Add tests

test/friction_model_tests.f90

@@ -134,5 +134,85 @@ function test_maxwell() result(rst)
     end if
 end function
 
+! ------------------------------------------------------------------------------
+function test_gmsm() result(rst)
+    ! Arguments
+    logical :: rst
+
+    ! Local Variables
+    logical :: check
+    integer(int32) :: i, j
+    type(generalized_maxwell_slip_model) :: mdl
+    real(real64) :: f, nrm, c, x, v, muc, mus, bv, s0, alpha, vs
+    real(real64) :: dzdt(3), z(3), f_ans, g, a1, a2, s
+    real(real64) :: args(9)
+
+    ! Initialization
+    rst = .true.
+    call mdl%initialize(3)
+    call random_number(nrm)
+    call random_number(c)
+    call random_number(x)
+    call random_number(v)
+    call random_number(muc)
+    call random_number(mus)
+    call random_number(bv)
+    call random_number(s0)
+    call random_number(alpha)
+    call random_number(vs)
+    call random_number(args)
+    call random_number(z)
+
+    ! Ensure sum(vi) = 1
+    args(3) = 1.0d0 - (args(6) + args(9))
+
+    ! Define the model
+    j = 0
+    do i = 1, size(args), 3
+        j = j + 1
+        check = mdl%set_element_stiffness(j, args(i))
+        check = mdl%set_element_damping(j, args(i+1))
+        check = mdl%set_element_scaling(j, args(i+2))
+    end do
+    mdl%attraction_coefficient = c
+    mdl%coulomb_coefficient = muc
+    mdl%shape_parameter = alpha
+    mdl%static_coefficient = mus
+    mdl%stiffness = s0
+    mdl%stribeck_velocity = vs
+    mdl%viscous_damping = bv
+
+    ! Compute the solution
+    a1 = mdl%coulomb_coefficient * nrm / mdl%stiffness
+    a2 = nrm * (mdl%static_coefficient - mdl%coulomb_coefficient) / &
+        mdl%stiffness
+    s = abs(v) / mdl%stribeck_velocity
+    g = a1 + a2 / (1.0d0 + s**mdl%shape_parameter)
+    f_ans = 0.0d0
+    do i = 1, 3
+        if (abs(z(i)) < g) then
+            dzdt(i) = v
+        else
+            dzdt(i) = sign(1.0d0, v) * mdl%get_element_scaling(i) * &
+                mdl%attraction_coefficient * &
+                (1.0d0 - z(i) / (mdl%get_element_scaling(i) * g))
+        end if
+        f_ans = f_ans + mdl%get_element_stiffness(i) * z(i) + &
+            mdl%get_element_damping(i) * dzdt(i)
+    end do
+    f_ans = f_ans + mdl%viscous_damping * v
+
+    ! Test
+    f = mdl%evaluate(0.0d0, x, v, nrm, z)
+    if (.not.assert(f, f_ans))  then
+        rst = .false.
+        print *, "TEST FAILED: test_gmsm -1"
+    end if
+    if (.not.mdl%has_internal_state()) then
+        rst = .false.
+        print *, "TEST FAILED: test_gmsm -2"
+    end if
+end function
+
 ! ------------------------------------------------------------------------------
 end module

test/friction_test.f90

@@ -18,6 +18,9 @@ program test
 
     check = test_maxwell()
     if (.not.check) flag = 3
+
+    check = test_gmsm()
+    if (.not.check) flag = 4
 
     ! End
     stop flag