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The technology of combining a negative Poisson's ratio (NPR) anchor cable with a double-layer truss support technology (N-DTST) is a new support technology for deeply buried tunnels. To evaluate the stability of the surrounding rock support after the application of this new support technology in the Sichuan–Tibet Railway tunnels, geomechanical model tests were conducted for the first time. A model test loading system with intelligent numerical control and automated analysis was developed to reveal the changing patterns of displacement and stress in the surrounding rock of tunnels. The test results revealed the following: (1) After the burial depth exceeds 800 m, the tunnel undergoes large deformations with displacements greater than 37.5 mm, and the traditional anchor cable support fails; (2) In the burial depth range of 800–2,000 m, the new support technology can control the surrounding rock deformation, and the surrounding rock displacement is less than 10 mm; (3) After the tunnel excavation, the radial stress decreases and the tangential stress concentrates. When the burial depth is greater than 800 m, the radial stress compensation provided by the anchor cable no longer meets the stability of the tunnel surrounding rock, and the new support technology can provide high stress to support the deeply buried tunnel; (4) After the burial depth exceeds 2,000 m, butterfly-shaped damage occurs on the tunnel surface, the truss structure inside the tunnel is damaged, and the support structure fails, so it is recommended to carry out reinforcement support at the arch shoulder. The research results verify the effectiveness of the new support technology and provide an important reference for the support of the surrounding rock in deeply buried tunnels. Practical Applications: Common Poisson's ratio anchors/ropes or shotcrete are widely used in tunnels as the core support structure. They often fail to meet the requirements of fractured rock, expansive rock, and high-ground-stress soft rock tunnels because they cannot adapt to the large deformation characteristics of the catastrophic rock mass. Based on this, this paper proposed a new support technology: an anchor rod/rope with a negative Poisson's ratio material combined with a double-layer three-dimensional truss for joint support of the tunnel. To verify the feasibility of this technology, the research and development team developed a new design for the structure. To verify the feasibility of this technology, a large-scale geomechanical model test system was developed, and a comparative model test was conducted using this test system in combination with the ground stress environment of the Sichuan–Tibet Railway to verify the effectiveness of the new support technology proposed in this paper, which provides a reference for the world's deep buried tunnel support technology. [ABSTRACT FROM AUTHOR]

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Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The weight of polymer gears is increasing continuously due to their advantageous properties. This is the reason why in recent years traditional metal gears have been replaced by polymer counterparts in plethora applications. Despite their benefits, their load-carrying capacity is limited. The polymer gears become unable to operate and their teeth generally fail when the load exceeds a defined limit. It is required to explore the limit of polymer materials in gear field. In this work, the gears are manufactured by machine cutting. This paper aims to investigate the limit of load-carrying capacity and the lifetime of POM and PA6 G gears.

In view of the problem that the general electronic instrument and equipment used for transient parameters testing can not work normally under the influence of strong electromagnetic interference, an overload testing device which can effectively shield the strong electromagnetic interference is designed. The shell structure of the testing device is made of multilayer metal materials with good electromagnetic shielding performance, and the internal structure is filled with polyurethane filling technology. The internal circuit system combines low-power design and data acquisition and storage technology to complete the acquisition and recording of overload parameters during the whole flight process. In the actual firing test of electromagnetic railgun, the test device reliably recorded the overload data of the projectile. The result of the experiment shows that the shell structure of the test device has effective electromagnetic shielding for strong electromagnetic fields，and the internal circuit system has successfully acquired the transient overload parameters of the projectile.

The overload test is the most severe a drilling mast or a service rig mast can be submitted to before putting into operation. In accordance with the actual standard for masts and derricks API 4F, the verification of the mast's behaviour for such a load is not always mandatory for manufacturers, but, usually, purchasers require it, in order to increase the confidence in their product and to be sure that the mast will respond appropriately to all requests during its work at the borehole. The value of this load is established by the purchaser in accordance with API 4F requirements, taking into account the real conditions in which the mast will work: borehole's deep, geological or environmental conditions, earthquakes etc. In the present paper there are analysed the results obtained using ANSYS program for a mast of 320 kN submitted to an overload which exceeds with 50% the maximum static hook load. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la ALAD is the property of Publicidad Permanyer SLU and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)