How to change the code to Dynamic Load!!!

4 次查看（过去 30 天）
Hamid Hokmabady
Hamid Hokmabady 2017-7-25
评论： Hamid Hokmabady 2017-7-27
Hello; I exactly don't know how to change my code to perform correctly!
Here is the code which is about analyzing a 3d truss with added load to an special point!
if true
function D=DataT3D
%m number of elements
%n number of nodes
m=25;n=10;
%coordinates of nodes [(X Y Z) for each node]
Coord=[-37.5 0 200;37.5 0 200;-37.5 37.5 100;37.5 37.5 100;37.5 -37.5 100;-37.5 -37.5 100;
-100 100 0;100 100 0;100 -100 0;-100 -100 0];
%conection of the nodes [first in coordinates is the first node and ...]
Con=[1 2;1 4;2 3;1 5;2 6;2 4;2 5;1 3;1 6;3 6;4 5;3 4;5 6;3 10;6 7;4 9;5 8;4 7;3 8;5 10;6 9;
6 10;3 7;4 8;5 9]; Con(:,3:4)=0;
%Re degrees of freedom for each node (free=0 & fixed=1)
Re=ones(n,6);
Re(1:6,1:3)=zeros(6,3);
% concentrated loads on nodes
Load=zeros(n,6);
Load([1,2,3,6],1:3)=[1 -10 -10;0 -10 -10;0.5 0 0;0.6 0 0];
% uniform loads in local coordinate system
w=zeros(m,3);
% E: material elastic modules G:shear elastic modules J:torsional constant
E=ones(1,m)*1e4;nu=0.3;G=E/(2*(1+nu));
% A:cross sectional area and Iy Iz: moment of inertia
A=ones(1,m)*0.5;Iz=ones(1,m);Iy=ones(1,m);J=ones(1,m);
%St: settlement of supports & displacements of free nodes
St=zeros(n,6); be=zeros(1,m);
% All of the variables are transposed and stored in a structure array in the name of D
D=struct('m',m,'n',n,'Coord',Coord','Con',Con','Re',Re','Load',Load','w',w','E',E','G',G','A',A','Iz',Iz','Iy',Iy','J',J','St',St','be',be');
end
This code runs with another code as a function!
if true
function [Q,V,R]=MSA(D);
m=D.m;
n=D.n;
% the matrix to store K*T for each member 12*12*m
Ni=zeros(12,12,m);
% global stiffness matrix of the structure 6n*6n
S=zeros(6*n);
% element fixed end forces in global coordinate 6n*1
Pf=S(:,1);
% internal forces and moments in local coordinate system for each member
% 12*m
Q=zeros(12,m);
% element fixed end forces in local coordinate for each member 12*m
Qfi=Q;
% member code numbers* (mcn) in global stiffness matrix for each member
% 12*m
Ei=Q;
for i=1:m
% connectivity and release of the both member ends 4*1
H=D.Con(:,i);
% difference of beginning and end nodes coordinates 3*1
C=D.Coord(:,H(2))-D.Coord(:,H(1));
% member code numbers (mcn) in global stiffness matrix for a member
% 1*12
e=[6*H(1)-5:6*H(1),6*H(2)-5:6*H(2)];
c=D.be(i);
[a,b,L]=cart2sph(C(1),C(3),C(2));
ca=cos(a); sa=sin(a); cb=cos(b); sb=sin(b); cc=cos(c); sc=sin(c);
r=[1 0 0;0 cc sc;0 -sc cc]*[cb sb 0;-sb cb 0;0 0 1]*[ca 0 sa;0 1 0;-sa 0 ca];
% transformation matrix related to the
% coordinate transformation which in considering member orientation
% 12*12
T=kron(eye(4),r);
co=2*L*[6/L 3 2*L L];
x=D.A(i)*L^2; y=D.Iy(i)*co; z=D.Iz(i)*co;
g=D.G(i)*D.J(i)*L^2/D.E(i);
% local stiffness matrix for each member
K1=diag([x,z(1),y(1)]);
K2=[0 0 0;0 0 z(2);0 -y(2) 0];
K3=diag([g,y(3),z(3)]);
K4=diag([-g,y(4),z(4)]);
K=D.E(i)/L^3*[K1 K2 -K1 K2;K2' K3 -K2' K4;-K1 -K2 K1 -K2;K2' K4 -K2' K3];
% uniform loads in local coordinate system for each member 1*3
w=D.w(:,i)';
% local fixed-end force vector for a member, corresponding to external
% loads 12*1
Qf=-L^2/12*[6*w/L 0 -w(3) w(2) 6*w/L 0 w(3) -w(2)]';
% local fixed-end force vector for a member, corresponding to support
% displacements 12*1
Qfs=K*T*D.St(e)';
A=diag([0 -0.5 -0.5]);
B(2,3)=1.5/L;
B(3,2)=-1.5/L;
W=diag([1,0,0]);
Z=zeros(3);
M=eye(12);
p=4:6;
q=10:12;
% type of member release* 0 1 2 3
% M: A matrix for modifying stiffness matrix and local fixed-end force vector of a released member ends such K=M*K , Qf=M*Qf and Qfs=M*Qfs
switch 2*H(3)+H(4)
case 0;B=2*B/3; % released at both ends
M(:,[p,q])=[-B -B;W Z;B B;Z W];
case 1; % released at the beginning
M(:,p)=[-B;W;B;A];
case 2; % released at the end
M(:,q)=[-B;A;B;W];
end
K=M*K;Ni(:,:,i)=K*T;
% global stiffness matrix of the structure 6n*6n
S(e,e)=S(e,e)+T'*Ni(:,:,i);
Qfi(:,i)=M*Qf;
% element fixed end forces in global coordinate 6n*1
Pf(e)=Pf(e)+T'*M*(Qf+Qfs);
% member code numbers* (mcn) in global stiffness matrix for each member
% 12*m
Ei(:,i)=e;
end
% Deflections in global coordinate syste 6*n
V=1-(D.Re|D.St);
% f: A vector that indicates the number of degree of freedom ndof*1
f=find(V);
V(f)=S(f,f)\(D.Load(f)-Pf(f));
% Supports reactions in global coordinate system 6*n
R=reshape(S*V(:)+Pf,6,n);
R(f)=0;V=V+D.St;
for i=1:m
% internal forces and moments in local coordinate system 12*m
Q(:,i)=Ni(:,:,i)*V(Ei(:,i))+Qfi(:,i);
end
end
So here is the Question! How to change the Load to a dynamic form?? Now the code is static! it means now we put a concentrated load to a node and we get the answer which is for example displacement of other nodes based on the added concentrated load!! BUT how can we change it to a dynamic form of load which means we add a load with different values in time (ex 5seconds) to a node and get the answer of other nodes in different time steps!!
EXPERTS HELP NEEDED!
Thanks in advance

请先登录，再回答此问题。

回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Quadratic Programming and Cone Programming 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by