Abstract: A method to introduce a deliberate mismatch into a turbomachine bladed wheel so as to reduce vibration amplitudes of the wheel in forced response. The method includes a step of determining an optimum value of the standard deviation for the mismatch as a function of operating conditions of the wheel inside the turbomachine, with respect to the maximum vibration amplitude response required on the wheel. The method further includes a step of at least partly placing blades with different natural frequencies on the wheel such that the standard deviation of the frequency distribution of all blades is equal to at least the mismatch value, the mismatch value being determined statistically.

Abstract: Method to introduce a deliberate mismatch into a turbomachine bladed wheel so as to reduce vibration amplitudes of the wheel in forced response, characterised by the fact that it consists of determining an optimum value of the standard deviation for the mismatch as a function of operating conditions of the wheel inside the turbomachine, with respect to the maximum vibration amplitude response required on the wheel, and of at least partly placing blades with different natural frequencies on the said wheel such that the standard deviation of the frequency distribution of all blades is equal to at least the said mismatch value, the said mismatch value being determined statistically.

Abstract: A two-part fastener for mounting a component upon a substrate comprises a first part having an elongate hollow body, a self-tapping threaded portion defined upon an exterior peripheral portion of the elongate body whereby the first part can be threadedly secured within the substrate, and a first snap-fitting engagement member defined upon an internal peripheral portion of the first part. The second part likewise comprises an elongate body, a support portion for fixedly mounting the component thereon, and a plurality of axially spaced second snap-fitting engagement members defined upon an external peripheral portion of the second part. When the second part is axially inserted into the first part, for example, with the component affixed thereon, the second snap-fitting engagement members of the second part selectively engage the engagement member of the first part such that the disposition of the component supported upon the second part can be adjustably mounted as desired relative to the substrate.