An interesting dynamic irradiation-responsive material CaZnGe2O6 : Pb2+ is developed, which shows unique dynamic photoluminescence/photochromism properties under irradiation and advanced anti-counterfeiting applications in dark and bright fields.

Wearable smart light‐emitting devices whose luminescence can respond to human motions have attracted extensive attention. However, the present electroluminescence‐based devices always require power supply and electronic sensors, which makes them inconvenient to use. In this work, the contact electrification induced multicolor mechanoluminescent (ML) Gd3Ga5O12:A (A = Eu3+, Tb3+, Bi3+)/polydimethylsiloxane (PDMS) elastomers are presented. It is revealed that the contact electrification arising from interaction between phosphor and PDMS polymer under mechanics directly excites emission levels, resulting in the self‐recoverable ML not requiring pre‐irradiation and the ultrastrong ML much stronger than that of piezoelectric sulfides. The unique ML mechanism of the elastomers can be understood well according to a proposed electron‐cloud model. Based on the fabric threads processed by the multicolor ML elastomers, some typical wearable smart light‐emitting devices with unique feature of mechanics–photon conversion are designed. It is demonstrated that the devices can emit light sensitively in response to human motions for interactive clothing decoration or dynamic anticounterfeiting, and can quantitatively display real‐time or dynamic stress distributions of body or muscle for human motion monitoring. Therefore, the contact electrification induced multicolor non‐preirradiation ML elastomers are significantly promising for applications in wearable smart light‐emitting devices.

It presents a BaSi2O2N2:Eu2+/PVA persistent luminescence (PersL) gel material that traps can be charged by stress instead of irradiation. It can emit green PersL without preirradiation at room temperature, and even after initial PersL disappears, stored PersL traces can be stimulated again at high temperature. The gel material is demonstrated to be a typical non-Newtonian fluid showing shear thinning characteristics and variable mechanical behaviors. It is viscous at low frequencies, but exhibits elastic behaviors at high frequencies. Typically, the gel material can be made into fixed shapes or pulled into strips. Also, it can be hard enough to bore holes on apples, elastic enough to bounce and even melt. Furthermore, the gel material shows good stability, self-healing, water resistance and biocompatibility. Some typical intelligent light-emitting devices based on the BaSi2O2N2:Eu2+/PVA gel material are designed to show potential applications in safety signage, emergency lighting, anticounterfeiting and tooth occlusion analysis.

This article studies the calculation method for the tooth root bending stress of a high-tooth gear pair with a high contact ratio. The boundary point of the double-tooth meshing zone of the high-tooth gear pair is used as the loading point for the load, and the calculation formula for the bending stress at the dangerous section of the tooth root is obtained. By using ANSYS finite element simulation, the effect of the addendum coefficient, pressure angle, and other gear parameters on the bending stress of the tooth root is studied. The analysis shows that increasing the pressure angle will reduce the bending strength of the tooth root. Increasing the coefficient of a tooth’s top height will lead to an increase in the bending strength of the tooth root. Comparing the finite element analysis (FEA) results with the theoretical calculation results, the analysis shows that under low loads, the maximum error of the theoretical calculation values of the driving toothed gear and driven gear shall not exceed 13.53% and 15.42%, respectively. Under high loads, the maximum theoretical errors of the driving toothed gear and driven gear shall not exceed 8.78% and 10.91%, respectively. This verifies the correctness of the calculation method, which is of great significance for improving the load-bearing capacity of high-tooth gears and for guiding tooth shape design.

Gear transmission systems are widely used in various fields. The occurrence of gear cracks, tooth pitting, and other faults will lead to the dynamic characteristics deterioration of the transmission system. In order to calculate the meshing stiffness of faulty gear pairs more effectively and precisely, this article improves the loaded tooth contact analysis (LTCA) method by analyzing the influence of different fault types on gear deformation, including bending-shearing deformation and contact deformation, which combines the accuracy of the finite element method (FEM) and the rapidity of the analytical method (AM). The improved LTCA method can model the fault areas accurately and optimize the deformation coordination equation under the actual meshing situation of the faulty gear tooth, making it suitable for calculating the meshing stiffness of faulty gears. Based on the calculation results of the finite element method, the accuracy of the improved meshing stiffness calculation method has been verified, and the sensitivity of different fault type parameters on meshing stiffness has been studied.