Adhesion shear strength test method for freshwater/seawater ice on carbon ceramic brake pads of amphibious aircraft

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Y.J. Zhang ◽  
Renzhong Guo ◽  
Yunhui Zhang ◽  
K. Liang

Purpose Based on the mechanical model of typical shear tests, this study aims to propose the test principle and method of freshwater/seawater ice adhesion shear strength of carbon ceramic brake pads for amphibious aircraft, designs and builds the test equipment, prepares the freshwater/seawater ice samples and completes the tests. Design/methodology/approach This study examines the influence of the icing process, mechanism, temperature and freshwater/seawater on ice adhesion shear strength of carbon ceramic brake pads and puts forward a test method for the freshwater/seawater ice adhesion shear strength of amphibious aircraft brake pads. Findings The obtained results examine the influence of the icing process, mechanism, temperature and freshwater/seawater on ice adhesion shear strength of carbon ceramic brake pads. The adhesion shear strength of frozen freshwater and of the seawater of Dalian, Qingdao, Fuzhou and Zhuhai on the surface of aircraft brake pads is measured at –10 to –50°C. It is found that the shear strength of freshwater increases first and then decreases with the decrease of temperature. The adhesion shear strength of seawater; however, increases mainly linear with the decrease of temperature. Originality/value The value of this paper is that the test method proposed and test results for the freshwater/seawater ice adhesion shear strength of amphibious aircraft brake pads provide technical support for the anti-icing design of amphibious aircraft brake devices.

2011 ◽  
Vol 417 (1-3) ◽  
pp. 383-386 ◽  
Author(s):  
Hun-Chea Jung ◽  
Tatsuya Hinoki ◽  
Yutai Katoh ◽  
Akira Kohyama

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Reza Noorzad ◽  
Seyed Taher Ghoreyshi Zarinkolaei

AbstractThis research investigates the behavior of sand reinforced with polypropylene fiber. To do this, 40 direct shear tests and 40 triaxial tests were performed on the coastal beaches of Babolsar, a city in the North of Iran. The effect of parameters such as fiber content, length of fiber and normal or confining pressure on the behavior of Babolsar sand have been studied. In this study, four various fiber contents (0, 0.25, 0.5 and 1 percent), three different lengths of fiber (6, 12 and 18 mm) and four normal or confining pressures (50, 100, 200 and 400 kPa) have been employed. The test results show that fiber inclusion has a significant effect on the behavior of sand. In both direct shear and triaxial tests, the addition of fibers improved shear strength parameters (C, '), increased peak shear strength and axial strain at failure, and also limited the amount of post-peak reduction in shear resistance. The comparison of the test results revealed that due to better fiber orientation toward the direction of principal tensile strain in triaxial test as compared to direct shear tests, the fiber efficiency and its effect on soil behavior is much more significant in triaxial specimens.


2019 ◽  
Vol 32 (2) ◽  
pp. 73-81
Author(s):  
Yun Liu ◽  
Weiyuan Yu ◽  
Xuemin Sun ◽  
Fengfeng Wang

Purpose This paper aims to investigate the effect of ultrasonic vibration (USV) on the evolution of intermetallic compounds (IMCs), grain morphology and shear strength of soldered Ni/Sn/Ni samples. Design/methodology/approach The Ni/Sn/Ni joints were obtained through ultrasonic-assisted soldering. The formation of IMCs, their composition, grain morphology and the fractured-surface microstructures from shear tests were characterized using scanning electron microscopy and energy-dispersive x-ray spectroscopy. Findings Without USV, a planar interfacial Ni3Sn4 layer was formed at the Ni/Sn interface, and a few Ni3Sn4 grains were distributed in the soldered joint. The morphology of these grains was needle-shaped. With USV, several grooves were formed at the interfacial Ni3Sn4 layer due to ultrasonic cavitation. Some deepened grooves led to “neck” connections at the roots of the Ni3Sn4 grains, which accelerated the strong detachment of Ni3Sn4 from the substrate. In addition, two types of Ni3Sn4 grains, needle-shaped and granular-shaped, were observed at the interface. Furthermore, the shear strength increased with longer USV time, which was attributed to the thinning of the interfacial IMC layers and dispersion strengthening from the Ni3Sn4 particles distributed evenly in the joint. Originality/value The novelty of the paper is the detailed study of the effect of USV on the morphology, size changes of interfacial IMC and joint strength. This provides guidance for the application of ultrasonic-assisted soldering in electronics packaging.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guisheng Gan ◽  
Donghua Yang ◽  
Yi-ping Wu ◽  
Xin Liu ◽  
Pengfei Sun ◽  
...  

Purpose The impact strength of solder joint under high strain rate was evaluated by board level test method. However, the impact shear test of single solder bump was more convenient and economical than the board level test method. With the miniaturization of solder joints, solder joints were more prone to failure under thermal shock and more attention has been paid to the impact reliability of solder joint. But Pb-free solder joints may be paid too much attention and Sn-Pb solder joints may be ignored. Design/methodology/approach In this study, thermal shock test between −55°C and 125°C was conducted on Sn-37Pb solder bumps in the BGA package to investigate microstructural evolution and growth mechanism of interfacial intermetallic compounds (IMCs) layer. The effects of thermal shock and ball diameter on the mechanical property and fracture behavior of Sn-37Pb solder bumps were discussed. Findings With the increase of ball size, the same change tendency of shear strength with thermal shock cycles. The shear strength of the solder bumps was the highest after reflow; with the increase of the number of thermal shocks, the shear strength of the solder bumps was decreased. But at the time of 2,000 cycles, the shear strength was increased to the initial strength. Minimum shear strength almost took place at 1,500 cycles in all solder bumps. The differences between maximum shear strength and minimum shear strength were 9.11 MPa and 16.83 MPa, 17.07 MPa and 15.59 MPa in φ0.3 mm and φ0.4 mm, φ0.5 mm and φ0.6 mm, respectively, differences were increased with increasing of ball size. With similar reflow profile, the thickness of IMC decreased as the diameter of the ball increased. The thickness of IMC was 2.42 µm and 2.17 µm, 1.63 µm and 1.77 µm with increasing of the ball size, respectively. Originality/value Pb-free solder was gradually used to replace traditional Sn-Pb solder and has been widely used in industry. Nevertheless, some products inevitably used a mixture of Sn-Pb and Pb-free solder to make the transition from Sn-Pb to Pb-free solder. Therefore, it was very important to understand the reliability of Sn-Pb solder joint and more further research works were also needed.


2013 ◽  
Vol 807-809 ◽  
pp. 1140-1146 ◽  
Author(s):  
Yi Xuan Chen ◽  
Xiu Li Sun ◽  
Zhi Hua Li

The objective of this work is to investigate the stimulation effect of the addition of alkali on the fly ash and slag for stabilizing dredged silt. Based on the test results, a viable alternative for the final disposal of dredged silt as subgrade construction materials were proposed. For this purpose, several mixtures of dredged silt-fly ash-slag and alkali were prepared and stabilized/solidified. In this system, fly ash and slag were used as hardening agents (solidified materials) of dredged silt and alkali was used as activator of fly ash and slag. The shear strength of the mixture was tested by several direct shear tests. Furthermore, X-Ray Diffraction (XRD) analysis was used to determine the hydration products of the system. The specimens were tested in order to determine the shear strength changes versus hydration time and the alkali content. It is indicated that mechanical properties of solidified silt are improved significantly by addition of fly ash and slag stimulated by alkali.


2020 ◽  
Vol 205 ◽  
pp. 04004
Author(s):  
Esra Güneri ◽  
Yeliz Yükselen Aksoy

Depending on increase in the number and type of energy geostructures, studies on the change in soil behavior against heat increase becomes more important. The engineering properties such as permeability, volume deformation of surrounding soils around energy structures mustn’t alter in the presence of heat and thermal cycles. Pumice is a material used in many fields especially for thermal insulation. For that reason, pumice can be used for increasing the resistance of soils in the presence of heat. In this study, the shear strength behavior of sand-bentonite mixtures was investigated with pumice additive under high temperature. In the experiments, 10% and 20% pumice were added to 10% and 20% sand-bentonite mixtures and compaction, direct shear tests were conducted. The direct shear tests were performed both room temperature and under 80°C. The results have shown that the pumice additive increased the shear strength of sand-bentonite mixtures under high temperature when compared the test results under room temperature.


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