Full composites hydrogen fuel cells unmanned aerial vehicle with telescopic boom

Carrera, E.,Verrastro, M.,Boretti, Alberto Techno-Press 2022 Advances in aircraft and spacecraft science Vol.9 No.1

This paper discusses an improved unmanned aerial vehicle, UAV, configuration characterized by telescopic booms to optimize the flight mechanics and fuel consumption of the aircraft at various loading/flight conditions.The starting point consists of a full-composite smaller UAV which was derived by a general aviation ultralight motorized aircraft ULM. The present design, named ToBoFlex, extends the two-booms configuration to a three tons aircraft. To adapt the design to needs relevant to different applications, new solutions were proposed in aerodynamic fields and materials and structural areas. Different structural solutions were reported. To optimize aircraft endurance, the innovative concept of Telescopic Tail Boom was considered along with two different tails architecture. A new structural configuration of the fuselage was proposed. Further consideration of hydrogen fuel cell electric propulsion is now being studied in collaboration between the Polytechnic of Turin and Prince Mohammad Bin Fahd University which could be the starting point of future investigations.

Full composites hydrogen fuel cells unmanned aerial vehicle with telescopic boom

Carrera, E.,Verrastro, M.,Boretti, Alberto Techno-Press 2022 Advances in aircraft and spacecraft science Vol.9 No.1

This paper discusses an improved unmanned aerial vehicle, UAV, configuration characterized by telescopic booms to optimize the flight mechanics and fuel consumption of the aircraft at various loading/flight conditions.The starting point consists of a full-composite smaller UAV which was derived by a general aviation ultralight motorized aircraft ULM. The present design, named ToBoFlex, extends the two-booms configuration to a three tons aircraft. To adapt the design to needs relevant to different applications, new solutions were proposed in aerodynamic fields and materials and structural areas. Different structural solutions were reported. To optimize aircraft endurance, the innovative concept of Telescopic Tail Boom was considered along with two different tails architecture. A new structural configuration of the fuselage was proposed. Further consideration of hydrogen fuel cell electric propulsion is now being studied in collaboration between the Polytechnic of Turin and Prince Mohammad Bin Fahd University which could be the starting point of future investigations.

Variable kinematic beam elements for electro-mechanical analysis

F. Miglioretti,E. Carrera,M. Petrolo 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.13 No.4

This paper proposes a refined electro-mechanical beam formulation. Lagrange-type polynomials areused to interpolate the unknowns over the beam cross section. Three- (L3), four- (L4), and nine-point(L9) polynomials are considered which lead to linear, bi-linear, and quadratic displacement field approximations over the beam cross-section. Finite elements are obtained by employing the principle of virtualdisplacements in conjunction with the Carrera Unified Formulation (CUF). The finite element matricesand vectors are expressed in terms of fundamental nuclei whose forms do not depend on the assumptions made. Additional refined beam models are implemented by introducing further discretizations, overthe beam cross-section. Some assessments from bibliography have been solved in order to validate theelectro-mechanical formulation. The investigations conducted show that the present formulation is ableto detect the electro-mechanical interaction. Key

Application of aerospace structural models to marine engineering

Pagani, A.,Carrera, E.,Jamshed, R. Techno-Press 2017 Advances in aircraft and spacecraft science Vol.4 No.3

The large container ships and fast patrol boats are complex marine structures. Therefore, their global mechanical behaviour has long been modeled mostly by refined beam theories. Important issues of cross section warping and bending-torsion coupling have been addressed by introducing special functions in these theories with inherent assumptions and thus compromising their robustness. The 3D solid Finite Element (FE) models, on the other hand, are accurate enough but pose high computational cost. In this work, different marine vessel structures have been analysed using the well-known Carrera Unified Formulation (CUF). According to CUF, the governing equations (and consequently the finite element arrays) are written in terms of fundamental nuclei that do not depend on the problem characteristics and the approximation order. Thus, refined models can be developed in an automatic manner. In the present work, a particular class of 1D CUF models that was initially devised for the analysis of aircraft structures has been employed for the analysis of marine structures. This class, which was called Component-Wise (CW), allows one to model complex 3D features, such as inclined hull walls, floors and girders in the form of components. Realistic ship geometries were used to demonstrate the efficacy of the CUF approach. With the same level of accuracy achieved, 1D CUF beam elements require far less number of Degrees of Freedom (DoFs) compared to a 3D solid FE solution.

Variable kinematic beam elements for electro-mechanical analysis

Miglioretti, F.,Carrera, E.,Petrolo, M. Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.13 No.4

This paper proposes a refined electro-mechanical beam formulation. Lagrange-type polynomials are used to interpolate the unknowns over the beam cross section. Three- (L3), four- (L4), and nine-point(L9) polynomials are considered which lead to linear, bi-linear, and quadratic displacement field approximations over the beam cross-section. Finite elements are obtained by employing the principle of virtual displacements in conjunction with the Carrera Unified Formulation (CUF). The finite element matrices and vectors are expressed in terms of fundamental nuclei whose forms do not depend on the assumptions made. Additional refined beam models are implemented by introducing further discretizations, over the beam cross-section. Some assessments from bibliography have been solved in order to validate the electro-mechanical formulation. The investigations conducted show that the present formulation is able to detect the electro-mechanical interaction.

Evaluation of refined theories for multilayered shells via Axiomatic/Asymptotic method

Daoud S. Mashat,E. Carrera,Ashraf M. Zenkour,Sadah A. Al Khateeb,A. Lamberti 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.11

This paper is devoted to refined shell theories for the analysis of isotropic and laminated shells. Refined theories are built by assuminghigher expansion order for the displacement field in the shell thickness directions. The implementation of these theories is made accordingto the Carrera unified formulation (CUF) which makes it possible to obtain shell governing equations in terms of fundamental nucleiwhose form is independent of the chosen theory shell. Equivalent single layer and layer wise schemes are used. The axiomatic/asymptotic technique is employed to evaluate the effectiveness of each displacement variable in the adopted displacement expansion. The error introduced by each term deactivation is evaluated with respect to a reference solution and according to a given error criterion; ifthe error computed does not exceed an a priori defined threshold the term is considered as not relevant and discarded. In this way it ispossible to construct reduced models for each stress/displacement component. Attention has been restricted to closed form Navier typesolutions and simply supported orthotropic shells are considered in the numerical investigation. Analysis of the displacement variablesrelevance is performed considering the influence of the kind of material and of the geometry, specifically isotropic and laminated materialsand thick and thin shells. “Best”' reduced models are proposed and related distributions are discussed.

Full field strain measurements of composite wing by digital image correlation

Pagani, A.,Zappino, E.,de Miguel, A.G.,Martilla, V.,Carrera, E. Techno-Press 2019 Advances in aircraft and spacecraft science Vol.6 No.1

This paper discusses the use of the Digital Image Correlation (DIC) technique for the displacement and strain measurements of a wet lay-up composite wing. As opposed to classical strain gages, DIC allows to conduct full field strain analysis of simple to complex structural parts. In this work, wing-up bending tests and measurements of the composite wing of the Dardo Aspect by CFM Air are carried out through an ad-hoc test rig and the Q-400 DIC system by Dantec Dynamics. Also, the results are used to validate a finite element model of the structure under investigation.

Analysis of landing mission phases for robotic exploration on phobos mar's moon

Stio, A.,Spinolo, P.,Carrera, E.,Augello, R. Techno-Press 2017 Advances in aircraft and spacecraft science Vol.4 No.5

Landing phase is one of the crucial and most important phases during robotic aerospace explorations. It concerns the impact of the landing module of a spacecraft on a celestial body. Risks and uncertainties of landing are mainly due to the morphology of the surface, the possible presence of rocks and other obstacles or subsidence. The present work quotes results of a computational analysis direct to investigate the stability during the landing phase of a lander on Phobos, a Mars Moon. The present study makes use of available software tools for the simulation analyses and results processing. Due to the nature of the system under consideration (i.e., large displacements and interaction between several systems), multibody simulations were performed to analyze the lander's behavior after the impact with the celestial body. The landing scenario was chosen as a result of a DOE (Design of Experiments) analysis in terms of lander velocity and position, or ground slope. In order to verify the reliability of the present multibody methodology for this particular aerospace issue, two different software tools were employed in order to emphasize two different ways to simulate the crash-box, a particular component of the system used to cushion the impact. The results show the most important frames of the simulations so as to provide a general idea about how lander behaves in its descent and some trends of the main characteristics of the system. In conclusion, the success of the approach is demonstrated by highlighting that the results (crash-box shortening trend and lander's kinetic energy) are comparable between the two tools and that the stability is ensured.

Multibody simulation and descent control of a space lander

Pagani, A.,Azzara, R.,Augello, R.,Carrera, E. Techno-Press 2020 Advances in aircraft and spacecraft science Vol.7 No.2

This paper analyzes the terminal descent phase of a space lander on a surface of a celestial body. A multibody approach is adopted to build the physical model of the lander and the surface. In this work, a legged landing gear system is considered. Opportune modelling of the landing gear crashbox is implemented in order to accurately predict the kinetic energy. To ensure the stability of the lander while impacting the ground and to reduce the contact forces that arise in this maneuver, the multibody model makes use of a co-simulation with a dedicated control system. Two types of control systems are considered; one with only position variables and the other with position and velocity variables. The results demonstrate the good reliability of modern multibody technology to incorporate control algorithms to carry out stability analysis of ground impact of space landers. Moreover, from a comparison between the two control systems adopted, it is shown how the velocity control leads to lower contact forces and fuel consumption.

Early implant placement in sites with ridge preservation or spontaneous healing: histologic, profilometric, and CBCT analyses of an exploratory RCT

Stefan P. Bienz,Edwin Ruales-Carrera,Wan-Zhen Lee,Christoph H. F. Hämmerle,Ronald E. Jung,Daniel S. Thoma 대한치주과학회 2024 Journal of Periodontal & Implant Science Vol.54 No.2

Purpose: The aim of this study was to compare changes in soft and hard tissue and the histologic composition following early implant placement in sites with alveolar ridge preservation or spontaneous healing (SH), as well as implant performance up to 1 year after crown insertion. Methods: Thirty-five patients with either intact buccal bone plates or dehiscence of up to 50% following single-tooth extraction of incisors, canines, or premolars were included in the study. They were randomly assigned to undergo one of three procedures: deproteinized bovine bone mineral with 10% collagen (DBBM-C) covered by a collagen matrix (DBBM-C/ CM), DBBM-C alone, or SH. At 8 weeks, implant placement was carried out, and cone-beam computed tomography scans and impressions were obtained for profilometric analysis. Patients were followed up after the final crown insertion and again at 1 year post-procedure. Results: Within the first 8 weeks following tooth extraction, the median height of the buccal soft tissue contour changed by −2.11 mm for the DBBM-C/CM group, −1.62 mm for the DBBM-C group, and −1.93 mm for the SH group. The corresponding height of the buccal mineralized tissue changed by −0.27 mm for the DBBM-C/CM group, −2.73 mm for the DBBM-C group, and −1.48 mm for the SH group. The median contour changes between crown insertion and 1 year were −0.19 mm in the DBBM-C/CM group, −0.09 mm in the DBBM-C group, and −0.29 mm in the SH group. Conclusions: Major vertical and horizontal ridge contour changes occurred, irrespective of the treatment modality, up to 8 weeks following tooth extraction. The DBBM-C/CM preserved more mineralized tissue throughout this period, despite a substantial reduction in the overall contour. All 3 protocols led to stable tissues for up to 1 year.