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The combination of fibre metal laminates (FML) and sandwich structures can significantly increase the performance under impact of FMLs. The goal of this work was to create a material that will combine the superior properties of FMLs and foam sandwich structures in terms of the impact resistance and simultaneously have lower density and fewer disadvantages related to the manufacturing. An extensive impact testing campaign has been done using conventional fibre metal laminates (carbon- and glass-based) and in the proposed fibre foam metal laminates to assess and compare their behaviour. The main difference was observed in the energy absorption mechanisms. The dominant failure mechanism for fibre foam laminates is the formation of delaminations and matrix cracks while in the conventional fibre metal laminate the main failure mode is fibre cracking due to high local stress concentrations. The reduction in the fibre cracking leads to a better after-impact resistance of this type of structure improving the safety of the structures manufactured with these materials.

Fibre metal laminates (FML) are the modern hybrid materials with potential wide range of applications in aerospace technology due to their excellent mechanical properties (particularly fatigue strength, resistance to impacts) and also excellent corrosion resistance. The study describes the resistance to low velocity impacts in Ti/CFRP laminates. Tested laminates were produced in autoclave process. The laminates were characterized in terms of their response to impacts in specified energy range (5J, 10J, 20J). The tests were performed in accordance with ASTM D7137 standard. The laminates were subjected to impacts by means of hemispherical impactor with diameter of 12,7 mm. The following values have been determined: impact force vs. time, maximum force and the force at which the material destruction process commences (Pi). It has been found that fibre titanium laminates are characterized by high resistance to impacts. This feature is associated with elasto-plastic properties of metal and high rigidity of epoxy - fibre composite. It has been observed that Ti/CFRP laminates are characterized by more instable force during impact in stage of stabilization of impactor-laminate system and stage of force growth that glass fibre laminates. It has been observed more stable force decrease in stage of stress relaxation and withdrawal of the impactor. In energy range under test, the laminates based on titanium with glass and carbon fibres reinforcement demonstrate similar and high resistance to low-velocity impact, measured by means of failure initiation force and impact maximum force.

The purpose of the work was the effect of metal volume fraction of fiber metal laminates on damage after dynamic loads based upon the example of innovative hybrid titanium−carbon composite laminates. The subject of the study was metal−fiber hybrid titanium−carbon composite laminates. Four types of hybrid titanium−carbon laminates were designed with various metal volume fraction coefficient but constant thickness. Based on the results, it can be stated that changes in the metal volume fraction coefficient in the range of 0.375−0.6 in constant thickness titanium−carbon composite laminates do not significantly affect their resistance to impacts in the energy range of 5−45 J. It was concluded that there were no significant differences in maximum force values, total contact time, and damage range. Some tendency towards a reduction in the energy accumulation capacity was observed with an increase in thickness of the metal part in relation to the total thickness of the laminate, especially in the lower impact energy range. This can result in the lower bending stiffness of laminates with lower metal content and potential elastic strain of the composite part before the initiation of the fiber damage process.

• The purpose of the study was the multifaceted and complex analysis of the impact behaviour of hybrid titanium glass fibres laminates (HTGL) based on the experiment method. Moreover the appropriate model to prediction of impact damage resistance was proposed. Different quantitative and qualitative criteria were used to measure and compare the impact behaviour of HTGL. • Based on impact parameters and damage analysis of HTGL after impact, FEM model was proposed to predict the impact resistance of HTGL. • Based on the obtained results of experimental studies it was proven that fibre metal laminates based on titanium and glass-epoxy composite are characterised by high resistance to low-velocity impact. • Greater resistance of these laminates to damage propagation and perforation was noted for the impact with a spherical indenter in comparison to the previously used GLARE laminates. • Three aspects of mechanical response of FMLs, such as metal properties, composite properties and metal-composite interphase were used in the FEM simulation. Results of numerical analyses indicate the correctness of the adopted calculation assumptions and the study procedure itself. Fibre metal laminates (FML) constitute a group of hybrid materials made of alternating layers of metal and fibre polymer composite. One of the more prospective materials of the next FML generation is a laminate based on titanium and glass or carbon fibres. The use of titanium increases laminate stiffness in comparison to laminates based on aluminium alloys and significantly increases the corrosion resistance and impact properties. The purpose of the study was a multifaceted and complex analysis of the impact behaviour of hybrid titanium glass fibres laminates (HTGL) based on the experiment and modelling methods. Based on the obtained results of experimental studies it was proven that fibre metal laminates based on titanium and glass-epoxy composite are characterised by high resistance to low-velocity impact within the range of energy of 2.5–30 J at least, expressed by the criteria of maximum force, deformations, work performed by the indenter, impact energy absorption capacity, and the parameters describing the extent of damage after impact. The obtained results of numerical analyses indicate the correctness of the adopted calculation assumptions and the study procedure itself. [ABSTRACT FROM AUTHOR]

• The objective were Hybrid Titanium Carbon Laminates as a second generation of FML. • The fibre orientation in HTCL has a significant influence on damage propagation. • Dominant failure occurs at the metal/composite and composite/composite interfaces. • HTCL can be an appropriate solution for materials under dynamic loads. Impact resistance is one of the more critical and important features of composite materials used in the aerospace industry. The objective of work was to evaluate the hybrid titanium carbon laminate resistance to dynamic loads. The paper utilizes numerous criteria for evaluation of impact behaviour of materials, including force change, energy absorption characteristics and failure identification. To thoroughly analyze the damage mechanism, a detailed fractography of laminate destruction was performed. Moreover, an empirical model for determining the universal impact behaviour coefficient of fibre metal laminate (FML) was proposed. The first significant force fluctuations prove to reach the laminate's impact resistance limit as caused by the initiation of cracking of respective layers and the consequent reduction of laminate rigidity. A growing proportion of absorbed energy in the case of growing impact energies, from some 50% in case of 2.5 J of energy, up to circa 80% in case of 30 J of energy was recorded. Reduction of interlayers with crossing fibers fosters the creation of cracks in the lower layer of titanium due to the limited capability of partial absorption of energy through delamination. [ABSTRACT FROM AUTHOR]