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Revision 838 - (hide annotations) (download) (as text)
Fri Sep 8 06:57:55 2006 UTC (16 years ago) by johnpye
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Added beam model.
1 johnpye 838 REQUIRE "atoms.a4l";
2    
3     (* a parameterised simply-supported beam model *)
4    
5     MODEL beam_parameterised(
6     n WILL_BE integer_constant;
7     E WILL_BE youngs_modulus;
8     I WILL_BE second_moment_of_area;
9     L WILL_BE distance;
10     );
11     v[1..n] IS_A distance;
12     x[1..n] IS_A distance;
13    
14     P IS_A force;
15     a,b IS_A distance;
16     a + b = L;
17    
18     isrightp[1..n] IS_A distance;
19    
20     FOR i IN [1..n] CREATE
21     v_left[i]: v[i] = P*b/(6*E*I*L)*((L^2 - b^2)*x[i] - x[i]^3);
22     v_right[i]: v[i] = P*b/(6*E*I*L)*((L^2 - b^2)*x[i] - x[i]^3 + (L/b)*(x[i]-a)^3 );
23    
24     CONDITIONAL
25     isright[i]: x[i] > a;
26     END CONDITIONAL;
27    
28     isrightp[i] == SATISFIED(isright[i]);
29    
30     WHEN (isrightp[i])
31     CASE TRUE:
32     USE v_right[i];
33     CASE FALSE:
34     USE v_left[i];
35     END WHEN;
36     END FOR;
37    
38     END beam_parameterised;
39    
40     (*
41     Model of a simply-supported beam of length L
42     with a single vertical point load P at 0 < a < L
43     *)
44    
45     MODEL beam;
46     n IS_A integer_constant;
47     n :== 1;
48     E IS_A youngs_modulus;
49     I IS_A second_moment_of_area;
50     L IS_A distance;
51     B IS_A beam_parameterised(n,E,I,L);
52    
53     P ALIASES B.P;
54     a ALIASES B.a;
55     b ALIASES B.b;
56    
57     x ALIASES B.x[1];
58     v ALIASES B.v[1];
59    
60     METHODS
61     METHOD specify;
62     FIX E, I, L;
63     FIX P, a;
64     FIX x;
65     END specify;
66    
67     METHOD values;
68     E := 200 {GPa}; (* approx, for steel *)
69     I := 142e6 {mm^4}; (* AISC Universal Beam 360UB50.7 *)
70     L := 3.5 {m};
71     P := 14.0 {kN};
72     a := 1.75 {m};
73     x := 2.0 {m};
74     END values;
75    
76     METHOD on_load;
77     RUN reset;
78     RUN values;
79     END on_load;
80    
81     END beam;
82    

john.pye@anu.edu.au
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