Patryk Jakubczak

The impact behavior of aluminum hybrid laminates

Purpose – The purpose of this study was to carry out the analysis of impact resistance for aluminum hybrid laminates and polymer matrix composites reinforced with glass and carbon fibers. Damage modes and damages process under varied impact energies are also presented and discussed. Design/methodology/approach – The subject of examination were fiber metal laminates – FMLs (Al/CFRP and Al/GFRP). The samples were subjected to low-velocity impact by using a drop-weight impact tester. The specimens after impact were examined using non-destructive and destructive inspection techniques. Findings – The hybrid laminates are characterized by higher resistance to impact in comparison to the conventional laminates. The delaminations between composite layers as well as the delaminations on metal/composite interface and lateral cracks are the prevailing type of destruction mechanisms. No significant relationships between metal volume friction coefficient vs response to the impact were recorded for the hybrid laminates...

Comparison of quasi static indentation and dynamic loads of glass and carbon fibre aluminium laminates

Purpose The purpose of this paper was to compare the response of selected hybrid Fibre Metal Laminates (FMLs) in the form of glass and carbon fibre aluminium laminates to dynamic and static loads compared together. Design/methodology/approach The subject of examination was FMLs (Al/CFRP and Al/GFRP). The samples were subjected to low-velocity impact and quasi-static indentation. The response of laminates to the both types of loads was evaluated by comparison of force – displacement diagrams including the values of maximum forces as well as the extent and nature of structure degradation as a result of loads. Findings In case of Al/GFRP laminates, the analysis of characteristic relations, i.e. force – displacement and the impactor influence area in case of indentation and impact confirmed that certain parameters, i.e. the values of maximum force transferred by laminate, destruction surface area and destruction mechanisms are consistent after static and dynamic tests. Significant differences were found in destruction scale in Al/GFRP laminates despite considerable fitting of force – displacement diagrams to static and dynamic tests. Destruction surface area observed in FML carbon laminates subjected to dynamic loads was significantly smaller than after indentation but perforation area occurring at the unloaded side was much more extensive. Practical implications Research issues in the scope of dynamic loads by means of concentrated force in composite materials and interpretation of the effects of their impacts are extremely complex. Therefore, the attempts are made to predict the resistance to dynamic loads by means of concentrated force using statistical research methods. The test results might be useful for the design and simulations of FMLs applications in aerospace. Originality/value From the analysis of available literature, it appears that there are no studies exploring the issue of forecasting or comparison the effects of static and dynamic tests for hybrid FMLs. The new hybrid materials like FMLs have different mechanisms of damage initiation and propagation as a result of impact, in comparison to classic composite materials. It means that possibilities of using the static loads to predict impact resistance should be known well for all type of FMLs. Actually, there is no research about static indentation in relation to low-velocity impact of aluminium-carbon laminates. This situation encouraged the authors of the present study to undertake research in this scope. The results can demonstrate and explain why prediction of impact resistance of FMLs by using static indentation is uncertain and not always valuable.

Experimental investigation on the influence of fibers orientation on the failure of carbon hybrid laminates

Purpose – The purpose of this paper is to present microstructural and fractographic analysis of damage in aluminum (2024T3)/carbon-fiber reinforced laminates (AlC) after static tensile test. The influence of fiber orientation on the failure was studied and discussed. Design/methodology/approach – The subject of examination was AlC. The fiber–metal laminates (FMLs) were manufactured by stacking alternating layers of 2024-T3 aluminum alloy (0.3 mm per sheets) and carbon/epoxy composites made of unidirectional prepreg tape HexPly system (Hexcel, USA) in [0], [± 45] and [0/90]S configuration. The fractographic analysis was carried out after static tensile test on the damage area of the specimens. The mechanical tests have been performed in accordance to ASTM D3039. The microstructural and fractographic analysis of FMLs were studied using optical (Nikon SMZ1500, Japan) and scanning electron microscope (Zeiss Ultra Plus, Germany). Findings – FMLs based on aluminum and carbon/epoxy composite are characterized by...

The influence of fibre orientation in aluminium–carbon laminates on low-velocity impact resistance

The objective of this study was to assess the influence of fibre orientation in hybrid fibre metal laminates based on aluminium and carbon fibres on the impact of low-velocity impact. The analysis was conducted on the basis of fibre metal laminate impact resistance criteria, including impact force, energy absorption, bending stiffness, damage area and failure. To assess the resistance of various aluminium–carbon laminates, qualitative and quantitative evaluation criteria were employed, including the shape of the force–time curve, characteristic impact forces, energy absorption, bending stiffness, damage area and external failure analysis. Among others, authors concluded that no explicit influence of the composite layer fibre orientation on the shape and value of characteristic forces was observed. It was found that the fibre orientation and the changing number of interfaces of low durability show no explicit influence on the size and shape of delaminations.

Structure and chemistry of fiber metal laminates

Fiber metal laminates (FMLs) are a modern group of hybrid composites consisting of metal sheets and layers of polymer composite reinforced with fiber. Desirable properties are being get throuwegh the selection of components and the configuration of layers. Nowadays, aluminum/glass fiber epoxy composite laminates type glass reinforced are most popular, but other metallic and fiber composite materials as components are widely examined. The adhesion of these components is achieved in manufacturing process during curing in autoclave or in vacuum bag using out-of-autoclave method. The metal layers are specially pretreated before the process of bonding with fibers/epoxy prepreg. A pretreatment is essential to promote one or several of the adhesion mechanisms (i.e., mechanical interlocking, physisorption, chemisorption) both improving the strength of the adhesive joint. The quality of FML depends on macrostructure and microstructure of composite—voids presence and their size, fiber distribution, and cohesion of plies; microstructure, topography, and the physical and chemical properties of metal surface; microstructure of interface—especially presence of delamination. Therefore, the macro- and microstructure characterization is very important as the first step for predicting the properties of FMLs.

Properties and characterization of fiber metal laminates

Abstract Fiber metal laminates are hybrid composites consisting of alternating thin layers of metal sheets and fiber-reinforced composites for advanced aerospace structural applications. FML possess superior properties of both metals and fibrous composite materials. Fiber metal laminates are characterized by low density, excellent impact resistance, high strength-static and fatigue properties, corrosion, and fire resistance. Specific fiber metal laminates are determined by the type of metal alloy, fiber/resin system, layer thickness, number of layers in the laminate, stacking sequence, and fiber orientations. The chapter presents mechanical and environmental properties and characterization of various laminates. Applications and future trends in FML are also discussed.

Forming of thin-walled profiles made of FML in autoclave process

Purpose The purpose of the study was to develop the forming methodology for FML laminates with complex shapes, based on aluminium and epoxy – glass composite. Design/methodology/approach The subject of research encompassed Al/GFRP fibre metal laminates. Autoclave process has been selected for FML profiles production. Manufacturing process was followed by quality analysis for laminates produced. Findings The achievement of high stability and dimensional tolerance of thin - walled FML laminates is ensured by developed technology. The values of selected sections angles are significantly limited as a result of forming of FML laminates through the components performing. Failure to adhere to technological recommendations and to high regime of developer technology may lead to the occurrence of defects in FML. Practical implications Thin-walled composite structures could be applied in light weight constructions, such as aircraft structures, which must meet rigorous requirements with regard to operation under comp...

Impact resistance and damage of fiber metal laminates

Abstract Impact resistance and damage tolerance is one of the most attractive features of fiber metal laminates (FMLs). Adhesive connection of elastic–plastic metal and stiff fibrous composite provides excellent energy absorption and relatively low damage, especially after low-velocity impact. However, some damage occurs in laminate. Frequently, barely visible impact damage is associated with internal damaged area of the composite and composite–metal interphase, with numerous delaminations, matrix cracks, fiber fracture, and metal failure. However, there are many factors influencing the damage of FMLs under low-velocity impact such as type of metal and fibers, fibers arrangement, and impact conditions. The ways to improve their properties to withstand this type of loading could be of particular importance in aerospace structures and other applications. The methods of impact examinations, quantitative impact resistance determination, damage assessment, and numerical calculations of damage prediction of different FMLs will be discussed.