用MAPLE解BVP遇到newton iteration not converging

lambeef

具体代码如下：
# X4 Z: |% U2 a( E* e5 ?l := 1000*10^(-9);
w := 50*10^(-9);
$ q1 ?5 v# K. N# \* ~1 U5 n$ G1 I3 hk := (1/12)*w^3;
E := 150*10^9;
d := 20*10^(-9);
7 T' n) t, a" ~% N" F5 f+ T v := 2.3;
electrostatic := 8.854*10^(-12)*v^2*(1/2);
4 Q0 Y& i% h& c; Y* u+ R% x6 {1 xode := diff(y(x), x$4) = electrostatic/((d-y(x))^2/E/k);
( }: v- S) r" V  wbcs1 := y(0) = 0, (D(y))(0) = 0, (D(D(y)))(l) = 0, (D(D(D(y))))(l) = 0;
ansl1 := dsolve({ode, bcs1}, numeric, method = bvp, abserr = 28)
" c; g% P6 I9 C0 O' }问题是求在静电场作用下，梁的弯曲问题。v是电压,当电压很小时，可以算出结果，但是电压大于1V时出现‘newton iteration not converging’. 想了很长时间做不出来，请各位帮个忙！谢谢！