P. Chiavaroli, A. D. Martin, G. Evangelista, G. Jacazio, M. Sorli
The article deals with the architecture, performance, and experimental tests of a test bench for servo-actuators used in flight controls. After the state of the art on the subject, the innovative architecture of the built bench is described, in which flight control actuator under test and load actuator are not in line but mounted perpendicularly. The model of the bench actuating systems is then presented, consisting of the servo-controlled hydraulic actuator, load cell, speed transducer, angular position transducer of the coupling and pressure transducers. For each of these components the nonlinear multi-physics mechatronic model is described, according to the adopted solutions. The adopted force control algorithm is discussed, showing the integrative compensation on the action line and proportional-derivative on the feedback, with speed feedforward. The experimental tests carried out on the bench under stalled conditions are also presented, whose results concerning time and frequency responses are compared with those obtained through the linearized and non-linear numerical model. Finally, the non-linear models of the flight control actuator under test, controlled in position, and of the loading servo-actuator of the bench are joined together, and the results of various simulations are described.
{"title":"Real Time Loading Test Rig for Flight Control Actuators Under PHM Experimentation","authors":"P. Chiavaroli, A. D. Martin, G. Evangelista, G. Jacazio, M. Sorli","doi":"10.1115/IMECE2018-86967","DOIUrl":"https://doi.org/10.1115/IMECE2018-86967","url":null,"abstract":"The article deals with the architecture, performance, and experimental tests of a test bench for servo-actuators used in flight controls. After the state of the art on the subject, the innovative architecture of the built bench is described, in which flight control actuator under test and load actuator are not in line but mounted perpendicularly.\u0000 The model of the bench actuating systems is then presented, consisting of the servo-controlled hydraulic actuator, load cell, speed transducer, angular position transducer of the coupling and pressure transducers. For each of these components the nonlinear multi-physics mechatronic model is described, according to the adopted solutions. The adopted force control algorithm is discussed, showing the integrative compensation on the action line and proportional-derivative on the feedback, with speed feedforward.\u0000 The experimental tests carried out on the bench under stalled conditions are also presented, whose results concerning time and frequency responses are compared with those obtained through the linearized and non-linear numerical model.\u0000 Finally, the non-linear models of the flight control actuator under test, controlled in position, and of the loading servo-actuator of the bench are joined together, and the results of various simulations are described.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132744680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thermal Barrier Coatings have been widely used in modern turbine engines to protect the nickel based metal substrate from the high temperature service conditions, 1600–1800 K. In this study, some of the failure mechanisms of typical Air Plasma Sprayed Thermal Barrier Coatings (TBC) used in after-burner structures composed of three major layers: Inconel 718 substrate, NiCrAlY based metallic bond coat (BC) and Yttria Stabilized Zirconia (YSZ) based ceramic top coat (TC) are investigated. Investigation of the cracking mechanism of TBC in terms of design and performance is very important because the behavior of TBCs on ductile metallic substrates is brittle. To this end, four-point bending experiments conducted in Kütükoğlu (2015) is analyzed by using the Extended Finite Element Method (XFEM). All the analyses are conducted with the commercial finite element software ABAQUS. Three different models with varying TC and BC thicknesses are studied under four-point bending. It is observed that multiple vertical cracks are initiated in the TC. Cracks initiate at the top of YSZ and propagate through the whole TC. It is observed that the average crack spacing increases with the increasing thickness of the TC. Numerical results are found to be consistent with the experimental results. In other words, the average crack spacing for three different models are similar with the experimental results.
{"title":"Finite Element Modelling of TBC Failure Mechanisms by Using XFEM","authors":"Safa Mesut Bostancı, E. Gürses, D. Coker","doi":"10.1115/IMECE2018-86576","DOIUrl":"https://doi.org/10.1115/IMECE2018-86576","url":null,"abstract":"Thermal Barrier Coatings have been widely used in modern turbine engines to protect the nickel based metal substrate from the high temperature service conditions, 1600–1800 K. In this study, some of the failure mechanisms of typical Air Plasma Sprayed Thermal Barrier Coatings (TBC) used in after-burner structures composed of three major layers: Inconel 718 substrate, NiCrAlY based metallic bond coat (BC) and Yttria Stabilized Zirconia (YSZ) based ceramic top coat (TC) are investigated. Investigation of the cracking mechanism of TBC in terms of design and performance is very important because the behavior of TBCs on ductile metallic substrates is brittle. To this end, four-point bending experiments conducted in Kütükoğlu (2015) is analyzed by using the Extended Finite Element Method (XFEM). All the analyses are conducted with the commercial finite element software ABAQUS. Three different models with varying TC and BC thicknesses are studied under four-point bending. It is observed that multiple vertical cracks are initiated in the TC. Cracks initiate at the top of YSZ and propagate through the whole TC. It is observed that the average crack spacing increases with the increasing thickness of the TC. Numerical results are found to be consistent with the experimental results. In other words, the average crack spacing for three different models are similar with the experimental results.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122789250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The recent introduction of spike in the frontal region of high speed reentry vehicles has brought a tremendous improvement in space activities in the world. The major issue that the spikes resolves is aero heating of re-entry vehicles. Moreover, it preserves structural integrity and avoids damage. Usage of spike is economical and effective over different kinds of thermal protection system. Previous investigation on spiked re-entry vehicles leads to a conclusion that the Blunt and Snap spikes resulted in better reduction of temperature at nose of re-entry vehicle. This paper deals with geometry optimization of blunt and snap spike specifically the length, which is varied as L/8, L/4 and 3L/8 respectively where L is the length of the vehicle. ANSYS 17.2 FLUENT solver is incorporated for analysis purpose and the results are compared among the three different length spike re-entry vehicles. Modal analysis has also been carried out and natural frequency of spikes are obtained. This would provide a way to accept the safe and economical design with better thermal protection of the high-speed space vehicle.
{"title":"Recent Advancements in Spikes Used in Hypersonic Re-Entry Vehicles by Using CFD","authors":"E. Madhukar, Harish Panjagala","doi":"10.1115/IMECE2018-86550","DOIUrl":"https://doi.org/10.1115/IMECE2018-86550","url":null,"abstract":"The recent introduction of spike in the frontal region of high speed reentry vehicles has brought a tremendous improvement in space activities in the world. The major issue that the spikes resolves is aero heating of re-entry vehicles. Moreover, it preserves structural integrity and avoids damage. Usage of spike is economical and effective over different kinds of thermal protection system. Previous investigation on spiked re-entry vehicles leads to a conclusion that the Blunt and Snap spikes resulted in better reduction of temperature at nose of re-entry vehicle. This paper deals with geometry optimization of blunt and snap spike specifically the length, which is varied as L/8, L/4 and 3L/8 respectively where L is the length of the vehicle. ANSYS 17.2 FLUENT solver is incorporated for analysis purpose and the results are compared among the three different length spike re-entry vehicles. Modal analysis has also been carried out and natural frequency of spikes are obtained. This would provide a way to accept the safe and economical design with better thermal protection of the high-speed space vehicle.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126402340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Composite materials are becoming increasingly common in the aerospace industry. In order for simulation and modeling to accurately predict failure of composites, a material model based on observed damage mechanisms is required. Composites are commonly classified into four damage categories based on the composite constituents and their loading condition: fiber tension, fiber compression, matrix tension, and matrix compression. Previous work identified a compact compression (CC) specimen as a suitable option for isolating matrix compression damage. However upon continued testing, stable crack propagation in the specimen was limited to a relatively low material failure ratio (σCompressive/σTension). This paper presents specimen geometry that can isolate matrix compression damage in materials with a failure ratio greater than two, the limit of the compact compression specimens. Initial specimen selection used the compact compression specimens from previous research and added additional specimens based on commonly used compressions specimens for different materials. The added specimens included center notched compression (CNC), edge notch compression (ENC), and four-point bending (4PB). All specimens were evaluated experimentally with the success criteria of controlled propagation of a matrix compression crack. In addition to propagating a controlled matrix compression crack, specimens were required to have a visible region around the stress concentrator to allow for digital image correlation (DIC) image capture during the experiments. The specimens were manufactured from a carbon fiber reinforced polymer (CFRP) with a failure ratio greater than six. CC and 4PB specimens were unable to produce a compression crack before any other failure methods were present. CNC specimens produced an unstable compression crack that progressed from the notch to the edge of the specimen too rapidly to acquire meaningful crack propagation data. ENC specimens showed some ability to stably propagate a crack, however some tests resulted in an unstable crack propagation similar to the CNC specimens. In order to increase the test repeatability, a tapered thickness was added to the specimen around the notch tip. The resulting tapered ENC (TENC) produced repeatable controlled matrix compression crack propagation. Ultimately, the specimen fails when the crack has propagated through the entire width of the specimen. TENC specimens show promise for isolating matrix compression damage in materials with high failure ratios. Continued testing of CFRP with TENC specimens could be used to refine the material model for finite element analysis.
{"title":"Experimental Specimen for Classification of Matrix Compression Damage in Carbon Fiber Reinforced Polymers","authors":"Taylor J. Rawlings, K. Carpenter, J. Parmigiani","doi":"10.1115/IMECE2018-87132","DOIUrl":"https://doi.org/10.1115/IMECE2018-87132","url":null,"abstract":"Composite materials are becoming increasingly common in the aerospace industry. In order for simulation and modeling to accurately predict failure of composites, a material model based on observed damage mechanisms is required. Composites are commonly classified into four damage categories based on the composite constituents and their loading condition: fiber tension, fiber compression, matrix tension, and matrix compression. Previous work identified a compact compression (CC) specimen as a suitable option for isolating matrix compression damage. However upon continued testing, stable crack propagation in the specimen was limited to a relatively low material failure ratio (σCompressive/σTension). This paper presents specimen geometry that can isolate matrix compression damage in materials with a failure ratio greater than two, the limit of the compact compression specimens. Initial specimen selection used the compact compression specimens from previous research and added additional specimens based on commonly used compressions specimens for different materials. The added specimens included center notched compression (CNC), edge notch compression (ENC), and four-point bending (4PB). All specimens were evaluated experimentally with the success criteria of controlled propagation of a matrix compression crack. In addition to propagating a controlled matrix compression crack, specimens were required to have a visible region around the stress concentrator to allow for digital image correlation (DIC) image capture during the experiments. The specimens were manufactured from a carbon fiber reinforced polymer (CFRP) with a failure ratio greater than six. CC and 4PB specimens were unable to produce a compression crack before any other failure methods were present. CNC specimens produced an unstable compression crack that progressed from the notch to the edge of the specimen too rapidly to acquire meaningful crack propagation data. ENC specimens showed some ability to stably propagate a crack, however some tests resulted in an unstable crack propagation similar to the CNC specimens. In order to increase the test repeatability, a tapered thickness was added to the specimen around the notch tip. The resulting tapered ENC (TENC) produced repeatable controlled matrix compression crack propagation. Ultimately, the specimen fails when the crack has propagated through the entire width of the specimen. TENC specimens show promise for isolating matrix compression damage in materials with high failure ratios. Continued testing of CFRP with TENC specimens could be used to refine the material model for finite element analysis.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126548317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cycloidal rotors have the inherent ability to provide vectorized thrust with fast reaction times. However, their present efficiency levels restricts their routinely use as propulsion elements for air-vehicles. Efforts have been made to improve the performance of cycloidal rotors through the optimal combination of its geometric parameters. In the present work the performance improvement of cycloidal rotors is demonstrated using a different approach, namely by imposing an unsteady change on the dynamics and structure of the vortices developed around the blades. This required change on the flow field, around the blades, was applied by adding an harmonic vibration to the traditional cycloidal movement of the blades, thus causing the blades to vibrate as they describe their oscillating pitch movement. This research on the effect of harmonic vibration, on lift and drag coefficients, was done first for a single blade profile, and later for a full cycloidal rotor, and is based on the Takens reconstruction theorem and Poincaré map. Therefore, diverse test cases and conditions were considered: a single static airfoil, an oscillating blade profile, and a complete cycloidal rotor. We concluded that the optimal combination of harmonic vibration parameters, specifically; amplitude, phase angle and vibration frequency, under adequately tuned design conditions, can have a beneficial effect on cycloidal rotor performance.
{"title":"Effects of Harmonic Vibration on Cycloidal Rotor Performance","authors":"Jakson Augusto Léger Monteiro, José C. Páscoa","doi":"10.1115/IMECE2018-87103","DOIUrl":"https://doi.org/10.1115/IMECE2018-87103","url":null,"abstract":"Cycloidal rotors have the inherent ability to provide vectorized thrust with fast reaction times. However, their present efficiency levels restricts their routinely use as propulsion elements for air-vehicles. Efforts have been made to improve the performance of cycloidal rotors through the optimal combination of its geometric parameters. In the present work the performance improvement of cycloidal rotors is demonstrated using a different approach, namely by imposing an unsteady change on the dynamics and structure of the vortices developed around the blades. This required change on the flow field, around the blades, was applied by adding an harmonic vibration to the traditional cycloidal movement of the blades, thus causing the blades to vibrate as they describe their oscillating pitch movement. This research on the effect of harmonic vibration, on lift and drag coefficients, was done first for a single blade profile, and later for a full cycloidal rotor, and is based on the Takens reconstruction theorem and Poincaré map. Therefore, diverse test cases and conditions were considered: a single static airfoil, an oscillating blade profile, and a complete cycloidal rotor. We concluded that the optimal combination of harmonic vibration parameters, specifically; amplitude, phase angle and vibration frequency, under adequately tuned design conditions, can have a beneficial effect on cycloidal rotor performance.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124005828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Bertolino, Rocco Gentile, G. Jacazio, F. Marino, M. Sorli
Seals are widely used in hydraulic power systems to prevent fluid leakages. However, several types of degradation can decrease the performance of these components such as wear, which induces changes in the geometry of the cross-section area, influencing their sealing capability. Over the years, their behaviour has been primarily investigated with several theoretical and experimental researches. All these valuable results can be considered as a starting point for further investigations on the interaction between seals and the complete hydraulic equipment and on the root of seals degradation. This article proposes a physical model of performance degradation acting on dynamic seals of an electro-hydraulic servo-actuator (EHSA) ram for primary flight controls. In this article, a dynamic non-linear seals degradation model has been developed, based on the Hart-Smith hyperelasticity model, which physically describes the stress and strain of “rubber-like” materials. Similarly, wearing has been assessment by using the Archard’s equation. Furthermore, different operating temperatures have been considered to analyze the effect on seals performances. The integration between the mentioned seals degradation model and the high-fidelity model of the complete EHSA allows to evaluate the influence of various wear levels on the actuator behaviour. This research activity is inserted into a more extensive project of Prognostic and Health Management (PHM) of EHSAs. The results of the proposed simulations reveal how the performance of an EHSA can be affected by seals degradations.
{"title":"EHSA Primary Flight Controls Seals Wear Degradation Model","authors":"A. Bertolino, Rocco Gentile, G. Jacazio, F. Marino, M. Sorli","doi":"10.1115/IMECE2018-87080","DOIUrl":"https://doi.org/10.1115/IMECE2018-87080","url":null,"abstract":"Seals are widely used in hydraulic power systems to prevent fluid leakages. However, several types of degradation can decrease the performance of these components such as wear, which induces changes in the geometry of the cross-section area, influencing their sealing capability. Over the years, their behaviour has been primarily investigated with several theoretical and experimental researches. All these valuable results can be considered as a starting point for further investigations on the interaction between seals and the complete hydraulic equipment and on the root of seals degradation.\u0000 This article proposes a physical model of performance degradation acting on dynamic seals of an electro-hydraulic servo-actuator (EHSA) ram for primary flight controls. In this article, a dynamic non-linear seals degradation model has been developed, based on the Hart-Smith hyperelasticity model, which physically describes the stress and strain of “rubber-like” materials. Similarly, wearing has been assessment by using the Archard’s equation. Furthermore, different operating temperatures have been considered to analyze the effect on seals performances.\u0000 The integration between the mentioned seals degradation model and the high-fidelity model of the complete EHSA allows to evaluate the influence of various wear levels on the actuator behaviour. This research activity is inserted into a more extensive project of Prognostic and Health Management (PHM) of EHSAs. The results of the proposed simulations reveal how the performance of an EHSA can be affected by seals degradations.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115068300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Educational purposes have been the trigger for CubeSat development. Most of this class of nano-satellites where initially developed as hands-on projects at universities and institutes, mostly being of very simple construction and complexity. However, in the most recent years low cost sensors and mobile technology started to be translated into nano-satellites, and this expanded their possible mission profiles, prompting the attention of companies and government agencies. Today, many tasks that previously where only possible to be developed within a multi-million dollar/euro framework can be accomplished by nano-satellites, at a tiny fraction of their cost. One of the major weaknesses of these devices is the low level of available power onboard, and the lack of efficient state-of-the-art propulsion systems. The present paper provides a throughout discussion on the diverse propulsion technologies used for CubeSat and other micro-satellite systems. If only attitude correction is requested then, present day technologies can be readily used. However, for orbit change or interplanetary nano-spacecraft propulsion, present day technologies are not able to provide the necessary performance under the restricted power budget on-board. New routes are herein proposed for the development of thrusters for nano-satellites and other comparable size spacecrafts.
{"title":"A Review of Propulsion Systems for CubeSats","authors":"José C. Páscoa, Odelma Teixeira, Gustavo Filipe","doi":"10.1115/IMECE2018-88174","DOIUrl":"https://doi.org/10.1115/IMECE2018-88174","url":null,"abstract":"Educational purposes have been the trigger for CubeSat development. Most of this class of nano-satellites where initially developed as hands-on projects at universities and institutes, mostly being of very simple construction and complexity. However, in the most recent years low cost sensors and mobile technology started to be translated into nano-satellites, and this expanded their possible mission profiles, prompting the attention of companies and government agencies. Today, many tasks that previously where only possible to be developed within a multi-million dollar/euro framework can be accomplished by nano-satellites, at a tiny fraction of their cost. One of the major weaknesses of these devices is the low level of available power onboard, and the lack of efficient state-of-the-art propulsion systems. The present paper provides a throughout discussion on the diverse propulsion technologies used for CubeSat and other micro-satellite systems. If only attitude correction is requested then, present day technologies can be readily used. However, for orbit change or interplanetary nano-spacecraft propulsion, present day technologies are not able to provide the necessary performance under the restricted power budget on-board. New routes are herein proposed for the development of thrusters for nano-satellites and other comparable size spacecrafts.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121402743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a systematic numerical investigation of guided wave generation, propagation, interaction with damage, and reception in anisotropic piezoelectric composite plates. This approach employs piezoelectric composite materials as both load bearing and sensing elements. Finite element modal analysis of a plate unit cell with Bloch-Floquet boundary condition is performed to understand the guided wave propagation characteristics in piezoelectric composite plates. The guided wave generation and tuning characteristics are investigated using the harmonic analysis model with absorbing boundary conditions. The relationship between the generated wave modes and the laminate layup orientations is studied. Subsequently, an impact damage is introduced and modeled as a group of cone shape delaminated layers and stiffness losses within the layers through the thickness direction. 2D and 3D transient dynamic coupled-field finite element models are constructed to simulate the procedure of guided wave generation, propagation, interaction with the impact damage, and reception in an orthotropic piezoelectric composite plate using the commercial finite element software (ANSYS). In addition, Contact Acoustic Nonlinearity (CAN) is simulated via time domain transient analysis. Advanced signal processing techniques are used to extract the distinctive nonlinear features. The frequency-wavenumber analysis is further adopted to decipher wave modes and frequency components in the scattered wave field. This paper finishes with concluding remarks and suggestions for future work.
{"title":"Guided Wave Generation and Propagation in Self-Sensing Piezoelectric Composite Plates for Structural Health Monitoring","authors":"Junzhen Wang, Yanfeng Shen","doi":"10.1115/IMECE2018-86229","DOIUrl":"https://doi.org/10.1115/IMECE2018-86229","url":null,"abstract":"This paper presents a systematic numerical investigation of guided wave generation, propagation, interaction with damage, and reception in anisotropic piezoelectric composite plates. This approach employs piezoelectric composite materials as both load bearing and sensing elements. Finite element modal analysis of a plate unit cell with Bloch-Floquet boundary condition is performed to understand the guided wave propagation characteristics in piezoelectric composite plates. The guided wave generation and tuning characteristics are investigated using the harmonic analysis model with absorbing boundary conditions. The relationship between the generated wave modes and the laminate layup orientations is studied. Subsequently, an impact damage is introduced and modeled as a group of cone shape delaminated layers and stiffness losses within the layers through the thickness direction. 2D and 3D transient dynamic coupled-field finite element models are constructed to simulate the procedure of guided wave generation, propagation, interaction with the impact damage, and reception in an orthotropic piezoelectric composite plate using the commercial finite element software (ANSYS). In addition, Contact Acoustic Nonlinearity (CAN) is simulated via time domain transient analysis. Advanced signal processing techniques are used to extract the distinctive nonlinear features. The frequency-wavenumber analysis is further adopted to decipher wave modes and frequency components in the scattered wave field. This paper finishes with concluding remarks and suggestions for future work.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122388483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An important role in the design of structure is represented by the buckling analysis. The loading and service conditions, in which structures usually work, may significantly afflict their equilibrium state. This aspect often forces the design engineers to perform an accurate buckling analysis, in order to calculate critical loads of the structure. In fact, this critical load causes a sudden change of the structure, leading to a radical decrease in the loadcarrying capability. For these reasons, buckling analysis of beam-columns has been widely investigated in the past and recent years. One of the most important experimental technology to calculate the critical buckling load of structures if represented by the Vibration Correlation Technique (VCT). It allows determining equivalent boundary conditions and buckling load for several types of structures and its strength is represented by the fact that it is a non-destructive methodology: essentially, the stability loads were determined by interpolating, until singularity, the natural frequency of the structure subjected to progressive higher loadings, without reaching the instability point. VCT is already widely used for beam, plate and shell structures. This paper intends to assess a numerical simulation of the experimental data needed for the Vibration Correlation Technique. The solution proposed is developed in the domain of the Carrera Unified Formulation (CUF), according to which theories of structures can degenerate into a generalized kinematics that makes use of an arbitrary expansion of the generalized variables. Moreover, in order to reproduce results obtained in an experimental way, when large displacement and rotations may occur, geometrical nonlineatities have been taken into account. Thus, a finite element approximation is used along with a path-following method to perform nonlinear analyses. Different types of structures have been analyzed, made with metallic and composite materials, and some results are compared with others found in the VCT literature. Results show how this methodology can well evaluate the natural frequencies on the structure in a geometrical nonlinear framework, and so also the critical buckling load.
{"title":"Virtual Vibration Correlation Technique (VCT) for Nonlinear Analysis of Metallic and Composite Structures","authors":"A. Pagani, R. Augello, E. Carrera","doi":"10.1115/IMECE2018-86674","DOIUrl":"https://doi.org/10.1115/IMECE2018-86674","url":null,"abstract":"An important role in the design of structure is represented by the buckling analysis. The loading and service conditions, in which structures usually work, may significantly afflict their equilibrium state. This aspect often forces the design engineers to perform an accurate buckling analysis, in order to calculate critical loads of the structure. In fact, this critical load causes a sudden change of the structure, leading to a radical decrease in the loadcarrying capability. For these reasons, buckling analysis of beam-columns has been widely investigated in the past and recent years.\u0000 One of the most important experimental technology to calculate the critical buckling load of structures if represented by the Vibration Correlation Technique (VCT). It allows determining equivalent boundary conditions and buckling load for several types of structures and its strength is represented by the fact that it is a non-destructive methodology: essentially, the stability loads were determined by interpolating, until singularity, the natural frequency of the structure subjected to progressive higher loadings, without reaching the instability point. VCT is already widely used for beam, plate and shell structures.\u0000 This paper intends to assess a numerical simulation of the experimental data needed for the Vibration Correlation Technique. The solution proposed is developed in the domain of the Carrera Unified Formulation (CUF), according to which theories of structures can degenerate into a generalized kinematics that makes use of an arbitrary expansion of the generalized variables. Moreover, in order to reproduce results obtained in an experimental way, when large displacement and rotations may occur, geometrical nonlineatities have been taken into account. Thus, a finite element approximation is used along with a path-following method to perform nonlinear analyses.\u0000 Different types of structures have been analyzed, made with metallic and composite materials, and some results are compared with others found in the VCT literature. Results show how this methodology can well evaluate the natural frequencies on the structure in a geometrical nonlinear framework, and so also the critical buckling load.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128619834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A global-local approach has been developed for the elasto-plastic analysis of thin-walled metal structures, which interfaces between commercial finite element software and advanced structural theories based on the Carrera Unified Formulation (CUF). The structure is modeled in CUF using the Component-Wise approach where Lagrange polynomials enhance the cross-section kinematics of the beam element. The von Mises constitutive model with isotropic work hardening is used to describe the material nonlinearity. Two types of the global-local approach have been discussed: (1) elastoplasticity is considered in both global and local analyses, and (2) a linear global analysis is followed by a nonlinear local analysis. It is shown that the second version maintains the accuracy of the solution for cases where the plastic zone is localized within the structure. The described approach results in a significant reduction in the computational size of the problem, compared to standard 3D finite element analysis.
{"title":"A Global-Local Strategy for the Elastoplastic Analysis of Complex Metallic Structures via Component-Wise Approach","authors":"E. Carrera, I. Kaleel, M. Nagaraj, M. Petrolo","doi":"10.1115/IMECE2018-86564","DOIUrl":"https://doi.org/10.1115/IMECE2018-86564","url":null,"abstract":"A global-local approach has been developed for the elasto-plastic analysis of thin-walled metal structures, which interfaces between commercial finite element software and advanced structural theories based on the Carrera Unified Formulation (CUF). The structure is modeled in CUF using the Component-Wise approach where Lagrange polynomials enhance the cross-section kinematics of the beam element. The von Mises constitutive model with isotropic work hardening is used to describe the material nonlinearity. Two types of the global-local approach have been discussed: (1) elastoplasticity is considered in both global and local analyses, and (2) a linear global analysis is followed by a nonlinear local analysis. It is shown that the second version maintains the accuracy of the solution for cases where the plastic zone is localized within the structure. The described approach results in a significant reduction in the computational size of the problem, compared to standard 3D finite element analysis.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127341764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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