F S t r

Finite Strip Computer Application




The FStr computer application program is based on the Finite Strip Method and gives to the user an easy and intuitive elastic buckling analysis, allowing access to the buckling mode shape of thin-walled structural member. Besides the generation of the 2D and 3D buckling modes illustration, the user is able to obtain the critical buckling load and its related member length.




What is FStr?

  • FStr stands for, Finite Strip Computer Application based on trigonometric longitudinal functions;

  • FStr is a software developed on the basis of the Finite Strip Method formulation;

  • The formulation uses trigonometric functions in longitudinal direction in series, with the purpose of interpolate the solution inside the strip, and form a shape suitable to any type of end boundary condition;

  • Signature curves are one type of analyze the results, through a set of longitudinal lengths. Then, the user can analyze the critical modes in any critical length;

  • 3D buckling modes, with colorful plots, helps the user to identify the critical buckling mode easily.

Easy and intuitive interface

The Graphical User Interface (GUI) is implemented in the MATLAB App Designer (MATHWORKS, 2000). The purpose of the GUI is to make it easier to the user to set up the data input and to analyze the data output.

The FStr has an accessible and easy graphical user interface, and is conceived to attend research activities as well as engineering design of thin-walled structures with arbitrary cross-sections.

Graphical User Interface Description

  1. Coordinates Panel:
[Node Number; Coordinate in X direction; Coordinate in Y direction];
  1. Elements Panel:
[Element Number; First Node; Second Node; Thickness; Material Name];
  1. Orthotropic Material Panel:
[Material Name; Transverse Elastic Modulus; Longitudinal Elastic Modulus; Minor Poisson’s ratio; Major Poisson’s ratio; Shear Modulus] (the shear modulus is optional for isotropic materials);
  1. Loading:
Compression (P); Moment about geometric X axis (Mx); Moment about geometric Y axis (My); Moment about major principal axis 1 (M1); Moment about minor principal axis 2 (M2);
  1. Automatic Cross-section generation:
I-section, T-section, C-section, Lipped Channel Section, Hat-section, Z-section, L-section, Rack section, Rectangular and Square Hollow section, Polygonal Hollow Section;
  1. End Boundary Condition:
  • C-C: Clamped-Clamped (Fixed-Fixed);
  • S-S: Simply-Simply (Pinned-Pinned);
  • C-S: Clamped-Simply (Fixed-Pinned);
  • C-G: Clamped-Guided (Fixed-Guided);
  • C-F: Clamped-Free (Fixed-Free).
  1. Half-wave terms for trigonometric series:
[1 2 3 4 5 6 7 8 … ] (one term of half wave equal to 1, for end boundary condition S-S is sufficient to acquire the critical buckling load/moment, in most of the cases)
  1. Longitudinal set of Lengths:
  • " logspace(1,4,200) " : Log spaced vector from 10^1 to 10^4, with 200 lengths;
  • " 10:100:10000 " : Linear spaced vector from 10 to 10000, with increment of 100;
  • " linspace(10,10000,200) " : Linear spaced vector from 10 to 10000, with 200 lengths;
  1. Dynamic 2D cross-section geometry
  2. About the FStr Computer Application
  3. Elastic Buckling Analysis Button
  4. Number of superior modes displayed:
[ 1 2 3 … ]
  1. Load Factor:
It can be critical stress, critical axial load or critical moment;
  1. Selection of Superior Modes
  2. Signature Curve and Superior Modes:
Load Factor versus Longitudinal Length
  1. Dynamic 2D Modal Shape:
For each Length and Transversal Position Ratio
  1. Save:
Formats: .txt or .mat
  1. Selection of Longitudinal Length
  2. Mode Scale and Interpolation points changer
  3. 3D Modal Shape for the selected Length

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