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Effective Machining Of Fiber Reinforced Composite Materials
Sedláček, Jan ; Janáč, Alexander (referee) ; Vrba, Vladimír (referee) ; Klement, Josef (referee) ; Humár, Anton (advisor)
The objectives for this dissertation are to push forward the current state of knowledge in the area of machining fiber-reinforced plastic (FRP). The most common machining operation performed on these materials is drilling owing to the need for component assembly in mechanical pieces and structures. Among the defects caused by drilling, delamination appears as to be of the most critical and may occur at both the entrance and exit plane. A number of theoretical and experimental studies have been made to create an analytical model of delamination in composite laminates. In this dissertation, the critical thrust force (force which initiates the delamination) is predicted using linear elastic fracture mechanics - assuming Mode I. Delamination is investigated by studying the evolution of feed force and torque applied by the tool on the workpiece. A four components piezoelectric dynamometer KISTLER 9272 with special PC-software is used for measuring and evaluating of torque and cutting forces, when drilling two different composite materials: carbon/epoxy laminate fabricated by hand lay-up technique and glass/polyester composite made by pultrusion. Wear mechanisms and location of the wear on the tool are also investigated (with respect to cutting material). The tool wear is measured with help of a common workshop microscope and recorded with scanning electron microscope PHILIPS XL30. Drilling experiments are performed to give complex technical information (i.e. cutting conditions, tool geometry, tool wear and so on) which enables efficient machining of composite materials. Delamination-free drilling is given special emphasis in the experiments. Methods of statistical analysis (DOE) are used to determine which factors have the most influence on delamination.
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Application of microwave heating for curing of adhesives and composite materials
Wagnerová, Klára ; Urík, Tomáš (referee) ; Klement, Josef (advisor)
This bachelor's thesis concerns the microwave technology and the possibilities for its use in the curing of adhesives and composite materials. The thesis is divided into two main parts. The first part summaries theoretical findings about microwave technology. There is the principle of microwave heating described as well as constructions of microwave devices. Also the possibilities of using this technology for the curing of composite structures are mentioned. The second part of the thesis is devoted to the practical verification of the theoretical assumptions.
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Interlaminar fracture toughness of fiber reinforced plastics
Vodička, Vít ; Mališ, Michal (referee) ; Klement, Josef (advisor)
Cílem této diplomové práce je lépe porozumět konceptu únavového poškození damage tolerance zmapováním všech možných vlivů na lomovou houževnatost vláknového kompozitu s polymerní matricí. Toho je dosaženo provedením zkoušek za různých podmínek (např. změna parametrů měření, mód zatížení, pořadí vrstev a materiál) a monitorováním odlišností v šíření trhliny. Na základě dat získaných během těchto testů je určena lomová houževnatost. Potenciální rozdíly jsou zkonzultovány a porovnány s ostatními vzorky.
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Dynamic Properties of Combined Rivet and Adhesive Bonded Joints
Urík, Tomáš ; Samek, Radko (referee) ; Petrásek, Miloslav (referee) ; Klement, Josef (advisor)
The improvement of static properties of combined rivet and adhesive bonded joints have been proven by several authors [1, 2]. On the other side, dynamic properties of joints (for example fatigue and corrosion) significantly affect final function of structures during their service life. In this thesis, the combine joints created by blind rivets and hyper elastic sealant are solved. Complex description of dynamic properties of this particular combined joining technology has not been publicised, yet. Description of sealant layer influence on stress concentration in rivet hole regions is one of the main goal of this work. The next stage of the thesis is focused on the influence of above mentioned sealant layer on fatigue properties of combined blind rivet and solid countersunk rivet joints. Stress strain analysis of rivet and combined joints done by FE analysis and by experimental optical measurement of strain field proved that hyper elastic sealant layer has a positive effect on decreasing of stress peaks in rivet hole regions. This findings are in direct compliance with fatigue measurement of combined joint (AAPL). The influence of applied sealant in this combined joints improved fatigue properties by twenty percentage increasing of stress to failure in comparison with rivet joints.
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Evaluation of dynamic damage of composite structure
Štefanovič, Peter ; Jetela, Václav (referee) ; Klement, Josef (advisor)
The first part of the diploma thesis with name „Evaluation of dynamic damage of composite structure“ focuses on designing device for impact experiments and suitable laminate samples made from prepregs. The conditions and problems of impact tests are also demonstrated here. The second part of the thesis deals with non-destructive control of damaged specimens based on thermography. This is mainly the extent of defects in the impaired area and the evaluation of results using the pulse infrared thermography method. Finally, the relative deviation in the crack size comparison between the visual method and thermographic are compared. Consequently, the residual strength of the damaged samples against undamaged specimens are compared using bending tests.
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Database for laboratories and exercises in the course Aircraft Manufacture
Horčička, Marek ; Löffelmann, František (referee) ; Klement, Josef (advisor)
This bachelor thesis dealts with a selected part of the database for laboratories and exercises in the course of Aircraft Manufacture. The first part consists of a basic overview of aviation materials and the conditions of their thermal processing. It is about the technology of heat treatment of steel and alluminium alloys. In addition, the substrates for profile and tube forming technology are presented. The whole bachelor thesis is elaborated in accordance with the content of the course in the subject Aircraft Manufacture.
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Testing of Aircraft Jet Engines
Trusík, Vojtěch ; Klement, Josef (referee) ; Šplíchal, Miroslav (advisor)
This bachelor final project is composed from two main parts. The first part is focused on describing of aviation agencies, function of jet engine, testing bed and desribing of testing of jet engines. The second part devote to application of CS-E prescription on the jet engine TJ-100 C.
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Aircraft jet engines with adaptive cycle
Heczko, Nikodem ; Šplíchal, Miroslav (referee) ; Klement, Josef (advisor)
In this final bachelor thesis is a basic overview and distribution of gas turbine engines, including a brief description of their function. The work is focused on jet engines with adaptive cycle. It introduces benefits of their use as aviation fuel units in terms of efficiency and description of possible ways to design solutions. Secondly, it analyzes the very principle of adaptive cycle and its implementation on the engine YF120. In conclusion are presented research programs dealing with adaptive cycle.
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Fracture Toughness of Composite with Al-matrix and Carbon Fibres
Michalička, Jan ; Klement, Josef (referee) ; Molliková, Eva (advisor)
Abstract The objective of this study was a values evaluation of fracture toughness of fiber-metal laminates (FML) compounded from carbon fibers in epoxy matrix and aluminium plates of lay-up 6/5. Samples with unidirectional and bidirectional orientation were tested experimentally. In the case of unidirectionally oriented samples an effect of moisture absorption to epoxy matrix on the values of fracture toughness was reviewed. A fracture toughness calculation was realized by COD method firstly. A bigger pop-ins in F – COD diagram as critical moments for "delta"c evaluation were considered; it was determined by 5% tangential line. It was found out, that results of this measurement weren’t in agreement with plane deformation condition and for this the results couldn’t be rated as fracture toughness "delta"Ic. A method of J integral for fracture toughness evaluation was used consequently. A test of elastic compliance changes before J integral calculation by all of samples was performed. Beginning of stable grow of crack was determined by this method. A critical forces Fc from beginnings were established, which were used for calculation of Jc. A functional dependence of elastic compliance on crack opening had specific waved shape before its linear (up to exponential) grow. It was observed in all cases. The critical forces Fc from the end of “wave” preceding the continual grow of compliance were determined. Equations stated in standards for J integral calculation were used, which are for metal materials normally used. Despite this was found out all of results of Jc were in good agreement with plane deformation condition and could be rated as fracture toughness JIc. In this study were found out these pieces of knowledge about fracture toughness of FML CARE: Unidirectional CARE had fracture toughness JIc about 76 kJ/m^2 and the same type but with bigger amount of absorbed moisture had JIc about 4 % higher. In this case negative moisture influences on CARE weren’t found. Bidirectional CARE had fracture toughness JIc about 31 kJ/m^2; it was about 65 % less then in the case of unidirectional CARE
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