%?example?exd1
%----------------------------------------------------------------
%?PURPOSE?
%????Set?up?the?fe-model?and?perform?eigenvalue?analysis
%????for?a?simple?frame?structure.
%----------------------------------------------------------------

%?REFERENCES
%?????G“oran?Sandberg?1994-03-08?
%?????Karl-Gunnar?Olsson?1995-09-29
%----------------------------------------------------------------
?echo?on

%?------?Generate?the?model?------------------------------------------

%?------?material?data?------------------------------------------
E=3e10;?????????????????rho=2500;
Av=0.1030e-2;???????????Iv=0.0171e-4;?????????????%?IPE100
Ah=0.0764e-2;???????????Ih=0.00801e-4;????????????%?IPE80
epv=[E?Av?Iv?rho*Av];???eph=[E?Ah?Ih?rho*Ah];
%?------?topology?-----------------------------------------------
Edof=[1???1??2??3??4??5??6
??????2???4??5??6??7??8??9
??????3???7??8??9?10?11?12
??????4??10?11?12?13?14?15];
%?------?list?of?coordinates??-----------------------------------
Coord=[0??0;?0??1.5;?0??3;?1??3;?2??3];
%?------?list?of?degrees-of-fredom??-----------------------------
Dof=[1??2??3;?4??5??6;?7??8??9;?10?11?12;?13?14?15];
%?------?generate?element?matrices?assemble?in?global?matrices?-?
K=zeros（15）;?????M=zeros（15）;
[ExEy]=coordxtr（EdofCoordDof2）;
for?i=1:2
??[kmc]=beam2d（Ex（i:）Ey（i:）epv）;
??K=assem（Edof（i:）Kk）;??M=assem（Edof（i:）Mm）;??
end
for?i=3:4
??[kmc]=beam2d（Ex（i:）Ey（i:）eph）;
??K=assem（Edof（i:）Kk）;??M=assem（Edof（i:）Mm）;??
end
?

%?-----?Draw?a?plot?of?the?element?mesh?--------------------------


clf;?????eldraw2（ExEy[1?2?2]Edof）;
grid;????title（‘2-D?frame?Structure‘）?

%?-----?Eigenvalue?analysis?--------------------------------------

b=[1?2?3?14]‘;
[LaEgv]=eigen（KMb）;
Freq=sqrt（La）/（2*pi）;


%?-----?plot?one?eigenmode?---------------------------------------

figure（1）????clf?????grid?????title（‘The?first?eigenmode‘）?
eldraw2（ExEy[2?3?1]）;?
Edb=extract（EdofEgv（:1））;??????eldisp2（ExEyEdb[1?2?2]）;
FreqText=num2str（Freq（1））;???????text（.51.75FreqText）;

%?-----?plot?eight?eigenmodes?------------------------------------

figure（2）?clf?axis（‘equal‘）?hold?on?axis?off
magnfac=0.5;
title（‘The?first?eight?eigenmodes?（Hz）‘?）
for?i=1:4;
??Edb=extract（EdofEgv（:i））;
??Ext=Ex+（i-1）*3;????????????????eldraw2（ExtEy[2?3?1]）;?
??eldisp2（ExtEyEdb[1?2?2]magnfac）;
??FreqText=num2str（Freq（i））;?????text（3*（i-1）+.51.5FreqText）;
end;
Eyt=Ey-4;?
for?i=5:8;
??Edb=extract（EdofEgv（:i））;
??Ext=Ex+（i-5）*3;????????????????eldraw2（ExtEyt[2?3?1]）;?
??eldisp2（ExtEytEdb[1?2?2]magnfac）;
??FreqText=num2str（Freq（i））;?????text（3*（i-5）+.5-2.5FreqText）;
end

%?--------------------?end?---------------------------------------
echo?off

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----

?????文件???????2725??2000-11-06?14:43??exd1.m

?????文件???????2203??2000-11-06?14:43??exd2.m

?????文件???????2050??2000-11-06?14:43??exd3.m

?????文件???????2324??2000-11-06?14:43??exn2.m

?????文件???????1313??2000-11-06?14:43??exs1.m

?????文件???????1618??2000-11-06?14:43??exs2.m

?????文件???????2527??2000-11-06?14:43??exs5.m

?????文件???????2061??2000-11-06?14:43??exs6.m

?????文件???????1744??2000-11-06?14:43??exs7.m

-----------?---------??----------?-----??----

????????????????18565????????????????????9