A biomimetic vibration sensor to sense external vibrations was designed based on the hair receptor of insects similar to the water strider. Platinum core piezoelectric ceramic fiber body was prepared by squeeze and press method. This was followed by high-temperature sintering, surface electrode coating, and polarizing to fabricate the symmetric coated metal core piezoelectric fiber vibration sensor. A cantilever beam structure with two surface electrodes was designed as the theoretical sensor model. The fiber was fixed on a matrix structure. Experiments were performed to verify sensing characteristics under impact vibration and simple harmonic excitation. Results showed that the symmetric coated metal core piezoelectric fiber was able to sense amplitude and direction of impact vibration along with frequency, amplitude, and direction under simple harmonic excitation. Such a biomimetic vibration sensor can be effectively used to sense vibration amplitude and direction for a wide range of applications.

Growing interest is being attracted by stretchable and flexible electronics recently due to their attractive characteristics, commercial potentials, and engineering challenges. In comparison with the system on a macroscopic scale, different failure modes are observed in a system with a thin film bonded on an elastomeric substrate. Furthermore, the experimental observations reveal that failure modes occur in turn with the increasing of thickness ratio of the film to substrate. In this paper, theoretical analysis is performed on the failure mechanism in this system with the focus on transitions among these failure modes based on the theory of fracture mechanics. The present theoretical predictions are coincident with related experiment results and can be used to guide the related structural design.

Prediction accuracy is a key problem in estimating the fatigue resistance of engineering structures. Here, we consider mechanical structures with fasteners that are simultaneously subjected to a combination of shear and tension (or compression) loads. The currently used detail fatigue rating method is modified and an extended detail fatigue rating method is proposed to improve the estimation results. This is achieved by considering the effect of the load, stress concentration, and fatigue failure criterion on the fatigue capacity. An experimental assessment is also made of many specimens with different structures. A comparison of the estimation results obtained using the extended detail fatigue rating method and the experimental results shows that the new method gives results that are acceptable in engineering practice.

The stretchable and flexible electronics with the structure of inorganic films on plastic substrate has recently attracted an increasing interest. Interfacial failure inevitably occurs when the structure is subject to repeated bending or stretching in application. An analysis is presented in this letter on the slipping failure mechanism for the interface between inorganic film and plastic substrate. The critical radius of system curvature for the slipping crack propagation on its interface is obtained to analyze the bendability of the structure, which can provide the design guideline and characterization method to determine the interface fracture toughness of slipping failure.