Abstract:
The concept of biomimetics stems from the realization that microbes, plants, and animals have been continuously evolving to cope with environmental and other challenges. Janine Benyus has pointed out that there are two types of biomimetics: forward biomimetics and reverse biomimetics. The earliest recorded attempts at biomimicry relate to manned flight. Percy Shaw's invention of the reflective road studs, more commonly known as 'catseyes', has saved the lives of thousands of road users by lighting the way along roads in the dark. An early commercial product that truly was inspired by nature is the hook and loop fastener i.e. Velcro. The inventor was the Swiss engineer, George de Mestral. He conceived a linear piece of material with hooks that would stick to any rough material. That is, a simple fastener that, unlike a zip fastener or 'hooks and eyes', did not require two surfaces to be lined up precisely.Keywords:
Biomimetics
Fastener
Realization (probability)
Abstract : A Nortec-30 Eddyscan Fastener Hole Inspection Instrument was used to detect known fatigue cracks under the heads of alloy steel fasteners installed in 0.258 in. diameter countersunk fastener holes drilled through 0.330 in. pieces of 7075-T651 aluminum alloy plate. It was found that magnetic fields caused by prior magnetization in a majority of ferrous fasteners resulted in large numbers of false indications. When nonferrous or non magnetized ferrous fasteners were used, the Nortec-30 was able to reliably detect relatively small flaws in the holes underneath the beads of these fasteners. Since the rotating coil eddy current technique is dependent upon the magnetic condition of the fastener, the Nortec-30 is not recommended for use with ferrous fastening systems.
Fastener
Bolted joint
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For a long period of operation, a number of shortcomings have been identified in KPP-5 fastener that is mainly due to an intensive decrease of pressing force of the rail on sleepers. This leads to the appearance of frequent cases of track displacement and fastening elements failure. To verify such hypothesis, the process of power work of KPP-5 fastener during railway track operation was researched. The technique and practical means of controlling the power work of KPP-5 fastener are developed. The influence of various factors of the rail pressing force on the sleeper is determined. The main influence is conditioned by under-rail wear (50.4%). The obtained results made it possible to formulate recommendations for the improvement of KPP-5 fastener where the methodology and practical means of controlling the power work of KPP-5 fastener were proposed. At the same time, it allows increasing the reliability and safety of the rail track during the entire overhaul period.
Fastener
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이 논문에서는 설계정보가 없는 노후 항공기를 사용한 P-3CK 해상초계기 사업을 바탕으로, 끝단거리 부족 결함 수리를 위한 패스너 홀 구조특성 연구를 수행하였다. 이를 위해 끝단거리 결함이 많이 발생했던 낫셀 론저론 부분을 선택하고, 1.5, 1.8, 2.0배 끝단거리에 대한 정적 해석을 수행하여 보수적인 응력을 구하였다. 이 응력을 바탕으로 TWIST의 표준하중 스펙트럼을 적용하여 비행하중을 생성하고, 이 비행하중을 이용하여 균열성장 피로해석을 수행하였다. 이 결과를 통하여 P-3CK 사업 중 수리된 패스너 홀의 유효성을 평가하고 정비주기 및 기준을 설정하였다. In this study, based on P-3CK project using aging aircraft without any design information, the structural assessments of fastener holes to repair the short edge distance defects are investigated. For this purpose, the nacelle longeron which has many defects is selected and then conservative stress is calculated by performing the static analysis of 1.5ED, 1.8ED, 2.0ED defects of longeron fastener holes. This result applies to TWIST standard load spectrum to generate flight load spectrum. Then the crack growth analysis is performed by using flight load spectrum. Through this, the validity of a repaired fastener hole is evaluated. Finally, the standard of repair and the period of maintenance for a defected fastener hole are established.
Fastener
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Fastener
Rivet
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Citations (33)
Abstract This article studies the pull-through resistance of a titanium carbon fibre-epoxy resin laminate fastener. Coupons with fastener holes made with different methods were compared – drilled, milled on a CNC plotter and special fibre application during laminate production. The tests were conducted according to the ASTM D7332 test standard. The studies showed that the fastener hole preparation method impacts the laminate’s resistance to fastener pull-through. Coupons with holes made with standard (drilling and milling) methods showed fastener pull-through resistance higher, on average, by 6.5% than in coupons with holes placed during plate production. Fastener work to rupture was also higher for coupons with milled and drilled holes. Microscopic observations in UV-light, using a fluorescent penetrant, showed differences in failure mechanisms between individual coupons, especially the lack of fibres in the 0° direction, in immediate vicinity to a hole prepared during laminate application.
Fastener
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The effect of different fasteners on fatigue performance for fastener holes was investigated by fatigue tests of simulated fastened structures.The fatigue experimental results of two groups of different fastener specimens were compared and analyzed;fatigue fractured surfaces were observed and analyzed.Based on the equivalent initial flaw size(EIFS) method,the initial fatigue quality was calculated for two groups.The test results show that,fatigue life of rivet fastener hole is longer than that of bolt,but the life scatter of rivet fastener hole is larger than the latter;EIFS for rivet fastener hole is less than for bolt.With different fasteners,the location of crack origin is unchanged and crack initiation life is about 80% of total fatigue life.
Fastener
Rivet
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The inspection and detection of the fastener linked cracks or corrosion is one of the challenging tasks of aircraft maintenance. The goal of the proposed method is to tackle this difficult detection problem; provide a novel approach with enhanced capability of automatic fastener inspection with improved defect detection. There are no pre-knowledge requirements related to the fastener's location, their distribution, nor the need to be centered on the fastener. Based on the reference knowledge of the known defect free fastener sub-image, the method is capable of automatically tracing the fastener's random positions on the blind 2D inspection image, and assessing individual fastener linked quality.
Fastener
Tracing
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Fastener
Interference fit
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Abstract This article first provides an overview of the types of mechanical fasteners. This is followed by sections providing information on fastener quality and counterfeit fasteners, as well as fastener loads. Then, the article discusses common causes of fastener failures, namely environmental effects, manufacturing discrepancies, improper use, or incorrect installation. Next, it describes fastener failure origins and fretting. Types of corrosion in threaded fasteners and their preventive measures are then covered. The performance of fasteners at elevated temperatures is addressed. Further, the article discusses the types of rivet, blind fastener, and pin fastener failures. Finally, it provides information on the mechanism of fastener failures in composites.
Fastener
Rivet
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According to the common four layer structure of subway rail, insulating fastener, track bed and soil, the rail ground model is established by using ANSYS software, and the characteristics of leakage current on insulating fastener are analyzed. The analysis results show that when the loading current is constant, the insulation performance of the insulating fastener directly affects the leakage level of stray current, The lower the insulation performance of the insulating fastener, the greater the current density passing through the insulating fastener, that is, the greater the current leaking from the rail to the track bed and soil. The insulation performance can be improved by 10%-20% by changing the elastic backing plate at the bottom of the insulating fastener into several elastic backing plates with smaller thickness.
Fastener
Leakage (economics)
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