









A new book and software for modeling of shells based on the KirchhoffLove theory
Available with source codes and intended for scientific and engineering research



Differential Geometry of Surfaces



The book "Computational Geometry of Surfaces and its Application to the Finite Element Analysis of Shells" by Olga Axenenko and Alexander Tsvelikh provides a theoretical introduction in differential geometry of surfaces,
as well as mathematical fundamentals of the theory of thin shells.
The principal value of the book is a completely new numerical method that allows
constructing the lines of principal curvature on any type of curved surface.
As an application of the developed method, we chose to create a new 9node finite element
and to test it on several practical shell structural problems which analytical solutions
are known.
However, the method for constructing the lines of principal curvature might be used to solve other problems which require the knowlede of a surfaces geometry.
The surface geometry is essential for the definition of a shell structure.
Our objective in Chapter 1 of the book is to introduce the main geometrical concepts
of the differential geometry of surfaces in great detail. We pay special attention to parameters of surface and explain their geometrical meaning.
The structure of Chapter 1 is as follows:
 Coordinate systems and basis vectors
 Vectors and tensors
 The metric tensor
 The first fundumental form of surface
 The second fundamental form of surface
 The discriminant tensor
 Principal directions and curvatures of a surface
 Covariant derivatives of vectors and tensors
 Orthogonal coordinate systems and orthogonal basis
 The physical components of vectors and tensors
 The coordinate systems of the lines of principal curvature
It was the intention of the authours that the book is rather selfcontained. As a result the readers can study and/or use the book without a necessity to refer to other books or information sources, i.e. just a general mathematical and mechanical engineering background
is required.
In Chapter 5 of the book we introduce a new method that allows construction of the lines
of principal curvature on arbitrary complex curved surfaces. We explain in details the corresponding algorithm and its implementation.
The lines of principal curvature constructed by our algorithm at the center of
the 9node quadrilateral shell finite element can be chosen as the coordinate curves
on the shell surface.






The coordinate system of the lines of principal curvature is particularly important
because the lines of principle curvature represent a special case of an orthogonal
coordinate system in which the espressions for the coordinate system parameters are
geatly simplified.
Since in the coordinate system of the lines of principal curvature only the diagonal
components of the metric tensor are non zeros, we can introduce the Lame coefficients.
Also, since only the diagonal components of the curvature tensor are non zeros, we can introduce main curvature values.
As a result, the governing equations of the theory of thin shells can be written in
a very simple form.
Also, QUADSHELL algorithm allows computation of the Lame coefficients and the main
curvatures, as well as their derivatives with respect to the coordinates of the lines
of main curvature at any point on the finite element.
For example, we compute the values of these geometrical surface parameters at
Gauss intergation points (of the Gauss quadrature used to compute the finite element area)
and at points on the element where we calculate the deflection and the stress resultant
forces.
QUADSHELL algorithm could be used as a basis for other methods of numerical analysis
of problems for which the knowledge of the surface parameters is needed.
The material contained in Chapter 1 and 5 the book could make the base of a course
of lectures for students.
The CD ROM, which is shipped with the book, contains the complete source code of the software program QUADSHELL written in C++ that can be immediately compiled and run.
The CD ROM also contains the User Manual as well as the input and output data files for



The book is available on Amazon as
paperback or
hardcover.



You can also order the book by contacting Computational Mechanics Australia Pty. Ltd. by email on
comecau@ozemail.com.au or
comecau1@bigpond.net.au.
To learn more about full range of our products please follow this
link.





