Publications

Abstract not provided.

Abstract not provided.

Abstract not provided.

This paper discusses issues that arise in controlling high quality mechanical shock inputs for mock hardware in order to validate a model of a bolted connection. The dynamic response of some mechanical components is strongly dependent upon the behavior of their bolted connections. The bolted connections often provide the only structural load paths into the component and can be highly nonlinear. Accurate analytical modeling of bolted connections is critical to the prediction of component response to dynamic loadings. In particular, it is necessary to understand and correctly model the stiffness of the joint and the energy dissipation (damping) that is a nonlinear function of the forces acting on the joint. Frequency-rich shock inputs composed of several decayed sinusoid components were designed as model validation tests and applied to a test item using an electrodynamic shaker. The test item was designed to isolate the behavior of the joint of interest and responses were dependent on the properties of the joints. The nonlinear stiffness and damping properties of the test item under study presented a challenge in isolating behavior of t4he test hardware from the stiffness, damping and boundary conditions of the shaker. Techniques that yield data to provide a sound basis for model validation comparisons of the bolted joint model are described.

The dynamic response of critical aerospace components is often strongly dependent upon the dynamic behavior of bolted connections that attach the component to the surrounding structure. These bolted connections often provide the only structural load paths to the component. The bolted joint investigated in this report is an inclined lap-type joint with the interface inclined with respect to the line of action of the force acting on the joint. The accurate analytical modeling of these bolted connections is critical to the prediction of the response of the component to normal and high-level shock environmental loadings. In particular, it is necessary to understand and correctly model the energy dissipation (damping) of the bolted joint that is a nonlinear function of the forces acting on the joint. Experiments were designed and performed to isolate the dynamics of a single bolted connection of the component. Steady state sinusoidal and transient experiments were used to derive energy dissipation curves as a function of input force. Multiple assemblies of the bolted connection were also observed to evaluate the variability of the energy dissipation of the connection. These experiments provide insight into the complex behavior of this bolted joint to assist in the postulation and development of reduced order joint models to capture the important physics of the joint including stiffness and damping. The experiments are described and results presented that provide a basis for candidate joint model calibration and comparison.