用MAPLE解BVP遇到newton iteration not converging

lambeef

具体代码如下：
( a$ d( g  x; ^7 i" N: Jl := 1000*10^(-9);
/ F" V& T' l- r4 K- x5 _* p2 T: ^w := 50*10^(-9);
4 |! _$ P' l/ V. d' T1 Wk := (1/12)*w^3;
% I5 [9 R6 s# {6 j5 h5 AE := 150*10^9;
) z) d" W0 ], S- f0 V  wd := 20*10^(-9);
v := 2.3;
% F$ N6 H" \8 f$ j6 P8 Pelectrostatic := 8.854*10^(-12)*v^2*(1/2);
  I  ]8 q6 S7 }# v7 _3 A+ X) ?ode := diff(y(x), x$4) = electrostatic/((d-y(x))^2/E/k);
bcs1 := 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)
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！