Re: your post
- To: mathgroup at smc.vnet.net
- Subject: [mg15523] Re: your post
- From: Paula Chammas <chammas at dbag.bln.daimlerbenz.com>
- Date: Mon, 18 Jan 1999 23:47:23 -0500
- References: <199901180804.DAA19895@smc.vnet.net.>
- Sender: owner-wri-mathgroup at wolfram.com
Dear All, At the beginning of December I posted a question regarding NDSolve. Thanks for all the responses. I managed to solve the problem using the following: NDSolve[{ w'[t] == -2 w[t] + Tin[t] - Sign[w[t] - v[t]] 2/3 Fn[t], v'[t] == (-v[t] + Sign[w[t] - v[t]] 2/3 Fn[t] )/5, w[0]==0, v[0]==0}, {w,v}, {t, 0, 10}, MaxSteps->40000, AccuracyGoal->2} given Tin[t] := -2 t + 12 /; (5 <= t && t <= 6) Tin[t] := 2 /; (0 <= t && t <=5) Tin[t] := 0 /; (6 <= t && t <= 10) Fn[t] := 0.785 t /; (0 <= t && t <= 2) Fn[t] := 1.57 /; (2 <= t && t <=5) Fn[t] := -0.785 t + 5.495 /; (5 <= t && t <= 7) Fn[t] := 0 /; (7 <= t && t <= 10) Now the system becomes more involved. The new system look like the following: 2 clutches C1 and C2 in parallel w T1,C1 v Tin -------||----- Tout ----m T2,C2 n------ -------||----- Tin is input torque, it is given (see below) and Tin = T1 + T2 w, m are input speeds v,n are ouput speeds So basically we have 2 sets of equations one for C1 and one for C2: w'[t] == -2 w[t] + T1[t] - Sign[w[t] - v[t]] 2/3 Fn[t], v'[t] == ( -v[t]+ Sign[w[t] - v[t]] 2/3 Fn[t] )/5, m'[t] == -2 m[t] + T2[t] - Sign[m[t] - n[t]] Fn[t], n'[t] == ( -n[t] + Sign[m[t] - n[t]] Fn[t] )/5 with the following constraints: Tin[t] = T1[t] + T2[t] w[t] = m[t] v[t] = n[t] v[0] = w[0] = m[0] = n[0] = 0 {t, 0, 10} Fn[t], and Tin[t] are given above. T1 and T2 should be determined by the system When I try to solve the system it does not like the equation Tin[t] = T1[t] + T2[t] I get : Input is not an ordinary differential equation of T1[t] and in some cases NDSolve:: ndsv: Cannot find a starting point of t What is the best way of formulating the problem using mathematica? Any ideas? Thanks in advance and a happy New year to all. Paula _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ Paula Chammas DaimlerChrysler Research and Technology !!NEW Alt-Moabit 96A Tel: +49 30 39982 376 10559 Berlin fax: +49 30 39982 107 paula.chammas at daimlerchrysler.com _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ Experience is a hard teacher because she gives the test first, the lesson afterward.