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x
syms t;
x1=sym('x1(t)');
x2=sym('x2(t)');
x3=sym('x3(t)');
x4=sym('x4(t)');
x5=sym('x5(t)');
x6=sym('x6(t)');
x7=sym('x7(t)');
u1=sin(t);
u2=diff(u1);
f1=diff(x1,t,2)-1/1105*(-c11*diff(x1,t)-c12*diff(x2,t)-c13*diff(x3,t)-c14*diff(x4,t)-c15*diff(x5,t)-c16*diff(x6,t)-c17*diff(x7,t)-k11*x1-k12*x2-k13*x3-k14*x4-k15*x5-k16*x6-k17*x7);
f2=diff(x2,t,2)-1/1105*(-c21*diff(x1,t)-c22*diff(x2,t)-c23*diff(x3,t)-c24*diff(x4,t)-c25*diff(x5,t)-c26*diff(x6,t)-c27*diff(x7,t)-k21*x1-k22*x2-k23*x3-k24*x4-k25*x5-k26*x6-k27*x7);
f3=diff(x3,t,2)-1/1105*(-c31*diff(x1,t)-c32*diff(x2,t)-c33*diff(x3,t)-c34*diff(x4,t)-c35*diff(x5,t)-c36*diff(x6,t)-c37*diff(x7,t)-k31*x1-k32*x2-k33*x3-k34*x4-k35*x5-k36*x6-k37*x7-kqz*u1-kqz*u1-khz*u1-khz*u1-cqz*u2-cqz*u2-chz*u2-chz*u2);
f4=diff(x4,t,2)-1/726*(-c41*diff(x1,t)-c42*diff(x2,t)-c43*diff(x3,t)-c44*diff(x4,t)-c45*diff(x5,t)-c46*diff(x6,t)-c47*diff(x7,t)-k41*x1-k42*x2-k43*x3-k44*x4-k45*x5-k46*x6-k47*x7+(kqz*l1-khz*l2+khz*l1-khz*l2)*u1+(cqz*l1-chz*l2+chz*l1-chz*l2)*u2);
f5=diff(x5,t,2)-1/3185*(-c51*diff(x1,t)-c52*diff(x2,t)-c53*diff(x3,t)-c54*diff(x4,t)-c55*diff(x5,t)-c56*diff(x6,t)-c57*diff(x7,t)-k51*x1-k52*x2-k53*x3-k54*x4-k55*x5-k56*x6-k57*x7-2*(kqz*b1-khz*b2)*u1-2*(cqz*b1-chz*b2)*u2);
f6=diff(x6,t,2)-1/946*(-c61*diff(x1,t)-c62*diff(x2,t)-c63*diff(x3,t)-c64*diff(x4,t)-c65*diff(x5,t)-c66*diff(x6,t)-c67*diff(x7,t)-k61*x1-k62*x2-k63*x3-k64*x4-k65*x5-k66*x6-k67*x7);
f7=diff(x7,t,2)-1/100*(-c71*diff(x1,t)-c72*diff(x2,t)-c73*diff(x3,t)-c74*diff(x4,t)-c75*diff(x5,t)-c76*diff(x6,t)-c77*diff(x7,t)-k71*x1-k72*x2-k73*x3-k74*x4-k75*x5-k76*x6-k77*x7);
F1=laplace(f1)
F2=laplace(f2)
F3=laplace(f3)
F4=laplace(f4)
F5=laplace(f5)
F6=laplace(f6)
F7=laplace(f7)
拉普拉斯变换后计算出X1(S)到X7(s)，但是表示得不出解析解，想用数值解计算本人想把s=jw代入，计算频率特性，但是感觉好像不太对
各路大神，帮帮看看。或者给点建议，从频域计算振动微分方程要怎么算，求思路
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发表于 2014-7-2 21:41
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发表于 2014-7-11 10:01
