Experimental and numerical studies on a new type of bolt-ball joint for spatial grid structures

2022 ◽  
Vol 188 ◽  
pp. 107035
Author(s):  
Dabin Yang ◽  
Mingjin Li ◽  
Feng Fu ◽  
Jinzhi Wu
2018 ◽  
Vol 38 (2) ◽  
pp. 242-252
Author(s):  
Jianrong Yang ◽  
Zhiyu Zhang

A new concept of a flexible rock-shed is presented for protection of the railway from falling rocks. The flexible rock-shed is made of flexible nets connected by specific spring spacer bars to an array of reinforced concrete portable frames which are linked by a longitudinal steel tube truss. To evaluate the performance of the flexible rock-shed, experimental and numerical studies are carried out in the present study. Impact tests are conducted on a full-scale partial model of the prototype structure when it is subjected to a falling block of 340 kg. The impact time interval, maximum deflection of the flexible net, tensile forces in the supporting ropes, and axial strains of spring spacer bars are recorded. To further examine the dynamic behavior of the flexible rock-shed, numerical simulations are also carried out by using the explicit finite element code ANSYS/LS-DYNA. It is found that the numerical results coincide well with the experimental data and both the numerical and experimental studies reveal that the structure can withstand impact energy of 50 kJ with all the materials working in the elastic range. The structural details are improved and the basis for the design and construction of similar structures in the future is provided.<br>


2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Jianwen Zhong ◽  
Enzhi Wang ◽  
Yuande Zhou ◽  
Qingbin Li ◽  
Penghui Li

This paper presents a retrospective investigation into the performance of a new type of flexible-arch configurations in Shimenzi arch dam based on the past ten-year-long field measurements. The flexible-arch configurations are mainly comprised of artificial short joints at the middle downstream surface and a middle contraction joint with hinged well and enlarged arch ends with bending joints. Fundamental design considerations of these components are provided, and their contributions to the performance of Shimenzi arch dam are discussed in detail using the monitoring data from joint meters, strain gauges, and thermometers. Some elementary numerical studies have been conducted on a typical arch structure with different arrangements of artificial joints. Both the field data and numerical results prove well the effectiveness of the purposely built short joints and the middle contraction joint on the relaxation of tensile stress mobilization. Field survey data also clearly demonstrate the significance of the hinged well at the upstream side of the middle joint for a continuous arch force transfer.


2018 ◽  
Vol 12 (3) ◽  
pp. 405-412
Author(s):  
Toshihiro Yukawa ◽  
Jun Sasaki ◽  
◽  

A new type of surgical instrument developed as substitutes for an abdominal retractor for use during surgery is described. The new instrument can increase the efficiency of retraction during surgery. We develop an assistant mechanism which has a six-D.o.F, as high controllability at the tip of the mechanism. The mechanism consists of a serial three-link manipulator whose each joint is composed of a ball joint. The instrument needs to maintain the shape of the relevant body part while maintaining own posture during surgery.


2010 ◽  
Vol 38 (9) ◽  
pp. 2428-2433 ◽  
Author(s):  
Wenyuan Yang ◽  
Zhiwei Dong ◽  
Ye Dong

2001 ◽  
Vol 123 (2) ◽  
pp. 265-271 ◽  
Author(s):  
Fengfeng Xi ◽  
Rosario Sinatra ◽  
Wanzhi Han

In this paper the effect of leg inertia on hexapod dynamics is investigated. Hexapods under investigation are a new type that is made of sliding legs with constant lengths. A complete dynamic model of sliding-leg hexapods is developed including leg inertia. Based on this dynamic model, the effect of leg inertia on hexapod dynamics is investigated in terms of two parameters. The first parameter is the ratio of the total leg mass to the mass of the moving platform, and the second parameter is the acceleration of the moving platform. Numerical studies reveal that the effect of leg inertia may be negligible at low speeds, but becomes significant at high speeds. Hence, leg inertia must be included for modeling hexapod dynamics for high-speed applications.


2015 ◽  
Vol 32 (1) ◽  
pp. 86-101
Author(s):  
Ramy Harik ◽  
Alipio Nicolas ◽  
Mohamed Dassouki ◽  
Alain Bernard

Purpose – Biomimetic study existing natural biological elements to produce engineering products with similar performance and abilities. The purpose of this paper is to highlight biomimetic studies to produce a new type of airplanes: adding remiges, bending ability and flapping mechanisms. Design/methodology/approach – The used methodology was to thoroughly investigate the literature, to define the proper endurance and fatigue parameters, to perform a series of numerical studies and report improvement percentages relevant to defined parameters. Findings – By adding remiges and the bending mechanism, the authors managed to reach – numerically – the preset desired structure goal. Efficiency increased using remiges with less drag force. In addition, with the help of the bending wing technique, the drag force was improved. The flapping mechanism showed high vibration rates. Last but not least, applying multiple winglets gave a better optimization of the endurance parameter. Research limitations/implications – Research is conducted at a university without any research facilities. No laboratories exist, and acquiring research papers is mostly difficult and costly. Originality/value – The research study is original in the sense of its numerical investigation. Proposing biomimetic was at the heart of the airplane invention and cannot be stated as an original contribution. Rather the field has been recently abandoned, and performing this major literature review can be considered as original in a sense it summarizes recent to somewhat old advancement.


Author(s):  
Lucien F. Trueb

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.


Author(s):  
T. Ichinokawa ◽  
H. Maeda

I. IntroductionThermionic electron gun with the Wehnelt grid is popularly used in the electron microscopy and electron beam micro-fabrication. It is well known that this gun could get the ideal brightness caluculated from the Lengumier and Richardson equations under the optimum condition. However, the design and ajustment to the optimum condition is not so easy. The gun has following properties with respect to the Wehnelt bias; (1) The maximum brightness is got only in the optimum bias. (2) In the larger bias than the optimum, the brightness decreases with increasing the bias voltage on account of the space charge effect. (3) In the smaller bias than the optimum, the brightness decreases with bias voltage on account of spreading of the cross over spot due to the aberrations of the electrostatic immersion lens.In the present experiment, a new type electron gun with the electrostatic and electromagnetic lens is designed, and its properties are examined experimentally.


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