Mechanics of Materials I

Objectives

This curricular unit intends to give the student a set of theoretical and practical knowledge needed for the mechanical characterization of materials, whose structure and processing techniques are the subjects of other curricular units. In the end, the student should be able:

- to perform the mechanical characterization of a given material, correctly interpreting the results obtained;

- to correctly interpret the obtained results from the mechanical characterization of a given material;

- to evaluate the quality, from a mechanical behaviour’s standpoint, of a material received from a supplier or a transformed material to dispatch to a customer;

- to correctly interpret any deviations in the mechanical properties of a material, in correlation with its nature and the processing methods used for its transformation;

- to suggest any changes in the processing methods, aimed at improving the product materials and optimizing costs.

General characterization

Code

10194

Credits

6.0

Responsible teacher

Alexandre José da Costa Velhinho

Hours

Weekly - 5

Total - 84

Teaching language

Português

Prerequisites

N/A

Bibliography

George E. Dieter, “Mechanical Metallurgy”, McGraw-Hill-International Student Editions, 1982

M. F. Ashby & D. R. H. Jones, “Engineering Materials, An Introduction to their Properties and Applications”, Int. Series on Mater. Sci. & Technol., vol. 34, Pergamon Press, 1980

Teaching method

Two types of lessons will be considered: Lectures and laboratory. Lectures will be given using PowerPoint slides, students having access to copies on the course page in the Moodle platform. The laboratory work will be performed by the students under the guidance of the teacher and focus on the different topics of the syllabus.

Teaching has theoretical and experimental components that will allow students to acquire and apply knowledge to determine the mechanical behaviour of rigid materials. In lectures, the subjects will be presented and explained, which will allow the consolidation of knowledge that will later be put into practice in labs. Thus, lectures and laboratory classes complement each other in order to provide an integrated learning. Lab works assume an important role in the evaluation of the curricular unit as it is through these that students acquire skills that will allow them to master the possible application of materials in the construction of structural components.

Throughout the semester, a constant demand will be placed on knowledge previously acquired (Physics I, Physical Metallurgy and Metallography), and special care will be taken in order to establish firm bridges to subsequent curricular units (Mechanics of Materials II, Metallic Materials Forming Technologies, Thermal Treatments and Mechanical Treatments, Composites – Materials and Applications, Materials Selection).

Evaluation method

Due to the disturbance caused by health confinement due to the COVID-19 pandemic, the evaluation method initially defined suffers the following changes:

The final grade (NF) is obtained as follows:

- for the continuous assessment situation
• (A) NF = 0.50 * T1 + 0.50 * T2

- in case of passing a final exam
• (B) NF = NE

where:

• T1 and T2 are the test scores (continuous assessment)
• NE is the grade of the Final Exam.

The test scores (T1 and T2) will correspond to those obtained in remote tests, in Moodle support or another one deemed convenient by the teachers, depending on the actual conditions that are close to the date of the test; each of the aforementioned tests may, also depending on what the professors may consider more reliable, take place on a unique occasion, on the date initially stipulated in the UC test calendar, or unfold in a set of mini-tests taking place on dates neighbors of that.

If the evolution of the pandemic precludes the realization of the laboratory experiments, the UC frequency will be awarded as a result of participating in the assessment tests.

Classifications obtained in the Distance Assessment regime equal to or higher than 15 values may be subject to subsequent oral test.

For the remainder, and without prejudice to any subsequent changes that may become necessary in view of the evolution of the situation, the recommendations contained in the Annex to Order No. 04/2020, of 30 March, adopted by the Director of FCT / UN

Subject matter

Overview of materials’ mechanical behaviour:

Definitions: stress, strain; engineering and true values;
Stress and strain states;
Normal and shear stresses; normal strains and distortions;
Stress and strain tensors.

Elasticity theory:
- Hooke’s law for uniaxial states;
- Generalized Hooke’s law;
- Hooke’s law for specific cases: isotropic, cubic, transverse isotropic and orthotropic materials.
Plasticity:
- Plastic deformation mechanisms:
  - Dislocation glide and twinning;
  - Temperature and strain rate effects: superplasticity;
- Fracture:
  - Mechanisms;
  - Macro- and micrographic facies;
  - Fracture mechanics;
  - Fracture-resistant design;
- Fatigue:
  - Notched and unnotched parts;
  - Basquin’s law;
  - Paris’ law;
  - Goodman’s law;
- Creep:
  - Characteristic curves;
  - Mechanisms as affected by temperature and stress level;
  - Creep-resistant materials selection.

Programs

Programs where the course is taught:

Materials Engineering