Mecânica do Contacto e Lubrificação

Código:

M.EM011

Sigla:

MCL

Áreas Científicas
Classificação	Área Científica
OFICIAL	Mecânica Aplicada

Ocorrência: 2021/2022 - 1S

Ativa?	Sim
Unidade Responsável:	Secção de Mecânica Aplicada
Curso/CE Responsável:	Mestrado em Engenharia Mecânica

Ciclos de Estudo/Cursos

Sigla	Nº de Estudantes	Plano de Estudos	Anos Curriculares	Créditos UCN	Créditos ECTS	Horas de Contacto	Horas Totais
M.EM	40	Plano de Estudos Oficial	2	-	6	39	162

Língua de trabalho

Inglês

Objetivos

Behaviour and design of lubricated mechanical components under contact - Gears, Rolling Bearings, Cams:

1. Understand the physical phenomena involved in the contact between surfaces in relative motion;
2. Learn the Hertzian contact mechanics theory and the EHD lubrication theory;
3. Apply tribological design criteria to mechanical components (gears, rolling bearings, cams, ...) and to select an adequate lubricant;
4. Analyse surface failures and relate them to the concepts of Contact Mechanics and EHD Lubrication.

Computational knowledge:
Analyse the contact parameters, the lubrication and the life of machine elements using the KissSys/KissSoft software.

Experimental knowledge:
Measurement of the physical and chemical properties of lubricants, surface roughness/topography, lubricant film thickness and friction in the contact, power loss in gears and rolling bearings, and lubricant degradation.

General knowledge:
Measurement of physical, chemical and mechanical parameters.

 

Resultados de aprendizagem e competências

The main goal of this course is to provide the students with the fundamental concepts of mechanical components under contact loads.

The first two topics of the course present and discuss the physical phenomena and the theories of Hertzian Contact Mechanics and EHD Lubrication.

The presentation of these concepts is followed (in extracurricular period) by laboratorial demonstrations related to the surface roughness/topography, the measurement of the physic and chemical properties of lubricants, lubricant film thickness and friction in the contact, power loss in gears and rolling bearings and lubricant degradation.

The last topic is dedicated to the application of those concepts to the design and failure analysis of typical machine elements, in particular, gears, rolling bearings and complex mechanical transmissions. The students will use specialized software (KissSoft) for the analysis of machine components.

Modo de trabalho

Presencial

Pré-requisitos (conhecimentos prévios) e co-requisitos (conhecimentos simultâneos)

Mathematics: Differentiation, integration, differential equations.

Mechanics: Kinematics and dynamics of mechanisms.

Solid Mechanics: Bi and tri-axial stress state.

Fluid Mechanics: Navier-Stokes equations.

Machine Elements: Gears, Rolling Bearings, Lubricants, Hidrodynamic Lubrication.

Software for Machine Element Design (KissSys, KissSoft).

Programa

Hertzian Contact Mechanics:

Contact between solids of revolution (Hertz Theory). Stresses inside contacting solids. Influence of surface roughness on contact. Application to gears, rolling bearings and cams.

 

Elastohydrodynamic Lubrication:

Elastohydrodynamic lubrication theory. Thickness of EHD lubricant film. Rheology of EHD lubricant film. Thermal elastohydrodynamic contact. Application to gears, rolling bearings and cams.

 

Lubrication, efficiency, gear failure:

Tribological contact between teeth of a cylindrical gear. Energy balance of a gearbox. Types and methods of gear lubrication. Lubricant selection. Gears and bearings failures. Tribological assessment of machine elements using KissSys/KissSoft software.

Bibliografia Obrigatória

Jorge Seabra; Mecânica do Contacto Hertziano, Jorge Seabra / FEUP / DEMec / SMAp, 2003. ISBN: / (138 páginas)
Jorge Seabra, Armando Campos e Alexandre Sottomayor; Lubrificação Elastohidrodinâmica, Jorge Seabra / FEUP / DEMec / SMAp / 1ª edição / 2002, 2002. ISBN: / (200 páginas)
Jorge Seabra; Engrenagens – Lubrificação, Rendimento e Avarias, Jorge Seabra / FEUP / DEMec / SMAp / 1ª edição / 2005., 2005. ISBN: / (104 páginas)
Jorge Seabra; Problemas propostos, Formulário, Folha de Cálculo e Aplicações MatLab em Mecânica do Contacto e Lubrificação Elastohidrodinâmica, Jorge Seabra / FEUP / DEMec / SMAp / 3ª edição / 2005, 2005. ISBN: / (112 páginas)
Bernard J. Hamrock; Fundamentals of fluid film lubrification. ISBN: 0-07-113356-9 (Livro de referência)
K. L. Johnson; Contact mechanics. ISBN: 0-521-25576-7
Ramsey Gohar; Elastohydrodynamics. ISBN: 0-85312-820-0
Boresi e co-autores; Advanced Mechanics of Materials, John Willey and Sons, New York, U.S.A, 1978. ISBN: 0-471-08892-7

Métodos de ensino e atividades de aprendizagem

The course runs on two lessons per week, of 90 minutes each. This typology allows the presentation of the theoretical concepts followed immediately by the analysis of case studies by the teacher and/or the students. The inexistence of gaps between the presentation of concepts and their application to case studies is the main advantage of this methodology.

 

The students, divided in groups, perform several laboratorial tests during the course related to Contact Mechanics and EHD Lubrication. Measurement of surface roughness, of physical and chemical properties of lubricants, of lubricant film thickness inside the contact, as well as the measurement of friction between contacting bodies and the determination of the corresponding Stribeck curve, and the measurement of the power loss in rolling bearings and gears. Each group will present a succinct written report about the laboratorial tests performed.

These laboratorial tests aim to put into evidence the physical phenomena studied and measure the physical parameters associated to them.

 

Each student will use the KissSys/KissSoft software to design and analyse contact problems in machine elements (gears, rolling bearings, seals and complex mechanical transmissions) and apply the concepts of Contact Mechanics and EHD Lubrication.

 

The attendance to students is available during the course along the semester, in a pre-designated timetable. During the exam period, a specific timetable is agreed with the students.

Software

Mat Lab
Kiss Soft

Tipo de avaliação

Avaliação distribuída com exame final

Componentes de Avaliação

Designação	Peso (%)
Teste	70,00
Trabalho escrito	10,00
Trabalho laboratorial	10,00
Trabalho prático ou de projeto	10,00
Total:	100,00

Componentes de Ocupação

Designação	Tempo (Horas)
Estudo autónomo	75,00
Frequência das aulas	39,00
Trabalho escrito	24,00
Trabalho laboratorial	24,00
Total:	162,00

Obtenção de frequência

Students can attend the final exam only if they achieve a minimum grade of 7.50 out of 20 in the Distributed Assessment.

Students that achieve a minimum grade of 11.50 out of 20 in the Distributed Assessment are not obliged to attend the final exam.

Fórmula de cálculo da classificação final

Distributed assessment divided into two components: Exams and Laboratorial Work

Exams (T1, T2) - two written exams during the semester. Each one of the exams has a theoretical and a practical part.

Laboratorial Work (TL) – Report of the laboratory tests, performed during extracurricular period, classified between de 0 a 20 points.

The classification of the distributed assessment (CD) is given by: CD = (0.35 x T1 + 0.35 x T2 +0.30 x TL).

Provas e trabalhos especiais

Not aplicable.

Trabalho de estágio/projeto

Not aplicable.

Avaliação especial (TE, DA, ...)

Not aplicable.

Melhoria de classificação

Not aplicable.

Observações

The lectures on Tuesdays are remote.

Link:
https://videoconf-colibri.zoom.us/j/82682291457?pwd=T0tjUUdJNFVETlB5amlEbExzNGxxZz09

ID da Reunião / ID of the Meeting: 826 8229 1457

Senha de acesso / Access code: 688590