【求助】用sap算一水缸上环形铁箍。

用sap 计算水缸上的一个环形的铁箍，如下图： 下载 (1.23 MB)
2009-9-7 21:09


计算模型如下： 下载 (812.6 KB)
2009-9-7 21:09


有如下结果：
（弯矩） 下载 (812.6 KB)
2009-9-7 21:09


（轴力） 下载 (879.54 KB)
2009-9-7 21:09



现有如下问题:

1.0 分析时有一段话 如下，
B E G I N A N A L Y S I S 2009/09/04 15:47:19
MAXIMUM MEMORY BLOCK SIZE (BYTES) = 31.905 MB
NUMBER OF JOINTS IN THE MODEL = 8
E L E M E N T F O R M A T I O N 15:47:19
NUMBER OF FRAME ELEMENTS FORMED = 8
L I N E A R E Q U A T I O N S O L U T I O N 15:47:19
FORMING STIFFNESS AT ZERO (UNSTRESSED) INITIAL CONDITIONS
TOTAL NUMBER OF EQUILIBRIUM EQUATIONS = 48
APPROXIMATE "EFFECTIVE" BAND WIDTH = 15
NUMBER OF EQUATION STORAGE BLOCKS = 1
MAXIMUM BLOCK SIZE (8-BYTE TERMS) = 636
SIZE OF STIFFNESS FILE(S) (BYTES) = 5.172 KB
NUMBER OF EQUATIONS TO SOLVE = 48
* * * W A R N I N G * * *
NUMERICAL PROBLEMS ENCOUNTERED DURING EQUATION SOLUTION:
TYPE LABEL DOF X-COORD Y-COORD Z-COORD PROBLEM VALUE
----- ------- -- ----------- ----------- ----------- ------------- -----------
Joint 5 UX .000000 78.740157 .000000 Lost accuracy 15.5 digits
Joint 5 UY .000000 78.740157 .000000 Diag = 0 --> 1.00E-10
Joint 5 UZ .000000 78.740157 .000000 Lost accuracy 15.5 digits
Joint 5 UZ .000000 78.740157 .000000 Diagonal < 0 -3.55E-15
Joint 5 RX .000000 78.740157 .000000 Lost accuracy 15.0 digits
Joint 5 RX .000000 78.740157 .000000 Diagonal < 0 -4.09E-12
Joint 5 RY .000000 78.740157 .000000 Lost accuracy 14.5 digits
Joint 5 RY .000000 78.740157 .000000 Diagonal < 0 -7.73E-12
Joint 5 RZ .000000 78.740157 .000000 Lost accuracy 12.5 digits
* * * W A R N I N G * * *
EXCESSIVE LOSS OF ACCURACY WAS DETECTED DURING THE SOLUTION OF EQUATIONS
NUMBER OF DIGITS LOST EXCEEDED 11.0
* * * W A R N I N G * * *
THE STRUCTURE IS UNSTABLE OR ILL-CONDITIONED !!
CHECK THE STRUCTURE CAREFULLY FOR:
- INADEQUATE SUPPORT CONDITIONS, OR
- ONE OR MORE INTERNAL MECHANISMS, OR
- ZERO OR NEGATIVE STIFFNESS PROPERTIES, OR
- EXTREMELY LARGE STIFFNESS PROPERTIES, OR
- BUCKLING DUE TO P-DELTA OR GEOMETRIC NONLINEARITY, OR
- A FREQUENCY SHIFT (IF ANY) ONTO A NATURAL FREQUENCY
NUMBER OF EIGENVALUES BELOW SHIFT = 3
L I N E A R S T A T I C C A S E S 15:47:19
USING STIFFNESS AT ZERO (UNSTRESSED) INITIAL CONDITIONS
TOTAL NUMBER OF CASES TO SOLVE = 1
NUMBER OF CASES TO SOLVE PER BLOCK = 1
LINEAR STATIC CASES TO BE SOLVED:
CASE: DL
A N A L Y S I S C O M P L E T E 2009/09/04 15:47:19

这么多warning 是什么意思？是没有加支座的关系吗？

2.0 这个模型我是没有加支座的，这样可以吗？如果不可以，又怎么会分析得出结果呢？（分
析出来的结构我觉得合理）如果要加支座要加在哪里？在四个角上？为什么？

[ 本帖最后由 sharewqm 于 2009-10-5 19:34 编辑 ]