The effects of edge quality on the measured compression strength of quasi-isoptropic composite specimens and its practical implication to the development of allowables

2020 ◽  
pp. 002199832096080
Author(s):  
Alan T Nettles ◽  
William E Guin ◽  
James P Mavo
Keyword(s):  
Compression Strength ◽  
Practical Implication ◽  
Pull Out ◽  
Compression After Impact ◽  
Starting Point ◽  
Open Hole ◽  
Edge Quality ◽  
Microscopic Damage ◽  
Isotropic Carbon

This manuscript presents results from an experimental study that examined the effect of quality of edge finish of test coupons on the measured compression strength of quasi-isotropic carbon fiber laminates using test standard ASTM D6641. Different cutting and grinding tools were used to machine specimens to get them within the required dimensional tolerances, all of which caused microscopic damage to the specimen edge, mainly in the form of fiber pull-out. Results of compression strength testing showed that the fiber pull-out, despite being only on the order of 0.008 mm in depth, caused a significant reduction in measured compression strength. Upon polishing of the specimen edges to remove the microscopic “gouges” of fiber pull-out, the measured compression strength of the specimens increased. It was also found that open hole compression (OHC) and compression after impact (CAI) strength test results were not affected by fiber pull-out on the edges of specimens. The implications of these results on the development of pristine strength allowables is discussed and a more practical starting point at which to develop allowables is presented.

Polyimide Composites from ‘Salt-Like’ Solution Precursors

2001 ◽  
Vol 13 (4) ◽  
pp. 235-250 ◽  
Author(s):  
Roberto J Cano ◽  
Tan H Hou ◽  
Erik S Weiser ◽  
Terry L St Clair
Keyword(s):  
Mechanical Properties ◽  
Carbon Fibre ◽  
Compression Strength ◽  
Elevated Temperatures ◽  
Flexural Modulus ◽  
Matrix Composites ◽  
Compression After Impact ◽  
Open Hole ◽  
Polyimide Composites ◽  
Polyimide Matrix

Four NASA Langley-developed polyimide matrix resins, LaRC™-IA, LaRC™-IAX, LaRC™-8515 and LaRC™-PETI-5, were produced via a ‘salt-like’ process developed by Unitika Ltd. The salt-like solutions (65% solids in NMP) were prepregged onto Hexcel IM7 carbon fibre using the NASA LaRC™ multipurpose tape machine. Process parameters were determined and composite panels fabricated. The temperature dependent volatile depletion rates, the thermal crystallization behaviour and the resin rheology were characterized. Composite moulding cycles were developed which consistently yielded well consolidated, void-free laminated parts. Composite mechanical properties such as the short beam shear strength; the longitudinal and transverse flexural strength and flexural modulus; the longitudinal compression strength and modulus; and the open hole compression strength and compression after impact strength were measured at room temperature and elevated temperatures. The processing characteristics and the composite mechanical properties of the four intermediate modulus carbon fibre/polyimide matrix composites were compared to existing data on the same polyimide resin systems and IM7 carbon fibre manufactured via poly(amide acid) solutions (30–35% solids in NMP). This work studies the effects of varying the synthetic route on the processing and mechanical properties of the polyimide composites.

Correlation of Cutting Force and Power Consumption for Ultrasonic-Vibration-Assisted Cutting of Label Paper Stacks

2012 ◽  
Author(s):  
Karl-Robert Deibel ◽  
Jens Boos ◽  
Sascha Weikert ◽  
Konrad Wegener
Keyword(s):  
Cutting Force ◽  
Ultrasonic Vibration ◽  
Quality Parameters ◽  
Cutting Edge ◽  
Pull Out ◽  
Edge Quality ◽  
Force Reduction ◽  
Cutting Speeds ◽  
Guillotine Cutting

Experiments comparing conventional and ultrasonic vibration assisted guillotine cutting of paper stacks have been performed on plain and aluminum coated label paper. It is shown that ultrasonic vibration assisted cutting reduces the cutting force for both paper species. Reduction of the cutting force allows the down holder force to be decreased and lowers the compression of the paper stack necessary to prevent pull-out of the top sheets of paper. Using a higher amplitude setting on the ultrasonic generator further decreases the cutting force for the paper stack. For three different cutting speeds, it is shown that ultrasonic vibration assisted cutting force reduction depends on the average speed of the tool for both paper species. A linear regression with present experimental data is done to obtain an equation for the relation between input generator power and resulting cutting force. Finally, the quality of the cutting edge is examined, quality parameters are defined, and according to these the cutting edge quality is assessed.

Application of membrane technology in the pretreatment of cheese dairies wastes and co-treatment in a municipal conventional biological unit

1997 ◽  
Vol 36 (2-3) ◽  
pp. 361-367 ◽  
Author(s):  
Eleftheria Papachristou ◽  
Costas T. Lafazanis
Keyword(s):  
Cheese Whey ◽  
Treatment Plant ◽  
Membrane Technology ◽  
Biological Unit ◽  
Urban Sewage ◽  
Dairy Wastes ◽  
Starting Point ◽  
Quality Of Milk ◽  
Cheese Production

A great number of cheese dairies and dairy industries in Greece are disposing their wastes, mainly cheese whey, either on land or in surface receivers, in large quantities creating a major environmental problem. A typical agricultural and pastoral provincial town of 70,000 inhabitants, Trikala, became the starting point of this research. A co-treatment of the urban sewage and the dairy wastes in the municipal treatment plant was recommended. The successful application of the above statement is based primarily on the pretreatment of the cheese dairies wastes. So far for cheese whey the recovery of the lactose serum in the contemporary central unit applying membrane technology has been suggested. As far as the wastewaters of the washing and refrigeration are concerned a pretreatment is required for the defatting in a grease trap, the grating, the adjustment of pH and the equalisation in an appropriate tank. Finally, this research has also focussed on the importance of membrane technology in improving the quality of milk and cheese production.

PENERAPAN PEMBELAJARAN METODE DISKUSI UNTUK MENINGKATKAN AKTIVITAS BELAJAR SISWA PADA PEMBELAJARAN IPS TERPADU DI KELAS VIII.B SMP NEGERI 5 KOTA SOLOK

2019 ◽  
Vol 5 (1) ◽  
pp. 35-42
Author(s):  
Erma Yenis
Keyword(s):  
Student Learning ◽  
Learning Outcomes ◽  
Learning Process ◽  
Teaching And Learning ◽  
Student Learning Outcomes ◽  
Learning Activities ◽  
Good Teaching ◽  
Starting Point ◽  
Class Viii

Abstractlearning process  good teaching  can create a situation that allows children to learn, so that is the starting point of the success of teaching. The low quality of education depends on the management of the teaching and learning process which can be interpreted as being less effective in the teaching and learning process, the causes: (1) Low learning activities, (2) Inadequate facilities and infrastructure. The case in Solok City Middle School, the low level of student learning activities allegedly influenced the low student learning outcomes. Based on observations on class VIII A which included the superior class had not yet achieved the desired completeness, the class with the least completeness was class VIII B which was 33.33% with KKM 65 criteria. Seeing this reality, teachers were required to motivate students and foster enthusiasm student learning. Therefore, to foster students' enthusiasm for learning, the author tries to apply student learning activities through discussion methods in small groups.Keywords: Learning, discussion AbstrakProses belajar mengajar yang baik dapat menciptakan situasi yang mmemungkinkan anak belajar, sehingga merupakan titik awal keberhasilan pengajaran. Rendahnya mutu pendidikan tergantung pada pengelolaan proses belajar mengajar yang dapat diartikan kurang efektifnya proses belajar mengajar, penyebabnya: (1) Rendahnya aktifitas belajar,  (2) Sarana dan prasarana yang belum memadai. Kasus pada SMP Negeri % Kota Solok rendahnya aktifitas belajar siswa diduga berpengaruh terhadap rendahnya hasil belajar siswa. Berdasarkan pengamatanpada  kelas VIII A yang termasuk kelas unggul belum mencapai ketuntasan yang di inginkan, sedangkan kelas yang paling sedikit ketuntasannya adalah kelas VIII B yaitu sebanyak 33,33 % dengan kriterian KKM 65. Melihat kenyataan tersebut, guru dituntut untuk dapat memotivasi siswa dan menumbuhkan semangat belajar siswa. Karena itu, untuk menumbuhkan semangat belajar siswa, penulis mencoba untuk menerapkan aktivitas belajar siswa melalui metode diskusi dalam kelompok kecil. Kata kunci: Pembelajaran, diskusi

scholarly journals How can electric lighting contribute to human health and well-being?

2021 ◽  
Vol 53 (5) ◽  
pp. 515-522
Author(s):  
P Raynham
Keyword(s):  
Human Health ◽  
Psychological Impact ◽  
Health Benefits ◽  
Well Being ◽  
Health Problems ◽  
Starting Point ◽  
Electric Light ◽  
Health And Well Being ◽  
Hypothetical Explanation

Electric light in buildings may provide some health benefits; however, for most people these benefits are likely to be small. It is possible for electric lighting to cause health problems, if there is too little light or there is glare, but for the most part there is good guidance available and these problems can be avoided. The quality of the lit environment can have a psychological impact and this may in turn impact well-being. A starting point for this is perceived adequacy of illumination. Related lighting metrics are examined and a hypothetical explanation is suggested.

scholarly journals Thermal Physics and Glaucoma II: Preliminary Evidences for a Thermophysical Design of a Possible Visible-Light-Photons Therapy

2021 ◽  
Vol 11 (14) ◽  
pp. 6301
Author(s):  
Giulia Grisolia ◽  
Mariarosa Astori ◽  
Antonio Ponzetto ◽  
Antonio Vercesi ◽  
Umberto Lucia
Keyword(s):  
Quality Of Life ◽  
Thermodynamic Approach ◽  
Equilibrium Thermodynamic ◽  
Pharmacological Treatments ◽  
Light Stimulation ◽  
Cell Behaviour ◽  
Thermal Physics ◽  
Starting Point

Recently, a non-equilibrium thermodynamic approach has been developed in order to model the fundamental role of the membrane electric potential in the cell behaviour. A related new viewpoint is introduced, with a design of a photobiomodulation treatment in order to restore part of the visual field. Here, a first step in experimental evidence of the validity of the thermodynamic approach is developed. This result represents the starting point for future experimental improvements for light stimulation in order to improve the quality of life of the patients. The future possible therapy will be in addition to the pharmacological treatments.

scholarly journals Influence of End Mill Manufacturing on Cutting Edge Quality and Wear Behavior

2021 ◽  
Vol 5 (3) ◽  
pp. 77
Author(s):  
Berend Denkena ◽  
Alexander Krödel-Worbes ◽  
Sascha Beblein ◽  
Markus Hein
Keyword(s):  
Wear Behavior ◽  
Cutting Edge ◽  
End Mills ◽  
Edge Quality ◽  
Manufacturing Process Chain ◽  
The Individual ◽  
Application Specific ◽  
Milling Tools ◽  
Edge Preparation

One of the decisive factors for the performance of milling tools is the quality of the cutting edge. The latter results from the process control of the individual steps along the tool manufacturing process chain, which generally includes the sintering or pressing of the blanks, grinding, cutting edge preparation, and coating of the tools. However, the targeted and application-specific design of the process steps in terms of high economic efficiency is currently limited by a lack of knowledge regarding the influence of the corresponding process parameters on the resulting cutting edge quality. In addition, there is a lack of suitable parameters that adequately represent the characteristics of the cutting edge microtopography. This publication therefore investigates the influence of manufacturing processes on cutting edge quality and wear behavior of end mills. On this basis, different characterization parameters for the cutting edge quality are derived and evaluated with regard to their ability to predict the wear behavior.

scholarly journals High-quality percussion drilling with ultrashort laser pulses

2021 ◽  
Vol 127 (9) ◽  
Author(s):  
A. Feuer ◽  
R. Weber ◽  
R. Feuer ◽  
D. Brinkmeier ◽  
T. Graf
Keyword(s):  
Stainless Steel ◽  
Laser Fluence ◽  
Ablation Threshold ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
High Quality ◽  
Edge Quality ◽  
Ultrashort Laser ◽  
Percussion Drilling

AbstractThe influence of the laser fluence on the quality of percussion-drilled holes was investigated both experimentally and by an analytical model. The study reveals that the edge quality of the drilled microholes depends on the laser fluence reaching the rear exit of the hole and changes with the number of pulses applied after breakthrough. The minimum fluence that must reach the hole’s exit in order to obtain high-quality microholes in stainless steel was experimentally found to be 2.8 times the ablation threshold.

Effect of Nanosized Filler on Matrix Dominated Properties of Fiber Reinforced Epoxy

2011 ◽  
Author(s):  
Yuanxin Zhou ◽  
Shaik Jeelani
Keyword(s):  
Compression Strength ◽  
High Speed ◽  
High Vacuum ◽  
Trapped Air ◽  
Nano Fiber ◽  
Open Hole ◽  
Set Up ◽  
Mechanical Agitator ◽  
Laminar Shear ◽  
Nanosized Filler

In this study, a high-intensity ultrasonic liquid processor was used to obtain a homogeneous molecular mixture of epoxy resin and carbon nano fiber. The carbon nano fibers were infused into the part A of SC-15 (diglycidylether of Bisphenol A) through sonic cavitations and then mixed with part B of SC-15 (cycloaliphatic amine hardener) using a high-speed mechanical agitator. The trapped air and reaction volatiles were removed from the mixture using high vacuum. Nanophased epoxy with 2 wt.% CNF was then utilized in a vacuum assisted resin transfer molding (VARTM) set up with carbon fabric to fabricate laminated composites. The effectiveness of CNF addition on matrix dominated properties of composites has been evaluated by compression, open hole compression and inter-laminar shear. The compression strength, open hole compression strength and ILS were improved by 21%, 23% and 15%, respectively as compared to the neat composite.

scholarly journals Quality and Operations Management in Food Supply Chains: A Literature Review

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Yong He ◽  
Hongfu Huang ◽  
Dong Li ◽  
Chunming Shi ◽  
Sarah J. Wu
Keyword(s):  
Literature Review ◽  
Supply Chains ◽  
Operations Research ◽  
Operations Management ◽  
Food Supply ◽  
Research Field ◽  
Food Supply Chains ◽  
The Past ◽  
Starting Point

We present a literature review on quality and operations management problems in food supply chains. In food industry, the quality of the food products declines over time and should be addressed in the supply chain operations management. Managing food supply chains with operations management methods not only generates economic benefit, but also contributes to environmental and social benefits. The literature on this topic has been burgeoning in the past few years. Since 2005, more than 100 articles have been published on this topic in major operations research and management science journals. In this literature review, we concentrate on the quantitative models in this research field and classify the related articles into four categories, that is, storage problems, distribution problems, marketing problems, and food traceability and safety problems. We hope that this review serves as a reference for interested researchers and a starting point for those who wish to explore it further.

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