I have a function axialforce[a,b,c] and a function momentY[a,b,c].
I want to see the line in 3d (a,b,c) space where axialforce[a,b,c]==-0.5 AND momentY[a,b,c]==0.
I tried both
ContourPlot3D[Ms[a, b, c] == 0 && Ns[a, b, c] == -0.5, {a, -200, 200}, {b, -200, 200}, {c, -50, 50}]
ContourPlot3D[Ms[a, b, c]^2+(Ns[a, b, c] + 0.5)^2 == 0, {a, -200, 200}, {b, -200, 200}, {c, -50, 50}]
without any output on screen (A silent NOTHING). Am I do something wrong?
The complete code is following:
ClearAll["Global`*"]
ε[y_,z_,a_,b_,c_]:=-a y+b z+c
σ[ε_]:=\[Piecewise] 0 ε<-εu\[Or]εu<ε
-fy -εu<=ε<-εy
fy/εy ε -εy<=ε<=εy
fy εy<ε<=εu
MRd[a_,b_,c_]:=-\!\(
\*SubsuperscriptBox[\(\[Integral]\), \(\(-1\)/4\), \(1/4\)]\(
\*SubsuperscriptBox[\(\[Integral]\), \(\(-1\)/4\), \(1/4\)]y\ σ[ε[y, z, a, b, c]] \[DifferentialD]y \[DifferentialD]z\)\)
Ms[a_,b_,c_]:=-\!\(
\*SubsuperscriptBox[\(\[Integral]\), \(\(-1\)/4\), \(1/4\)]\(
\*SubsuperscriptBox[\(\[Integral]\), \(\(-1\)/4\), \(1/4\)]z\ σ[ε[y, z, a, b, c]] \[DifferentialD]y \[DifferentialD]z\)\)
Ns[a_,b_,c_]:=-\!\(
\*SubsuperscriptBox[\(\[Integral]\), \(\(-1\)/4\), \(1/4\)]\(
\*SubsuperscriptBox[\(\[Integral]\), \(\(-1\)/4\), \(1/4\)]σ[ε[y, z, a, b, c]] \[DifferentialD]y \[DifferentialD]z\)\)
εy=2;fy=235;εu=20;
ContourPlot3D[Ms[a,b,c]==0\[And]Ns[a,b,c]==-0.5,{a,-200,200},{b,-200,200},{c,-50,50}]
```
