Valerio Acanfora | Università della Campania Luigi Vanvitelli (original) (raw)

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Papers by Valerio Acanfora

Research paper thumbnail of Application of an Additive Manufactured Hybrid Metal/Composite Shock Absorber Panel to a Military Seat Ejection System

Applied Sciences

In this work, a preliminary numerical assessment on the application of an additive manufactured h... more In this work, a preliminary numerical assessment on the application of an additive manufactured hybrid metal/composite shock absorber panels to a military seat ejection system, has been carried out. The innovative character of the shock absorber concept investigated is that the absorbing system has a thickness of only 6 mm and is composed of a pyramid-shaped lattice core that, due to its small size, can only be achieved by additive manufacturing. The mechanical behaviour of these shock absorber panels has been examined by measuring their ability to absorb and dissipate the energy generated during the ejection phase into plastic deformations, thus reducing the loads acting on pilots. In this paper the effectiveness of a system composed of five hybrid shock absorbers, with very thin thickness in order to be easily integrated between the seat and the aircraft floor, has been numerically studied by assessing their ability to absorb the energy generated during the primary ejection phase....

Research paper thumbnail of Parametric investigation on the damage behavior of a CFRP omega reinforced panel subjected to asymmetrical flexural load conditions

Materials Today: Proceedings

Research paper thumbnail of On the mechanical behavior of laminated composite plates subjected to compression after impact tests

Materials Today: Proceedings

Research paper thumbnail of Hybrid Metal/Composite Lattice Structures: Design for Additive Manufacturing

Aerospace

This paper introduces a numerical tool developed for the design and optimization of axial-symmetr... more This paper introduces a numerical tool developed for the design and optimization of axial-symmetrical hybrid composite/metal structures. It is assumed that the defined structures are produced by means of two different processes: Additive Layer Manufacturing (ALM) for the metallic parts and Filament Winding (FW) for the composite parts. The defined optimization procedure involves two specific software: ANSYS and ModeFrontier. The former is dedicated to the production of the geometrical and FE models, to the structural analysis, and to the post-process, focusing on the definition of the Unit Cells for the modelling of the metal part. The latter is dedicated to the definition of the best design set and thus to the optimization flow management. The core of the developed numerical procedure is the routine based on the Ansys Parametric Design Language (APDL), which allows an automatic generation of any geometrical model defined by a generic design set. The developed procedure is able to c...

Research paper thumbnail of Cross-Influence between Intra-Laminar Damages and Fibre Bridging at the Skin–Stringer Interface in Stiffened Composite Panels under Compression

Materials

In this paper, the skin–stringer separation phenomenon that occurs in stiffened composite panels ... more In this paper, the skin–stringer separation phenomenon that occurs in stiffened composite panels under compression is numerically studied. Since the mode I fracture toughness and, consequently, the skin–stringer separation can be influenced by the fibre bridging phenomenon at the skin–stringer interface, in this study, comparisons among three different material systems with different fibre bridging sensitivities have been carried out. Indeed, a reference material system has been compared, in terms of toughness performance, against two materials with different degrees of sensitivity to fibre bridging. A robust numerical procedure for the delamination assessment has been used to mimic the skin–stringer separation. When analysing the global compressive behaviour of the stiffened panel, intra-laminar damages have been considered in conjunction with skin–stringer debonding to evaluate the effect of the fibre and matrix breakage on the separation between the skin and the stringer for the ...

Research paper thumbnail of A Numerical–Analytical Approach for the Preliminary Design of Thin-Walled Cylindrical Shell Structures with Elliptical Cut-Outs

Aerospace

The presence of cut-outs within thin-walled shell structures is unavoidable, holes being needed f... more The presence of cut-outs within thin-walled shell structures is unavoidable, holes being needed for the passage of electrical cables, fuel, or just to reduce the weight of the components. Nevertheless, the high stress concentration can lead to a premature collapse of the structure. For this reason, the preliminary design of cylindrical shell structures with holes needs a profound knowledge of the stress distribution for different loading conditions and constraints. In this paper, a parametric study of a fiber-reinforced composite shell cylinder with an elliptical cut-out has been performed. Three different loading conditions were analyzed: Tension, bending, and torsion. Ansys® script, capable of easily generating and analyzing different geometrical configurations, was used to study the dependence of the geometry on the stress distribution near the cut-out. Finally, graphical and analytical relationships were tentatively extrapolated from numerical results, aimed at linking the geome...

Research paper thumbnail of Numerical–Experimental Correlation of Impact-Induced Damages in CFRP Laminates

Applied Sciences

Composite laminates are characterized by high mechanical in-plane properties and poor out-of-plan... more Composite laminates are characterized by high mechanical in-plane properties and poor out-of-plane characteristics. This issue becomes even more relevant when dealing with impact phenomena occurring in the transverse direction. In aeronautics, Low Velocity Impacts (LVIs) may occur during the service life of the aircraft. LVI may produce damage inside the laminate, which are not easily detectable and can seriously degrade the mechanical properties of the structure. In this paper, a numerical-experimental investigation is carried out, in order to study the mechanical behavior of rectangular laminated specimens subjected to low velocity impacts. The numerical model that best represents the impact phenomenon has been chosen by numerical–analytical investigations. A user defined material model (VUMAT) has been developed in Abaqus/Explicit environment to simulate the composite intra-laminar damage behavior in solid elements. The analyses results were compared to experimental test data on ...

Research paper thumbnail of Numerical–Experimental Correlation of Impact-Induced Damages in CFRP Laminates

Applied Sciences

Composite laminates are characterized by high mechanical in-plane properties and poor out-of-plan... more Composite laminates are characterized by high mechanical in-plane properties and poor out-of-plane characteristics. This issue becomes even more relevant when dealing with impact phenomena occurring in the transverse direction. In aeronautics, Low Velocity Impacts (LVIs) may occur during the service life of the aircraft. LVI may produce damage inside the laminate, which are not easily detectable and can seriously degrade the mechanical properties of the structure. In this paper, a numerical-experimental investigation is carried out, in order to study the mechanical behavior of rectangular laminated specimens subjected to low velocity impacts. The numerical model that best represents the impact phenomenon has been chosen by numerical–analytical investigations. A user defined material model (VUMAT) has been developed in Abaqus/Explicit environment to simulate the composite intra-laminar damage behavior in solid elements. The analyses results were compared to experimental test data on ...

Research paper thumbnail of Paper

The sandwich composite panels, due to their highly specific mechanical properties, are widely use... more The sandwich composite panels, due to their highly specific mechanical properties, are widely used in many engineering fields (such as the aeronautical, railways and automotive). In this work, a numerical study is presented on the impact behavior of several sandwich composite panels configurations with polypropylene core, usually adopted for aerospace applications, with the aim to assess their mechanical properties and to make a selection of the best configurations taking into account their multifunctional characteristics. The existing limits in current aeronautical sandwich panels have been assessed and techniques/solutions able to improve (even through the utilization of micro and nano fillers) the multifunctional and structural properties have been explored. Indeed, resistance to fire and resistance to impact events have been selected as the main characteristics of interest for the presented study. Low-speed impact tests (according to the ASTM standards) on sandwich composite panels with polypropylene core have been simulated by means of the commercial FEM software "Abaqus". Low velocity impacts can switch complex damage mechanisms (such as delaminations or large indentations) in composite panels. These damage mechanisms are of major concern from a structural point of view because they can suddenly reduce the loading carrying capability without being visible in programmed visual inspections. As a result of the performed simulations, the low velocity impact induced damage, in terms of delamination and indentation, has been evaluated for several sandwich panels with varying polypropylene core material composition. The outputs have been compared providing a first estimation of the capability to resist to impact event provided by several polypropylene core configurations. The resistance to impact events have been associated to the fire resistance capability of the analyzed material core configurations proving a comprehensive insight on the multifunctional behavior of sandwich composite panels with polypropylene core.

Research paper thumbnail of Application of an Additive Manufactured Hybrid Metal/Composite Shock Absorber Panel to a Military Seat Ejection System

Applied Sciences

In this work, a preliminary numerical assessment on the application of an additive manufactured h... more In this work, a preliminary numerical assessment on the application of an additive manufactured hybrid metal/composite shock absorber panels to a military seat ejection system, has been carried out. The innovative character of the shock absorber concept investigated is that the absorbing system has a thickness of only 6 mm and is composed of a pyramid-shaped lattice core that, due to its small size, can only be achieved by additive manufacturing. The mechanical behaviour of these shock absorber panels has been examined by measuring their ability to absorb and dissipate the energy generated during the ejection phase into plastic deformations, thus reducing the loads acting on pilots. In this paper the effectiveness of a system composed of five hybrid shock absorbers, with very thin thickness in order to be easily integrated between the seat and the aircraft floor, has been numerically studied by assessing their ability to absorb the energy generated during the primary ejection phase....

Research paper thumbnail of Parametric investigation on the damage behavior of a CFRP omega reinforced panel subjected to asymmetrical flexural load conditions

Materials Today: Proceedings

Research paper thumbnail of On the mechanical behavior of laminated composite plates subjected to compression after impact tests

Materials Today: Proceedings

Research paper thumbnail of Hybrid Metal/Composite Lattice Structures: Design for Additive Manufacturing

Aerospace

This paper introduces a numerical tool developed for the design and optimization of axial-symmetr... more This paper introduces a numerical tool developed for the design and optimization of axial-symmetrical hybrid composite/metal structures. It is assumed that the defined structures are produced by means of two different processes: Additive Layer Manufacturing (ALM) for the metallic parts and Filament Winding (FW) for the composite parts. The defined optimization procedure involves two specific software: ANSYS and ModeFrontier. The former is dedicated to the production of the geometrical and FE models, to the structural analysis, and to the post-process, focusing on the definition of the Unit Cells for the modelling of the metal part. The latter is dedicated to the definition of the best design set and thus to the optimization flow management. The core of the developed numerical procedure is the routine based on the Ansys Parametric Design Language (APDL), which allows an automatic generation of any geometrical model defined by a generic design set. The developed procedure is able to c...

Research paper thumbnail of Cross-Influence between Intra-Laminar Damages and Fibre Bridging at the Skin–Stringer Interface in Stiffened Composite Panels under Compression

Materials

In this paper, the skin–stringer separation phenomenon that occurs in stiffened composite panels ... more In this paper, the skin–stringer separation phenomenon that occurs in stiffened composite panels under compression is numerically studied. Since the mode I fracture toughness and, consequently, the skin–stringer separation can be influenced by the fibre bridging phenomenon at the skin–stringer interface, in this study, comparisons among three different material systems with different fibre bridging sensitivities have been carried out. Indeed, a reference material system has been compared, in terms of toughness performance, against two materials with different degrees of sensitivity to fibre bridging. A robust numerical procedure for the delamination assessment has been used to mimic the skin–stringer separation. When analysing the global compressive behaviour of the stiffened panel, intra-laminar damages have been considered in conjunction with skin–stringer debonding to evaluate the effect of the fibre and matrix breakage on the separation between the skin and the stringer for the ...

Research paper thumbnail of A Numerical–Analytical Approach for the Preliminary Design of Thin-Walled Cylindrical Shell Structures with Elliptical Cut-Outs

Aerospace

The presence of cut-outs within thin-walled shell structures is unavoidable, holes being needed f... more The presence of cut-outs within thin-walled shell structures is unavoidable, holes being needed for the passage of electrical cables, fuel, or just to reduce the weight of the components. Nevertheless, the high stress concentration can lead to a premature collapse of the structure. For this reason, the preliminary design of cylindrical shell structures with holes needs a profound knowledge of the stress distribution for different loading conditions and constraints. In this paper, a parametric study of a fiber-reinforced composite shell cylinder with an elliptical cut-out has been performed. Three different loading conditions were analyzed: Tension, bending, and torsion. Ansys® script, capable of easily generating and analyzing different geometrical configurations, was used to study the dependence of the geometry on the stress distribution near the cut-out. Finally, graphical and analytical relationships were tentatively extrapolated from numerical results, aimed at linking the geome...

Research paper thumbnail of Numerical–Experimental Correlation of Impact-Induced Damages in CFRP Laminates

Applied Sciences

Composite laminates are characterized by high mechanical in-plane properties and poor out-of-plan... more Composite laminates are characterized by high mechanical in-plane properties and poor out-of-plane characteristics. This issue becomes even more relevant when dealing with impact phenomena occurring in the transverse direction. In aeronautics, Low Velocity Impacts (LVIs) may occur during the service life of the aircraft. LVI may produce damage inside the laminate, which are not easily detectable and can seriously degrade the mechanical properties of the structure. In this paper, a numerical-experimental investigation is carried out, in order to study the mechanical behavior of rectangular laminated specimens subjected to low velocity impacts. The numerical model that best represents the impact phenomenon has been chosen by numerical–analytical investigations. A user defined material model (VUMAT) has been developed in Abaqus/Explicit environment to simulate the composite intra-laminar damage behavior in solid elements. The analyses results were compared to experimental test data on ...

Research paper thumbnail of Numerical–Experimental Correlation of Impact-Induced Damages in CFRP Laminates

Applied Sciences

Composite laminates are characterized by high mechanical in-plane properties and poor out-of-plan... more Composite laminates are characterized by high mechanical in-plane properties and poor out-of-plane characteristics. This issue becomes even more relevant when dealing with impact phenomena occurring in the transverse direction. In aeronautics, Low Velocity Impacts (LVIs) may occur during the service life of the aircraft. LVI may produce damage inside the laminate, which are not easily detectable and can seriously degrade the mechanical properties of the structure. In this paper, a numerical-experimental investigation is carried out, in order to study the mechanical behavior of rectangular laminated specimens subjected to low velocity impacts. The numerical model that best represents the impact phenomenon has been chosen by numerical–analytical investigations. A user defined material model (VUMAT) has been developed in Abaqus/Explicit environment to simulate the composite intra-laminar damage behavior in solid elements. The analyses results were compared to experimental test data on ...

Research paper thumbnail of Paper

The sandwich composite panels, due to their highly specific mechanical properties, are widely use... more The sandwich composite panels, due to their highly specific mechanical properties, are widely used in many engineering fields (such as the aeronautical, railways and automotive). In this work, a numerical study is presented on the impact behavior of several sandwich composite panels configurations with polypropylene core, usually adopted for aerospace applications, with the aim to assess their mechanical properties and to make a selection of the best configurations taking into account their multifunctional characteristics. The existing limits in current aeronautical sandwich panels have been assessed and techniques/solutions able to improve (even through the utilization of micro and nano fillers) the multifunctional and structural properties have been explored. Indeed, resistance to fire and resistance to impact events have been selected as the main characteristics of interest for the presented study. Low-speed impact tests (according to the ASTM standards) on sandwich composite panels with polypropylene core have been simulated by means of the commercial FEM software "Abaqus". Low velocity impacts can switch complex damage mechanisms (such as delaminations or large indentations) in composite panels. These damage mechanisms are of major concern from a structural point of view because they can suddenly reduce the loading carrying capability without being visible in programmed visual inspections. As a result of the performed simulations, the low velocity impact induced damage, in terms of delamination and indentation, has been evaluated for several sandwich panels with varying polypropylene core material composition. The outputs have been compared providing a first estimation of the capability to resist to impact event provided by several polypropylene core configurations. The resistance to impact events have been associated to the fire resistance capability of the analyzed material core configurations proving a comprehensive insight on the multifunctional behavior of sandwich composite panels with polypropylene core.