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h i g h l i g h t sA novel development of a hybrid vacuum/triple glazing system with a pressure equalisation design is reported. Negative pressure test was undertaken to examine the stresses and deformation generated in the new system. The maximum stresses and deflections were significantly reduced compared to the conventional design. This novel glazing system is safer than conventional vacuum glazing units. a b s t r a c tVacuum glazing units (VGUs) are thought to be a type of glazing system with superior effective insulation performance. However, the differential pressure between the outside and the inner spaces and the supporting pillars create a high pre-existing stress field in the constituent glass during fabrication and hence make the units highly susceptible to breakage, even under small applied loads. In order to address this problem, a novel hybrid vacuum/triple glazing system with a pressure equalisation design has been devised and is reported in this paper. In this system, a VGU is enclosed by two glass panels to form a triple glazing unit system. This new design creates an equalised air pressure on both sides of the VGU hence subjects the VGU to no additional loads apart from the inherent fabrication stresses. This results in a high thermal and sound insulation as well as a more durable safety performance of the hybrid glazing component. Pressure tests were undertaken on the novel glazing system to confirm its reliability. Results show that under various loading levels, the stresses and deflections in the VGU of this novel glazing system always remain at a marginal level, and hence the likelihood of breakage for VGUs can be reduced significantly.

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PurposeThis paper aims to analyze the bearing characteristics of the high speed train window glass under aerodynamic load effects.Design/methodology/approachIn order to obtain the dynamic strain response of passenger compartment window glass during high-speed train crossing the tunnel, taking the passenger compartment window glass of the CRH3 high speed train on Wuhan–Guangzhou High Speed Railway as the research object, this study tests the strain dynamic response and maximum principal stress of the high speed train passing through the tunnel entrance and exit, the tunnel and tunnel groups as well as trains meeting in the tunnel at an average speed of 300 km·h-1.FindingsThe results show that while crossing the tunnel, the passenger compartment window glass of high speed train is subjected to the alternating action of positive and negative air pressures, which shows the typical mechanic characteristics of the alternating fatigue stress of positive-negative transient strain. The maximum principal stress of passenger compartment window glass for high speed train caused by tunnel aerodynamic effects does not exceed 5 MPa, and the maximum value occurs at the corresponding time of crossing the tunnel groups. The high speed train window glass bears medium and low strain rates under the action of tunnel aerodynamic effects, while the maximum strain rate occurs at the meeting moment when the window glass meets the train head approaching from the opposite side in the tunnel. The shear modulus of laminated glass PVB film that makes up high speed train window glass is sensitive to the temperature and action time. The dynamically equivalent thickness and stiffness of the laminated glass and the dynamic bearing capacity of the window glass decrease with the increase of the action time under tunnel aerodynamic pressure. Thus, the influence of the loading action time and fatigue under tunnel aerodynamic effects on the glass strength should be considered in the design for the bearing performance of high speed train window glass.Originality/valueThe research results provide data support for the analysis of mechanical characteristics, damage mechanism, strength design and structural optimization of high speed train glass.