MCM is an interactive model-building and FEM preprocesssing program designed to be used in conjunction with MCAP for model building of tensile membrane and other larger deflection structural system.
MCM allows the user to build 3D FEM models interactively. It contains many features such as editing, form-finding, load creation and manipulation for preprocessing, and general postprocessing. The program allows the user to easily view the model from an orientation. It uses on-screen menus to display all available options throughout the program session.
MCM operates at two different "command levels." The main menu contains the primary "main commands." These main commands allow access into the program's main processors. Each processor has its own unique "subcommand" menu specifically tailor to its function. There is also a set of universal (or common) commands that are available throughout the program.
MCM performs shape generation (form-finding) in two different ways, based on either prestress force or on force densities. Each method bas advantages and disadvantagees. MCM is suitable for form-finding of relatively simple system. MCAP should be used for form-finding of more complex systems.
MCAP is a large deflection finite element method stress analysis program, based on stiffness method, and designed to be used in conjunction with MCM. It is designed for both shape generation and stress analysis of large deflection (i.e. geometrically non-linear) membrane, cablenet, and frame systems.
The program presently has three basic types of 3D elements:
- Axial elements (two-noded line element)
- Membrane elements (three-noded triangular elements)
- Beam elements (six degrees of freedom per node)
The axial elements are used to model cable segments, truss elements, struts, geodesic and force density elements; in other words, elements that carry only axial loads. The membrane elements (CST elements) are used to model either (tensile only) fabric elements or (tension/compression) membrane elements. The beam elements allow modeling of large deflection bending members.
Loads are applied incrementally throughout the analysis. During each load increment, MCAP will cycle through as many iterations as requested by the user. Geometry, stress, unbalanced forces, the material stiffness matrix, and geometric stiffness matrix are all updated at each iteration.
MCAP has two operation modes: Shape generation mode and analysis mode. Shape generation mode is used to solve for prestressed equilibrium shape of the membrane and/or cablenet structures (i.e. form-finding). Analysis mode is used to perform stress analysis while subjecting the structure to various applied loads.
The program I used to know was not that user-friendly. I haven't got a chance to see the latest version. The operation was tedious then. At least 3DMS was faster than MCM in terms of model-building, if you handle the program skillfully:). I will manage to give a brief description of the basic operations later. Kind of tie-up this week. Sorry.
(a). Sketch on paper what you are doing and think it out the best you can. Plan where you need key nodes to define the model; define the coordinate system (right hand Cartesian), and; computer the key nodes coordinates. Think about the mesh density you need (always use as coarse a mesh as you can to start with).
(b) Enter the key node coordinates in the "Mesh Generator,", then construct your mesh.
(c) Define the boundary conditions (D.O.F.'s) and either the prestress forces or the force densities.
(d) Perform some preliminary shaping (form-finding) and study the shape.
(e) Modify the model as you like in "Edit," "Modify," etc. Change prestress forces as required.
(f) Re-shape and study the model
(g) Add material and section properties.
(h) Save the file, leave MCM, and run your model MCAP for further shaping or checking.
(i) Once you are satisfied with your model, set the shape code in the data to 0 (for analysis) and analyze it in MCAP with prestress and dead load forces only. This is done to check the prestress/dead load equilibrium state.
(j) Print out the report output file from the MCAP run and check all of your data!
(k) Use the "MCM Load Creation" commend to assemble load cases, then go back to MCAP for analysis processing of these files.
(l) Write out a DXF file of your model and export it to other software programs, CAD, etc.
- Number of nodel points in the model
- Number of beam elements in the model
- Number of axial elements in the model
- Number of membrane elements in the model
- Shape generation code:
1=Shape generation mode. Program will maintain constant element prestress froces in all "constant force type" elements regardless of element strain.
0=Analysis mode. Element forces change proportionally with strain according to element material properties.
- Unit code (1=feet/pound, 2=meter/kiloNewtons, 3=Unitless for any consistent system of units)
Nodel point Data
-Node numbers
-Degree of freedom code for the X,Y,Z transitional, and rotational directions, respectively. 1=free to move, 2=fixed against movement.
Beam Element Data
Data Set 1
-Number of material property set
-Number of geometric proerty (i.e., section property) sets
-Number of end release sets
Data set 2 (Material property(Elastic modulus, poisson's ratio, unit weight)
Data set 3 (Area, torsional moment inertia, sectional moment inertia etc)
Data set 4 (End release : 0=moment continuity; 1=pinned)
Data set 5 (Element connectivity,I, J node numbers, material, section,end release pattern, axial force in element, bending moment in element etc.)
Axial Element Data
-Element No.
-Node number at two ends
-Cross-sectional area, elastic modulus, unit weight, prestress force
-Element type:
0=cable, constant force during shaping. Real elastic cable during analysis.
1=strut, Tension or compression elastic strut, during shaping and analysis
2=constant length cable, real elastic cable during shaping and analysis.
3=Geodesic element, geodesic element during shaping. Ignored in analysis.
4=Force density surface grid. Do not use in MCAP
5=Force density cable. Do not use in MCAP
-Force density (unit=force/length).
Membrane Element Data
-Property sets
-Membrane inflation pressure factor.
-Elastic modulus in local directions, 1 & 2
-Poisson's ratio(12) and poisson's ratio (21)
-Shear modulus (unit=force/unit length)
-Unit weight (unit=force/unit surface area）
-Element connectivity (Node I, J & K)
-Material property set number assigned to element.
-Wind coefficient
-Snow coefficient
-Prestress force in local direction #1 (unit=force/unit length)
-Prestress force in local direction #2 (unit=force/unit length)
-Membrane element type
0=constant strain, plane stress fabric membrane. Carries tensile loads only.
1=Constant strain, plane stres "plate" element. Carries tension and compression, (no bending capacity)
Applied Nodal Load Data
-Node number with applied nodal load.
-X, Y and Z- component of applied nodal load
-Moment applied about X-, Y- and Z-axis
-Number of load increments
-Minmum allowable cable forces for Cable Elements. If any cable element forces drops below the "minimum allowable cable force", the program will interpret the element to be "slack". Adjustment in stiffness to soften or remove slack elements will be made by the progarm.
-Minimum allowable membran stress (units=force/unit length). Similar to above.
There isn't that much that I can tell you. It is a finite element analysis program can incoperate cable element, fabric element with conventional elements.
