LMU432 Machine elements lp2 HT20 (7.5 hp)
The course is offered by the Department of Industrial and Materials Science.
The aim of the course is to expand the knowledge of existing machine elements which is of central importance in mechanical engineering. The course will provide a structured approach to understand and design the machine elements. In particular, the machine elements will be studied from modeling and analysis with respect to mechanics, strength theory, materials technology, and mathematics. Training an analytical understanding also increases the creative ability to create new products that meet the functional requirements that are in demand.
In addition to pure factual knowledge, important engineering skills are also needed:
- to make assumptions and approximations independently,
- to structure complex problems on one's own,
- to deal with problems that lack a clear and unambiguous solution.
Special attention is drawn to mechanical transmissions.
The course is organized as a set of modules shown in the following figure.
The course includes module lectures (FÖ), problem-solving sessions (RÖ), and construction assignments (KU). Each module topic will contain pre-recorded videos and the different activities will be carried online through Zoom. The learnings from the lectures and pre-recorded videos will be applied to solve problems for the respective topic in the module. Further, three construction assignments are provided to practice in-depth training. The knowledge is examined by the construction assignment presentation and a final written exam.
The theme for the various lectures is shown in the attached activity schedule. The purpose of the lectures is to introduce the various machine elements with regard to functional requirements, embodiments, typical performance, etc. and to go through certain theories for calculating machine elements. Problem-solving of arithmetic exercises is demonstrated in connection with the lectures. Some lectures are set aside to demonstrate the solution of previous exams. All material does not have time to be explained in detail in the lectures, but as a compliment, you should definitely read for yourself in the course literature
Note: Video lectures have been recorded. At the scheduled lectures, a shorter summary of the material is given. It is assumed that you have watched the video lectures.
Construction assignments (KÖ)
The construction exercises are labor-intensive exercise. During the design exercises, the ability to analyze and calculate as well as the presentation of one's own work are trained in a systematic and efficient manner. Expect that the design exercises will take a lot of time but at the same time also give you very good skills, which makes you well prepared for the exam. The three (3) design tasks that will be performed are:
KU1: Krymp och pressförband (Shrink and press fits)
KU2: Skruv-transmissioner (Linear transmissions)
KU3: Planetväxlar (Planetary Gears)
Guidelines for the design exercises are given in a separate memorandum. Sign up for a design exercise group via Canvas.
Extra Konsultation (RÖ)
The extra consultation is based on self-employment and the assistants supervise needs. Theis is a good opportunity to "get started" with exercises on your own. Try to solve some tasks on your own in parallel with the lectures. Then use these opportunities to ask questions and discuss variants of solutions!
The course schedule is updated in Module M0: Kursinformation.
The zoom links are present in the zoom tab on the Canvas page.
Learning objectives and syllabus
The general learning objectives of the course are:
- Describe the principal mode of operation and characteristic properties of the various machine elements.
- Apply calculation methods and dimensioning criteria for the treated machine elements.
- Select the appropriate machine element and design depending on the conditions and operating situation.
- Construct the desired functions with the treated machine elements.
- Identify opportunities for design improvements through proper use of the treated machine elements.
- Present complete analysis and calculations from design exercises in technical calculation reports.
The learning objectives from specific modules are:
M2: Bearings (sw. Lagringslement)
- Understanding the function and be able to carry out a simple analysis.
- Construct a bearing with a guide and free-running bearings.
- Select bearing type depending on application (ball, roller, spherical, conical, or angular contact bearing).
- Describe the main advantages and disadvantages of roller bearings compared to hydrodynamic bearings (plain bearings).
- Calculate equivalent bearing load, P.
- Calculate bearing life, nominal according to ISO and according to the new theory with regard to lubrication conditions (a_SKF).
M3: Bolted joints (sw. Skruvförband)
- Identify a screw connection components.
- Describe different principal types of screw joints.
- Explain the function and principle of screw connections by drawing up a principal F-δ diagram.
- Explain the difference between computational and structural rigidities. Calculate screw stiffness and component stiffness.
- Calculate pretension force, screw force, and component force.
- Calculate when a gap occurs and compensate for this.
- Select different strength classes on screws (quality classes, 4.6, 8.8, 10.9, 12.9) with regard to fatigue (mean and amplitude stresses). Explain the differences, advantages, and disadvantages of the different strength classes.
- Calculate the relevant stresses in screw connections.
- Calculate the tightening torque for a given axial force (friction number and base contact).
M4: Springs (sw. Fjädrar)
- Determine/calculate the required spring constant from external requirements.
- Explain how elastic deformations and stress are used for energy storage or power absorption. Describe standards for design and dimensioning (fatigue).
- Be able to apply approaches when dimensioning.
- Calculate spring stiffness for push/pull or rotation of coil spring.
- Calculate arising stresses, shear, and efficiency (due to curvature).
- Check the risk of cracking and the risk of bottling
- Dimension a suitable spring based on boundary conditions for function. Calculate the required linear spring constant and bias for the same application.
- Calculate free length and risk of cracking.
M5: Brakes (sw. Bromsar)
- Explain the main advantages and disadvantages of disc brakes.
- Be able to apply the required equations to describe a deacceleration process. Determine the required braking torque.
- Be able to apply Archard's abrasion law to calculate the pressure distribution due to wear in disc and rear brakes.
- Be able to apply balances for brakes with (surface) integrals.
- Calculate braking torque, application force, and the position of the applicator for disc brake
- Be able to apply energy or power balance to calculate the temperature increase in a brake.
M6: Gear transmissions (sw. Kuggväxlar)
- Understanding the function and also be able to carry out a simple analysis.
- Explain the main advantages and disadvantages of gears compared to the pulley drive.
- Calculate the gear ratio.
- Explain the concept of the module.
- Calculate reference axis distance.
- Select module and gear ratios to create the desired gear ratio (simple dimensioning / design of non-profiled offset gear).
M7: Belt transmissions (sw. Remväxlar)
- Describe the function of a belt pulley
- Describe different belt types and standards.
- Describe different variants of pretension for belt gears. Different possible construction methods/principles.
- Explain the main advantages and disadvantages of belt pulley compared to gears.
- Explain why the gear ratio for a belt gear is not completely accurate/synchronous.
- Be able to apply (draw) torque and power balances.
- Calculate the required stress. Explain that a belt gear is a power transmission and therefore requires preload.
- Apply Eytelwein's equation.
- Explain how the apparent friction number is used for the V-belt.
M8: Planetary gears (sw. Planetväxlar)
- Describe the function of planetary gears.
- Calculate and dimension the planetary gear based on requirements.
M9: Linear transmissions (sw. Skruv-transmission)
- Describe the function of power screws.
- Calculate and dimension the power screws based on requirements.
M10: Shrink and press fits (sw. Krymp och pressförband)
- Describe the function of shrink and press fits.
- Calculate and dimension the shrink and press fits based on requirements.
- Describe the difference between shrink and press joints.
- Calculate the required temperature difference when fitting a shrink joint.
- Calculate the maximum transferable load without risk of slipping.
- Calculate the required pressing force when fitting a press joint.
- Calculate the required contact pressure in a shrink/fit (KP) joint.
- Calculate the grip for a required contact pressure in a shrink/fit (KP) joint.
- Dimension shrink/fit (KP) joints without risk of slipping and maximum generated equivalent stress.
M11: Couplings (sw. Kopplingar)
- Understanding the function and be able to carry out simple analysis on couplings.
- Calculate transferable torque as a function of applicability for different pressure distributions.
- Explain Archard's wear law, show pressure distribution for worn coupling
M12: Gearboxes (sw. Växellådor)
- Describe the function of gearboxes.
- Calculate and dimension the gearboxes based on requirements
- Machine Elements - Beta version, selected chapters, and from the Swedish textbook. Can be downloaded from Canvas.
Mart Mägi, Kjell Melkersson, Magnus Evertsson, Studentlitteratur AB, Utgåva 1, 2017, ISBN: 9789144109053
- Maskinelement - Övningar
- SKF Katalog Rullningslager, utgåva 10k (2014) - via Canvas
- Construction tasks (3 pcs) - distributed via Canvas
- The examination consists of a written exam (Grade, TH), three construction assignments (Pass/Fail), and guest lectures.
- The well-presented construction assignment can yield up to 3 bonus points (1 each) which are valid for one year.
- The exam includes 5 assignments of 10 credits each. The regular exam runs 13/1-21 from 8: 30–13: 30. For passing, at least 20 points are required (bonus points included). Grading limits are given below:
|3||20 - 29|
|4||30 - 39|
Changes made since the last occasion
- All teaching will take place at a distance.
- The examiner of the course is changed.
- The course has been organized more clearly in modules.
- Video lectures have been recorded.
- At the scheduled lectures, a shorter summary of the material is given. It is assumed that you have watched the video lectures.
Magnus Evertsson, Examiner and Lecturer
Göran Brännare, Teacher
Kjell Melkersson, Teacher
Erik Hulthén, Teacher
Kanishk Bhadani, Course Administration
The syllabus page shows a table-oriented view of course schedule and basics of course grading. You can add any other comments, notes or thoughts you have about the course structure, course policies or anything else.
To add some comments, click the 'Edit' link at the top.