Course detail

Nonlinear Mechanics

FAST-0D7Acad. year: 2020/2021

Types and sources of nonlinear behavior of structures. New definition of stress and strain measures that is necessary for geometrical nonlinear analysis of structures. Principles of numerical solution of nonlinear problems (Newton-Raphson, modified Newton-Rapshon, arc length). Post critical analysis of structures. Linear and nonlinear buckling. Application of the presented theory for the solution of particular nonlinear problems by a FEM program.

Language of instruction

Czech

Number of ECTS credits

4

Department

Institute of Structural Mechanics (STM)

Learning outcomes of the course unit

Not applicable.

Prerequisites

Linear mechanics
Finite element method
Matrix algebra
Fundamentals of numerical mathematics
Infinitesimal calculus

Co-requisites

Not applicable.

Planned learning activities and teaching methods

Not applicable.

Assesment methods and criteria linked to learning outcomes

Not applicable.

Course curriculum

1.Introduction to nonlinear mechanics
Physical and geometrical nonlinearities
Eulerian and Lagrangian meshes¨
2.Strain measures (Green-Lagrange, Euler-Almansi, engineering, logarithmic), their behavior in large strain and large rotation
Stress measures (Cauchy, 1. Piola-Kirchhoff, 2. Piola-Kirchhoff, Biot).
Energeticaly conjugate stress and strain measures
3.Tangent stiffness matrix
Material stiffness
Geometrical stiffness
Influence of nonlinear members of the strain tensor
4.Newton-Raphson method.
Calculation of unbalanced forces
5.Modified Newton-Raphson method
Postcritical analysis
Deformation control
Arc length method
6.Linear and nonlinear buckling
Von Mises truss, snap through
7.Physical nonlinearity (supports, beams, concrete, subsoil)
8.Types of materials, introduction into constitutive material models
Linear and nonlinear fracture mechanics.
Fracture mechanical material parameters
9.Problem of strain localization, false sensitivity on the mesh
Restriction of localization
Crack band model
Nonlocal continuum mechanics
10.Constitutive equations for concrete and other quasi-fragile materials
Fracture-plastic model
Mircroplane model
11.Influence of size to bearing capacity (size effect)
Energetical and statistical causes
Analysis of the influence of size on strength in tension in bending
12.Presentation of modeling by a software on nonlinear fracture mechanics
13.Presentation of modeling
Examples of applications
Mechanics of damage

Work placements

Not applicable.

Aims

Students will learn various types of nonlinearities that occur in the design of structures. They will understand the basic differences in the attitude to linear and nonlinear solution of structures. They will learn new definition of stress and strain measures and the principles that are necessary for nonlinear solution of structures by the Newton-Raphson method.

Specification of controlled education, way of implementation and compensation for absences

Extent and forms are specified by guarantor’s regulation updated for every academic year.

Recommended optional programme components

Not applicable.

Prerequisites and corequisites

Not applicable.

Basic literature

Computers&Structures. Willey&Sons
Int. J. for Numerical Methods in Engineering. Willey&Sons
Comp. Methods in Applied Mechanics and Engineering. Willey&Sons

Recommended reading

Not applicable.

Type of course unit

 

Lecture

26 hours, optionally

Teacher / Lecturer

Syllabus

1.Introduction to nonlinear mechanics Physical and geometrical nonlinearities Eulerian and Lagrangian meshes¨ 2.Strain measures (Green-Lagrange, Euler-Almansi, engineering, logarithmic), their behavior in large strain and large rotation Stress measures (Cauchy, 1. Piola-Kirchhoff, 2. Piola-Kirchhoff, Biot). Energeticaly conjugate stress and strain measures 3.Tangent stiffness matrix Material stiffness Geometrical stiffness Influence of nonlinear members of the strain tensor 4.Newton-Raphson method. Calculation of unbalanced forces 5.Modified Newton-Raphson method Postcritical analysis Deformation control Arc length method 6.Linear and nonlinear buckling Von Mises truss, snap through 7.Physical nonlinearity (supports, beams, concrete, subsoil) 8.Types of materials, introduction into constitutive material models Linear and nonlinear fracture mechanics. Fracture mechanical material parameters 9.Problem of strain localization, false sensitivity on the mesh Restriction of localization Crack band model Nonlocal continuum mechanics 10.Constitutive equations for concrete and other quasi-fragile materials Fracture-plastic model Mircroplane model 11.Influence of size to bearing capacity (size effect) Energetical and statistical causes Analysis of the influence of size on strength in tension in bending 12.Presentation of modeling by a software on nonlinear fracture mechanics 13.Presentation of modeling Examples of applications Mechanics of damage

Exercise

13 hours, compulsory

Teacher / Lecturer