Tool for Thin-Walled Prismatic Structures What are Thin-Walled Prismatic Structures? Thin-walled prismatic structures are very common; an "I" beam is an example. Any beam of constant cross-section where the components of the cross-section (webs,flanges etc) have a length to thickness ratio of > 10 are thin-walled prismatic structures. Why a Special Tool? The basic assumptions for "solid" beams do not apply for thin-walled beams: Bernoulli hypothesis; that plane sections remain plane isn't valid. An out of plane deformation called "warping" occurs, and, also, "shear lag", may occur. Principle of Saint Venant isn't valid, i.e. two loads which might be statically equivalent can produce very different results over the entire length of the beam. Thin-walled structures are susceptible to local buckling. The stresses associated with warping can be as large or larger than bending stresses but they are frequently ignored because they are difficult to analyze. Using this program, if one has a basic understanding of the theory one can easily analyze the general case of thin-walled prismatic structures. The visualization of bimoment and warping stresses allows one to perform analyse in a way which isn't possible with general purpose finite element packages, and, models can be constructed in a minutes. Simple Illustration Consider a "Z" beam, 100 inches long, fully constrained at one end and free at the other. A force of 1000 lb is slung off a corner at the free end. See main display. In the plot, you see the variation of the bimoment over the length of the beam as well as the (dominated) Saint Venant's torsion (Msv) and warping torque (Mds). Note that the bimoment is zero at the free end, since the section is free to warp there, and that it is nonzero everywhere else (please excuse the overlapping text).If the bimoment plot is toggled off we get a better display of the torsion forces. Various section analyses, (for a more detailed discussion of this example see Oden's _Mechanics of Elastic Structures_ , Section 7.9.) Geometric section properties --- Note, that in addition to the usual section properites there are a few new ones relating only to thin-walled structure, e .g. sectorial moment of inertia and warping constant. Bending direct stresses at fixed end Bending shear stress at an arbitrary section St Venant's torsional stress at the free end (is zero at the fixed end; no twist) Warping normal stresses at the fixed end Because these stresses reach a maximum at a free edge they are important when checking for local buckling. Warping shear stress at the fixed end Total direct stress at the fixed end Total shear force at the fix end Summary of Features Latest finite element and finite strip methods for analysis of thin-walled structures Open, closed, and mixed types of cross-sections Automatic cell finding Bending , torsion forces/displacements plotted over length of beam Bending, torsion and VonMises stresses displayed for section views Non-Uniform Rational B-Splines (NURBS) are used for all geomety Modern graphical user interface Section properties Tcl scripting language Limitations This first release is limited to linear analysis of structure composed of homogeneous isotropic materials. Elastic buckling and vibration will be addressed in the follow on release. Current Version:   Beta Test License Type:   Commercial Home Site: Thin-wall Structures Corporation 7002 24th N.E. Seattle , Wa 98115 USA Contact Person: Randall Edick Telephone: (206)525-2277 E-Mail: rre9518@rre9518.seanet.com Source Code Availability: No Available Binary Packages: Debian Package: No RedHat RPM Package: No Other Packages: Yes Targeted Platforms: Linux (native), Windows 95/NT. Software/Hardware Requirements: Disk Space: 30MB, RAM: 16MB Min 24MB Recommended. Other Links: None Mailing Lists/USENET News Groups: None User Comments: None
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