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The crystal oscillator is a widely used electronic component in a circuit, whose accuracy is strongly affected by the external mechanical environment. To depict the failure mechanism of the crystal oscillator, the damage boundary of this component under the shock environment is studied experimentally in this paper. Through subjecting “step-up” loads on different groups of crystal oscillators, two failure modes (frequency jumping and structural fracture) are monitored and validated. Experimental results prove that “frequency jumping” failure mode is governed by the value of the acceleration shock response spectrum (ASRS) in a certain frequency range, while the failure mode “structural fracture” is governed by the peak value of the ASRS. Through analyzing the shock response spectrum, damage boundaries are given for these two failure modes, which can provide a reference for component design and failure assessment.

The offshore structures experience severe shock environment caused by storms, episodic waves, icebergs or supply ships. The aerospace equipment may also encounter severe shock loadings due to pyrotechnic shock. The intensive shock causes structural failures, or even results in fatal consequences on the related facilities and persons. Therefore it is important to study the response and the damage behavior of structures under shock loading. The damage boundary of a beam under shock is studied, based on the structural dynamics and the shock response spectrum analysis. The relationship between the critical real velocity and the critical pseudo velocity is investigated, and the concept of loading factor is proposed. A simple and practical rule of estimating structure fragility is developed based on the pseudo velocity shock response spectrum and the loading factor. The explicit numerical simulation of a beam under shock loading is carried out using LS-DYNA. The critical shock response spectrums as well as the loading factor of the beam is obtained. This paper has an important significance of helping structural engineers to design the offshore and aerospace equipment under shock environment.

Abstract. Using the mixture of nanoporous materials and its associated lyophobic fluid for damping application is a novel technology called colloidal damper. Compression caused liquid intrusion transfers the mechanical energy into interface energy and so that producing damping effect and colloidal damper has great potential as shock absorber. In this paper, a colloidal damper consist water and hydrophobic silica gel particles as working medium is investigated. The working mechanism of colloidal is first introduced. Then, an experiment is conducted to investigate the mechanical properties of colloidal damper. Finally, the energy dissipation performance is analyzed.