Introduction

The dynamic vibration analysis of mechanical structures requires a load to be applied on a small area alongside a single force component. To achieve this accurately, an innovative, structurally simple and inexpensive stinger is proposed, which filters and significantly reduces unwanted load components by introducing points of contact at both sides of the stinger, ensuring a double hinge configuration.

Technical features

The substantial difference of the proposed stinger, compared to the classical design, consists in the filtering of the unwanted spurious load components by the introduction of additional degrees of freedom, instead of relying on the stiffness difference along the various directions. This occurs through the use of a stinger that provides point contact at both ends, and whose positioning is guaranteed by a compression pre-load. The contact point determines the constraint of the system for the double hinge stinger (instead of double interlocking as in the classic case), which therefore entails the possibility of transmitting only the force along the stinger axis. Two solutions are proposed for this stinger concept: the Ball Stinger (with a sphere mating a disc with a spherical concave seat), and the Strut Stinger (featuring conical spikes at both ends in contact with conical concave seats).

The ability to filter out unwanted loads is greater than that of state-of-the-art stingers. The higher axial stiffness allows higher maximum test frequencies to be used; the axial stiffness of the connection freed from the transverse/bending connection allows greater flexibility in design. Furthermore, due to its simplicity, the device has low construction costs.

Possible Applications

• Engineering field;
• Analysis of dynamic behavior in response to vibration;
• Structural analysis to analyze the dynamic behavior in response to vibrations;
• Experimental modal analysis;​
• Experimental harmonic response analysis;​
• Dynamic tests using shaker.

Advantages

• Greater transversal and flexural compliance (double hinge constraint);​
• Greater axial stiffness, therefore higher maximum test frequencies;​
• Axial stiffness decoupled from both the transversal and flexural stiffnesses;​
• Design and manufacturing simplicity with lower costs.