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The development of fiber metal laminates to multi-functional materials by embedding heater elements in the laminate extends their field of application. Fiber metal laminates with embedded heater elements are likely to be used for the de- and anti-icing of leading edges in aircraft as they combine structural and heating functions. Hence, those heated fiber metal laminates are exposed to frequent temperature changes when the de- or anti-icing devices are switched on. In order to examine the possible effects of thermal fatigue loading on the material characteristics, a thermal cycling setup was developed. The experimental setup has the ability to perform thermal cycling tests of materials with and without embedded heater elements. For structural materials, the thermal cycling setup provides external cooling and external heating using Peltier elements. For multi-functional materials (materials with embedded heater elements), the experimental setup enables thermal cycling tests by providing external cooling using Peltier elements and internal heating using the embedded heater mesh. The multi-functional material which is thermal cycled in this study is heated GLARE (Glass Laminate Aluminum Reinforced Epoxy). The temperatures recorded by thermo couples at different specimen positions are presented. The thermal cycle times were about 62 s for temperature cycles from 0°C to 60°C and 2 mm thick heated GLARE specimens. Similar thermal cycling times can be reached for both external cooling and heating and external cooling and internal heating. However, the use of Peltier elements to heat the specimens outer surfaces (external heating) leads to more homogeneous temperature distributions than when using the embedded heater elements as internal heating. The presented experimental setup can be adapted to different specimen dimensions, enables thermal cycling of multiple specimens of the same material, and is applicable for different temperature ranges and heating or cooling rates., Aerospace Structures & Materials, Aerospace Engineering

The development of fiber metal laminates to multi-functional materials by embedding heater elements in the laminate extends their field of application. Fiber metal laminates with embedded heater elements are likely to be used for the de- and anti-icing of leading edges in aircraft as they combine structural and heating functions. Hence, those heated fiber metal laminates are exposed to frequent temperature changes when the de- or anti-icing devices are switched on. In order to examine the possible effects of thermal fatigue loading on the material characteristics, a thermal cycling setup was developed. The experimental setup has the ability to perform thermal cycling tests of materials with and without embedded heater elements. For structural materials, the thermal cycling setup provides external cooling and external heating using Peltier elements. For multi-functional materials (materials with embedded heater elements), the experimental setup enables thermal cycling tests by providing external cooling using Peltier elements and internal heating using the embedded heater mesh. The multi-functional material which is thermal cycled in this study is heated GLARE (Glass Laminate Aluminum Reinforced Epoxy). The temperatures recorded by thermo couples at different specimen positions are presented. The thermal cycle times were about 62 s for temperature cycles from 0°C to 60°C and 2 mm thick heated GLARE specimens. Similar thermal cycling times can be reached for both external cooling and heating and external cooling and internal heating. However, the use of Peltier elements to heat the specimens outer surfaces (external heating) leads to more homogeneous temperature distributions than when using the embedded heater elements as internal heating. The presented experimental setup can be adapted to different specimen dimensions, enables thermal cycling of multiple specimens of the same material, and is applicable for different temperature ranges and heating or cooling rates., Aerospace Structures & Materials, Aerospace Engineering

The impact response of fiber metal laminates (FMLs), has been investigated with experiments and numerical simulations, which is reported in this article. Low-velocity impacts were carried out to study the effects of metal type and thickness within FMLs. Glare5-3/2 laminates with two aluminum layer thicknesses and a similar FML containing magnesium sheets were impacted by drop weight tests. Also, a major part of this study was to accomplish a dynamic non-linear transient analysis to study the impact response of FMLs using the commercial finite element (FE) analysis code ABAQUS. By reviewing different approaches of modeling constituents of an FML, it is shown that the appropriate selection of elements hasmore significant role than failure criterion to predict acceptable results for this type of laminate and loading. The good agreement obtained between experimental and numerical results verifies the possibility of relatively simpler simulation by FE-analysis to predict overall response of FMLs under impact loading., Aerspace Structures and Materials, Aerospace Engineering

The design of complex systems in today’s aerospace domain requires a balance between the ever-increasing complexity of the supporting technology and the drive to develop those systems in a compressed timeframe. The performance knowledge of a preliminary design must shift backwards in the lifecycle in order to exploit that knowledge when there is still freedom in the design. Design of aerospace structures with fiber metal laminates (FML) represents one such area where the increased design freedom comes at a cost of increased design complexity. The potential benefits of FML technology, however, demand a solution to this design challenge. FMLs require a different approach to design and manufacturing that so far has been only moderately explored for possible automation. In order to support design of an FML wing, a tailored design methodology and prototyping tools are needed. The quantitative systems engineering field of knowledge based engineering (KBE) provides a solution. A KBE approach, leveraging parametric, geometry-based modeling and expert FML manufacturability knowledge, can work within a design framework to automate many of the non-creative activities of the FML designer, such as initial layup design and manufacturability rule application. This research seeks to frame the FML wing design process, develop critical KBE design modules tailored for FML knowledge, and illustrate their utility in the balance of aerospace structure weight and cost., Aerospace Materials and Manufacturing (AMM); Aerospace Structures & Design Methodologies (AS&DM), Aerospace Engineering

This effort explored the mechanical characteristics and economic feasibility of using the fiber metal laminate, GLARE-3, as a secondary aircraft structure; specifically the cargo floor of a C-130. The mechanical properties were determined through static four point bending and tensile testing and dynamic impact testing. Aggregate behavior of the constituent materials was predicted using a model which consisted of Mass Volume Fraction (MVF) and Classical Laminated Plate Theory (CLPT) methods using known values for the constituents. Static testing was conducted on coupon-level specimens using standardized testing procedures. Static tensile tests were conducted on specimens with four different fiber orientations, 0?, 22.5?, 45?, and 90?, while static bending tests were conducted on fiber orientations of 0? and 90?. Two series of impact tests were performed on both GLARE-3 and 2024 T3 aluminum using 4 inch wide strips to show impact damage progression. Data for the economic analysis was gathered from existing literature and cost data was analyzed over a 30 year period for both GLARE and Aluminum. Analysis of the data proved the use of GLARE-3 as a potential cargo floor material was mechanically and economically feasible with the material paying for itself within the first year of its use., The original document contains color images.

The fatigue life of an aircraft is dependent on the loads of the aircraft service spectrum. Due to the variable nature of the load spectrum, fatigue crack growth is accelerated and decelerated by interaction effects. Interaction effects, like crack closure, make an accurate prediction of the fatigue life challenging. The material GLARE, a laminate built up of aluminium and glass fibre layers, is used in the fuselage of the Airbus A380. Fatigue crack propagation is the dominant part of the fatigue life of GLARE structures. For GLARE, crack closure is thought to be a significant interaction effect and is not yet investigated for GLARE. In this thesis crack closure in GLARE is investigated. The study limits itself to crack growth in simple coupon specimens with through cracks, loaded in the longitudinal direction in a lab air environment at room temperature. The investigation started with a literature study on fatigue, interaction effects, crack closure, and load variations in both metals and GLARE. A test plan is proposed and executed from which the test results are analysed and conclusions drawn. Crack closure is the result of crack tip plastic deformation. As the crack propagates, plastic deformation comes in the wake and closes the crack. This reduces the effective stress range and consequently the crack growth rate. Load variations in CA cycles lead to a crack growth acceleration or decelerations that can be partly explained by crack closure. For two stress level sequences, the crack growth rate acceleration or deceleration can be explained by crack closure and compatibility of the crack front geometry. Crack growth in GLARE is a self-balancing mechanism with delamination growth between the aluminium- and fibre layers. The fibres “bridge” the crack by leading the stresses through it. This results in an approximately constant stress intensity factor and crack growth rate for long ranges of crack lengths. Crack closure in GLARE is investigated with two tests series, Mechanics, Aerospace Structures & Materials, Aerospace Engineering

Aerospace Engineering

Aerospace Engineering

První část práce s názvem „Hybridní lepené spoje kovových a kompozitních materiálů“ obsahuje popis povrchových úprav adherendů. Rovněž je uveden aktuální ucelený přehled lepidel používaných pro spojování kompozitních a kovových adherendů. Druhá část práce je zaměřena na zkoušky smykové pevnosti hybridních spojů. Byl zkoumán vliv tloušťky adherendu, délky přeplátování a vliv přípravy povrchu na smykovou pevnost spoje. Naměřené závislosti jsou ověřeny FE analýzami s dostatečnou přesností. Poznatky a závěry uvedené v práci je možné využít pro optimální návrh hybridního spoje duralu a kompozitu., The first part of the diploma thesis with name „Hybrid adhesive bonded joints of metals and composite materials“ comprise surface pretreatment review. There is also mentioned current review of adhesives for composite and aluminium adherends. The second part of the thesis is dedicated to lap hybrid joint shear strength tests. The effects of adherend thickness, overlap lenght and surface pretreatment on shear strength were investigated. Measured parameters of hybrid joints are proved with a FE analysis with enough accuracy. Conclusions could be used for optimum design of hybrid joint with aluminium and composite adherends.

První část práce s názvem „Hybridní lepené spoje kovových a kompozitních materiálů“ obsahuje popis povrchových úprav adherendů. Rovněž je uveden aktuální ucelený přehled lepidel používaných pro spojování kompozitních a kovových adherendů. Druhá část práce je zaměřena na zkoušky smykové pevnosti hybridních spojů. Byl zkoumán vliv tloušťky adherendu, délky přeplátování a vliv přípravy povrchu na smykovou pevnost spoje. Naměřené závislosti jsou ověřeny FE analýzami s dostatečnou přesností. Poznatky a závěry uvedené v práci je možné využít pro optimální návrh hybridního spoje duralu a kompozitu., The first part of the diploma thesis with name „Hybrid adhesive bonded joints of metals and composite materials“ comprise surface pretreatment review. There is also mentioned current review of adhesives for composite and aluminium adherends. The second part of the thesis is dedicated to lap hybrid joint shear strength tests. The effects of adherend thickness, overlap lenght and surface pretreatment on shear strength were investigated. Measured parameters of hybrid joints are proved with a FE analysis with enough accuracy. Conclusions could be used for optimum design of hybrid joint with aluminium and composite adherends.

První část práce s názvem „Hybridní lepené spoje kovových a kompozitních materiálů“ obsahuje popis povrchových úprav adherendů. Rovněž je uveden aktuální ucelený přehled lepidel používaných pro spojování kompozitních a kovových adherendů. Druhá část práce je zaměřena na zkoušky smykové pevnosti hybridních spojů. Byl zkoumán vliv tloušťky adherendu, délky přeplátování a vliv přípravy povrchu na smykovou pevnost spoje. Naměřené závislosti jsou ověřeny FE analýzami s dostatečnou přesností. Poznatky a závěry uvedené v práci je možné využít pro optimální návrh hybridního spoje duralu a kompozitu., The first part of the diploma thesis with name „Hybrid adhesive bonded joints of metals and composite materials“ comprise surface pretreatment review. There is also mentioned current review of adhesives for composite and aluminium adherends. The second part of the thesis is dedicated to lap hybrid joint shear strength tests. The effects of adherend thickness, overlap lenght and surface pretreatment on shear strength were investigated. Measured parameters of hybrid joints are proved with a FE analysis with enough accuracy. Conclusions could be used for optimum design of hybrid joint with aluminium and composite adherends.

První část práce s názvem „Hybridní lepené spoje kovových a kompozitních materiálů“ obsahuje popis povrchových úprav adherendů. Rovněž je uveden aktuální ucelený přehled lepidel používaných pro spojování kompozitních a kovových adherendů. Druhá část práce je zaměřena na zkoušky smykové pevnosti hybridních spojů. Byl zkoumán vliv tloušťky adherendu, délky přeplátování a vliv přípravy povrchu na smykovou pevnost spoje. Naměřené závislosti jsou ověřeny FE analýzami s dostatečnou přesností. Poznatky a závěry uvedené v práci je možné využít pro optimální návrh hybridního spoje duralu a kompozitu., The first part of the diploma thesis with name „Hybrid adhesive bonded joints of metals and composite materials“ comprise surface pretreatment review. There is also mentioned current review of adhesives for composite and aluminium adherends. The second part of the thesis is dedicated to lap hybrid joint shear strength tests. The effects of adherend thickness, overlap lenght and surface pretreatment on shear strength were investigated. Measured parameters of hybrid joints are proved with a FE analysis with enough accuracy. Conclusions could be used for optimum design of hybrid joint with aluminium and composite adherends.

První část práce s názvem „Hybridní lepené spoje kovových a kompozitních materiálů“ obsahuje popis povrchových úprav adherendů. Rovněž je uveden aktuální ucelený přehled lepidel používaných pro spojování kompozitních a kovových adherendů. Druhá část práce je zaměřena na zkoušky smykové pevnosti hybridních spojů. Byl zkoumán vliv tloušťky adherendu, délky přeplátování a vliv přípravy povrchu na smykovou pevnost spoje. Naměřené závislosti jsou ověřeny FE analýzami s dostatečnou přesností. Poznatky a závěry uvedené v práci je možné využít pro optimální návrh hybridního spoje duralu a kompozitu., The first part of the diploma thesis with name „Hybrid adhesive bonded joints of metals and composite materials“ comprise surface pretreatment review. There is also mentioned current review of adhesives for composite and aluminium adherends. The second part of the thesis is dedicated to lap hybrid joint shear strength tests. The effects of adherend thickness, overlap lenght and surface pretreatment on shear strength were investigated. Measured parameters of hybrid joints are proved with a FE analysis with enough accuracy. Conclusions could be used for optimum design of hybrid joint with aluminium and composite adherends.

První část práce s názvem „Hybridní lepené spoje kovových a kompozitních materiálů“ obsahuje popis povrchových úprav adherendů. Rovněž je uveden aktuální ucelený přehled lepidel používaných pro spojování kompozitních a kovových adherendů. Druhá část práce je zaměřena na zkoušky smykové pevnosti hybridních spojů. Byl zkoumán vliv tloušťky adherendu, délky přeplátování a vliv přípravy povrchu na smykovou pevnost spoje. Naměřené závislosti jsou ověřeny FE analýzami s dostatečnou přesností. Poznatky a závěry uvedené v práci je možné využít pro optimální návrh hybridního spoje duralu a kompozitu., The first part of the diploma thesis with name „Hybrid adhesive bonded joints of metals and composite materials“ comprise surface pretreatment review. There is also mentioned current review of adhesives for composite and aluminium adherends. The second part of the thesis is dedicated to lap hybrid joint shear strength tests. The effects of adherend thickness, overlap lenght and surface pretreatment on shear strength were investigated. Measured parameters of hybrid joints are proved with a FE analysis with enough accuracy. Conclusions could be used for optimum design of hybrid joint with aluminium and composite adherends.