Overview about the Used Examples

-> Example overviews ->Summary of example overviews

Example Special feature

Introduction examples: - see ...\ase.dat\english\membranes

atrium.dat simple plane example with boundary cables

tennis.dat plane initial system - formfinding with internal pressure - air hall

simple_angle.dat formfinding three-dimensional initial system (angle), update with new local coordinates, internal pressure

high_point.dat simple example with high point comparison of different PTPR ratios

roof.dat three-dimensional initial system (folded structure) boundary cables, failure for large wind pressure from below

Further examples:

bottle_nec.dat same example as membhoch.dat with unstable bottleneck result

membrane_compression.datsame example as membhoch.dat with compression failure for strong wind

membran5.dat plane initial system with 4 high points and a deep point

six_corners.dat plane initial system - formfinding with constant internal pressure

tent.dat plane initial system and two high points defined as rings, unstable formfinding, soap skin, comparison with rubber

simple_angle2.dat formfinding with at first straight boundary cable, comparison four-node and three-node elements

air_volume_tennis.datAir hall with active aur volumeVOLU 2.13.9 Necessary Program Versions

For the membrane analysis the extensions ASE1 and ASE3 are necessary ad- ditionally to the ASE basic packet, for non-linear material analysis (compression

failure) also ASE4.

2.14

Dynamic Modal Analysis

For dynamic eigenvalues there are two main analysis methods available: 1. Direkt method according to Lanczos

2. Simultaneous inverse vector iteration

The method according to Lanczos is usually always the quickest one. Especially in the case of many eigenvalues (more than 10) it is the only practical method. The number of the required eigenvalues depends in turn on the expected exci- tation frequencies. The simultaneous inverse vector iteration should be used, if the interest is limited to a few eigenvalues only or if a check of the number of eigenvalues below a certain frequency is required (Sturm sequence).

The modal shapes are saved like regular load cases. They can be further pro- cessed as desired, and then they can be used chiefly with the program DYNA for a dynamic analysis.

For the simultaneous vector iteration the higher eigenvalues converge much more worse than the lower. Therefore it is reasonable, if enough memory is available, to iterate a few more vectors than one needs. The method is, howev- er, inappropriate for a large number of eigenvalues.

The number of iterations is predetermined by the program. If the convergence is slow, one should switch generally to the Lanczos method instead of increasing the number of iterations. The iteration is interrupted, if the number of the max- imum iterations is reached or if the maximum eigenvalue has changed only by the factor less than 0.00001 opposite to the previous iteration.

For the method according to Lanczos the number of the Lanczos vectors should be selected usually twice so large as the number of the desired eigenvalues. An iteration is not necessary in this case.

Example see ase4_eigenfrequencies.dat

2.15

Buckling Eigenvalues

For buckling eigenvalues only the default method with EIGE ... BUCL should be used:

The Pardiso Solver CTRL SOLV 4 should not be used here as he has problems with determinants going to 0.0. The default solver CTRL SOLV 3 is better for buckling eigenvalues.

If too many or only negative eigenvalues aer found you can choose an automatic eigenvalue shift with EIGE...LMIN AUTO. Example see

buckling_eigenvalue_shift.dat

Simple slab buckling see ase12_buckling_slab.dat

2.16

Masses

For dynamis eigenvalues only for beams consistent mass matrix are used - vgl.

CTRL MCON. All other elements use a diagonal mass matrix (lumped mass matrix). See also program DYNA.

In a time step analysis all elements use a diagonal mass matrix .

The mass center is printed in the output. The complete calculated mass vector including the dead weight can be output with ECHOLOAD EXTR.

A conversion of loads to masses can occur with the record MASSLC. Example see ase4_eigenfrequencies.dat

In earthquake analysis: a1_dynamic_overview.dat

2.17

Damping Elements

Damping values e.g. in spring elements are considered for the time-step method.

Example see spring_with_damping.dat

exponential: springdampexpo.dat

2.18

Modal Damping and Modal Loads

The modal damping dj is defined as a product of the modal shape i multiplied by

the damping matrix multiplied by the modal shape j. This matrix is not generally diagonal. However, ASE calculates only the diagonal terms of this matrix and saves them as modal damping values. Different damping of the individual modal shapes can be calculated easily in this way by specifying different damping for particular element groups.

For evaluation of modal load, SOFILOAD can multiply a loadvector of an ASE loadcase e.g. 3 with an eigenform e.g. lc 1004 (SOFILOAD: LC 3 rest ; EVAL RU no 1004).

Literature

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