subsequently, the ME students were given a survey and asked to comment on this experience. In addition, the TE students were also surveyed and asked to comment as well. It was concluded that the collaboration should continue for at least one more cycle, and that the TE students were more favorably inclined toward this collaboration than were the engineering students.

Incorporating Rapid Prototyping Machine in Teaching Mechanical Engineering Design

There is a trend toward increasing exposure of students to hands-on experience in mechanical engineering design courses as these courses are usually limited to generating calculations and drawings of mechanical designs. Students in these courses may lack the ability to visualize and create the physical objects that correspond to their calculations. This limitation may negatively affect students, especially those with limited hands-on experience. To address this issue, the Department of Mechanical Engineering, University of Nevada, Las Vegas (UNLV) started requiring students to create their design using a rapid prototyping machine as a part of the Mechanical Engineering Design Course (ME 440). Students in this course work in teams to create projects starting from abstract statements. They are required to use their calculations as a means to create solid models of the components of their designs and print them on the rapid prototyping machine. Such an approach results in a better understanding of the functionalities of components as well as fit and tolerance issues. Student feedback is used as well as future venues for improving the course.

A Comparison of Two Different Strategies for Undergraduate Research Within the Framework of a Rotor Dynamics Laboratory

Introductory graduate level courses and upper division technical electives often present a student with his or her first research project. Time limitations of a course require a balance between open ended discovery, development of specialized technical knowledge, and teaching the mechanics of research methodology. The case study presented in this paper is an outline of two different strategies to introduce research to undergraduate students within the framework of a rotor dynamics laboratory. The laboratory had historically been designed to demonstrate machinery malfunctions in a series of short exercises. The laboratory was changed to have several introductory labs designed to prepare students for an extended self-directed research project that included literature searches, paper reviews, design of experiments, and presentation of research findings to the class. In one strategy the students were expected to practice discovery primarily through experimentation with specific, restricted goals. In the other strategy the students were given more flexibility defining the research question and in establishing priorities. Both projects had students design an experiment whose results were compared to mathematical simulations and each led to research that was presented at a conference. Although both were considered successful in terms of student learning and research outcomes, a balance biased toward experimentation and restricted student options for discovery actually led to broader research findings and more in-depth student research but with less student appreciation for and practice with the necessary preliminary stages of conducting research. The student learning experiences and methodologies for each scenario are presented and compared in this paper.

Internet Based Lab Framework Development for Distance Learning in Robotics and Mechatronics Education

A number of Internet-based educational tools have been developed to support mechanical education with Internet-based technologies. However, many of these tools have limitations as mostly just visual assistant tools for understanding engineering lectures. This paper describes lab framework development integrated with Internet-based robotics and mechatronics for mechanical education. The development efforts include advanced course and laboratory activities integrated with sensor networks and Internet-based technologies. The instructional materials for Internet-based robotics and automation education utilize Robotics and Mechatronics lab as the experiments of choice. The new Internet-based techniques allow the remotely situated students to program, control, and monitor the mechanical operations through the Internet. The architecture of the Internet-based lab focusing on remote data acquisition and measurement, as well as industrial control and automation applications, is illustrated. Implementation of a remote robotic vision feedback control lab is also described.