Patent ID: 7444888

Claim:
Method for determining a contact force vector acting on a rolling element bearing in operation, the rolling element bearing comprising an inner ring, an outer ring and a number of rolling elements between the inner and outer ring, the method comprising: receiving sensor signals from a plurality of sensors measuring performance characteristics of the rolling element bearing; processing the received sensor signals to determine the contact force vector, wherein the plurality of sensors are arranged to measure a bearing component deformation; and the step of processing comprises the step of determining the contact force vector using an inverse transformation of a finite element analysis model which describes the rolling element bearing; the finite element analysis model is simplified using at least one generalised mode shape, the at least one generalised mode shape being a mathematical description of a natural mode deformation of a component of the rolling element bearing, such as the inner or outer ring; and the simplified model has the form: (1) s _ ⁡ ( ω ) = T = m ⁢ K = p - 1 ⁡ ( ∂ F ⁡ ( θ _ , α _ ) ∂ p _ ⁢ f _ c ⁡ ( ω ) + f _ e ⁡ ( ω ) ) in which (2) s(ω) is a set of measurement points where the deformations are measured at a frequency ω; (3) T m is a subset of a transformation matrix (4) T used for the calculation of a stiffness matrix K P for the simplified model, the stiffness matrix K P =TK FEM T, K FEM being a stiffness matrix of a finite element analysis model of the component; p is the vector describing the deformation of the component; θ is the co-ordinate in circumferential direction of the component; α is the co-ordinate perpendicular to the component; F is a set of shape functions as used for the simplified modeling of the component; f c is a vector comprising the contact forces working in points with co-ordinates stored in the vectors O and α; and f e is a vector comprising other forces acting on the component, and the step of determining the contact force vector f comprises the step of solving the simplified model equations for f c , O and α and summing the contact forces according to f=f(f c ,O,α).