Дисертації з теми "Stiffened composite panel"
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Liu, Yifei. "Optimum design of a composite outer wing subject to stiffness and strength constraints." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/6833.
Повний текст джерелаZhao, Wei. "Optimal Design and Analysis of Bio-inspired, Curvilinearly Stiffened Composite Flexible Wings." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/79143.
Повний текст джерелаPh. D.
Jrad, Mohamed. "Multidisciplinary Optimization and Damage Tolerance of Stiffened Structures." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/52276.
Повний текст джерелаPh. D.
Shenoy, Sudhir Lankarani Hamid M. "Energy absorption of a car roof reinforced with a grid stiffened composite panel in the event of a rollover." Diss., Click here for available full-text of this thesis, 2006. http://library.wichita.edu/digitallibrary/etd/2006/t073.pdf.
Повний текст джерела"May 2006." Title from PDF title page (viewed on October 29, 2006). Thesis adviser: Hamid M. Lankarani. Includes bibliographic references (leaves 57-59).
Shenoy, Sudhir Shivaraya. "Energy absorption of a car roof reinforced with a grid stiffened composite panel in the event of a rollover." Thesis, Wichita State University, 2006. http://hdl.handle.net/10057/386.
Повний текст джерелаThesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
"May 2006."
Includes bibliographic references (leaves 57-59)
Cil, Kursad. "Free Flexural (or Bending) Vibrations Analysis Of Doubly Stiffened, Composite, Orthotropic And/or Isotropic Base Plates And Panels (in Aero-structural Systems)." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/2/1062256/index.pdf.
Повний текст джерелаs Solutions can be applied in that direction. Thus, the transverse shear deformations and the rotary moments of inertia of plates are included in the formulation. The very thin, yet elastic deformable adhesive layers are considered as continua with transverse normal and shear stresses. The damping effects in the plates and the adhesive layers are neglected. The sets of the systems of equations of the Mindlin Plate Theory are reduced to a set of the Governing System of First Order Ordinary Differential Equations in the state vector form. The sets of the Governing System for each Main PROBLEM constitute a Two-Point Boundary Value Problem in the y-direction which is taken along the length of the plates. Then, the system is solved by the Modified Transfer Matrix Method (with Interpolation Polynomials and/or Chebyshev Polynomials)which is a relatively semi-analytical and numerical technique. The numerical results and important parametric studies of the natural modes and the corresponding frequencies of the composite system are presented.
Cohen, David. "Calculation of skin-stiffener interface stresses in stiffened composite panels." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/82897.
Повний текст джерелаPh. D.
Grall, Bruno. "Structural analysis of geodesically stiffened composite panels with variable stiffener distribution." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12232009-020522/.
Повний текст джерелаUzman, Burak Jr. "Thermal Analysis and Response of Grid-Stiffened Composite Panels." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/31381.
Повний текст джерелаMaster of Science
Henderson, Joseph Lynn. "Combined structural and manufacturing optimization of stiffened composite panels." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-09182008-063429/.
Повний текст джерелаPhillips, John L. "Structural analysis and optimum design of geodesically stiffened composite panels." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040802/.
Повний текст джерелаNagendra, Somanath. "Optimal stacking sequence design of stiffened composite panels with cutouts." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-170635/.
Повний текст джерелаBeji, Faycel Ben Hedi. "Buckling Analysis of Composite Stiffened Panels and Shells in Aerospace Structure." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/81620.
Повний текст джерелаMaster of Science
Perry, Christine Ann. "Minimum-weight design of compressively loaded stiffened panels for postbuckling response." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-02132009-172332/.
Повний текст джерелаYoung, Richard Douglas. "Prebuckling and postbuckling behavior of stiffened composite panels with axial-shear stiffness coupling." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-144734/.
Повний текст джерелаLiu, Wenli. "Analysis and testing of composite stiffened compression panels for integrated design and manufacture." Thesis, University of Bath, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423495.
Повний текст джерелаKoundouros, Michael. "In-plane compressive behaviour of stiffened thin-skinned composite panels with a stress concentrator." Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/8375.
Повний текст джерелаElseifi, Mohamed A. "A new scheme for the optimum design of stiffened composite panels with geometric imperfections." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/29250.
Повний текст джерелаPh. D.
Bloodworth, Victoria Margaux. "Mechanisms and modelling of stringer debonding in post-buckled carbon-fibre composite stiffened panels." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/7223.
Повний текст джерелаLoup, Douglas C. "Investigation of stiffener and skin interactions for pressure loaded panels." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/50056.
Повний текст джерелаMaster of Science
incomplete_metadata
Jadhav, Prakash. "Analytical and experimental investigations of the impact response of grid-stiffened E-glass/polypropylene (PP) composite panels /." Full text available from ProQuest UM Digital Dissertations, 2005. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1276391131&SrchMode=1&sid=2&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1185301529&clientId=22256.
Повний текст джерелаFerreira, Inês Oliveira de Vasconcelos. "Analysis of the structural behaviour of stiffened panels subjected to compressive loading conditions." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/16557.
Повний текст джерелаStiffened panels form the basic structural building blocks of airplanes, vessels and other structures with high requirements of strength-to-weight ratio. As a consequence it is crucial to understand the behaviour of these type of panels. Since buckling is the primary mode of failure of stiffened panels, it will be the focus in the present work. In the present work it was carried out several analysis, using the simulation software Abaqus, in order to study the buckling and postbuckling behaviour. Two different panels were tested in this thesis, the first one an aluminium stiffened panel, which its main goal was to understand the methodologies involved in the analysis of the buckling behaviour, and the second one a composite stiffened which its main goal was to find the proper tools to simulate its behaviour. Therefore, two different methods were used, the Riks method was used to analyse the aluminium panel and the Stabilize method to analyse the composite panel. The behaviour of stiffened panels are influenced by several parameters such as, the number and type of elements, the skin-stringer connection, the boundary conditions, the magnitude of imperfections, etc. So in the present work, those parameters were taken into account and its influence will be shown.
Os painéis reforçados formam as estruturas básicas de construção de aviões, navios e outras estruturas que exijam uma elevada relação entre resistência e peso. Deste modo, é crucial perceber o comportamento deste tipo de painéis. Tendo em conta que a encurvadura é o modo principal de falha deste tipo de painéis, será o foco de estudo desta dissertação. No trabalho presente, foram realizadas várias análises de forma a estudar o comportamento de encurvadura e pós-encurvadura de painéis reforçados, utilizando para isso o software de simulação Abaqus. Foram testados dois painéis diferentes, sendo que o primeiro foi um painél de alumínio, com o objectivo de perceber as metodologias envolvidas na simulação de placas reforçadas, e o segundo, um painel compósito, com o objecto de encontrar as ferramentas adequadas para simular o seu comportamento. Para isso, dois métodos distintos foram utilizados, sendo que foi utilizado o método de Riks para analisar a placa de alumínio e para analisar a placa compósita foi ultizado o método de estabilização. O comportamento dos painéis reforçados é influênciado por vários parâmetros tais como, modelo numérico, ligação entre placa e reforço, condições de fronteira, magnitude de imperfeições, etc. Assim, todos esses parâmetros foram tidos em conta e a sua influência irá ser mostrada no trabalho presente.
Javanshir, Hasbestan Jaber. "Free Flexural (or Bending) Vibration Analysis Of Certain Of Stiffened Composite Plates Or Panels In Flight Vehicle Structures." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12611489/index.pdf.
Повний текст джерелаFree Flexural (or Bending) Vibrations of Stiffened Plates or Panels&rdquo
are investigated in detail. Two different Groups of &ldquo
Stiffened Plates&rdquo
will be considered. In the first group, the &ldquo
Type 4&rdquo
and the &ldquo
Type 6&rdquo
of &ldquo
Group I&rdquo
of the &ldquo
Integrally-Stiffened and/or Stepped-Thickness Plate or Panel Systems&rdquo
are theoretically analyzed and numerically solved by making use of the &ldquo
Mindlin Plate Theory&rdquo
. Here, the natural frequencies and the corresponding mode shapes, up to the sixth mode, are obtained for each &ldquo
Dynamic System&rdquo
. Some important parametric studies are also presented for each case. In the second group, the &ldquo
Class 2&rdquo
and the &ldquo
Class 3&rdquo
of the &ldquo
Bonded and Stiffened Plate or Panel Systems&rdquo
are also analyzed and solved in terms of the natural frequencies with their corresponding mode shapes. In this case, the &ldquo
Plate Assembly&rdquo
is constructed by bonding &ldquo
Stiffening Plate Strips&rdquo
to a &ldquo
Base Plate or Panel&rdquo
by dissimilar relatively thin adhesive layers. This is done with the purpose of reinforcing the &ldquo
Base Plate or Panel&rdquo
by these &ldquo
Stiffening Strips&rdquo
in the appropriate locations, so that the &ldquo
Base Plate or Panel&rdquo
will exhibit satisfactory dynamic response. The forementioned &ldquo
Bonded and Stiffened Systems&rdquo
may also be used to repair a damaged (or rather cracked) &ldquo
Base Plate or Panel&rdquo
. Here in the analysis, the &ldquo
Base Plate or Panel&rdquo
, the &ldquo
Stiffening Plate Strips&rdquo
as well as the in- between &ldquo
adhesive layers&rdquo
are assumed to be linearly elastic continua. They are assumed to be dissimilar &ldquo
Orthotropic Mindlin Plates&rdquo
. Therefore, the effects of shear deformations and rotary moments of inertia are considered in the theoretical formulation. In each case of the &ldquo
Group I&rdquo
and &ldquo
Group II&rdquo
problems, the &ldquo
Governing System of Dynamic Equations&rdquo
for every problem is reduced to the &ldquo
First Order Ordinary Differential Equations&rdquo
. In other words the &ldquo
Free Vibrations Problem&rdquo
, in both cases, is an &ldquo
Initial and Boundary Value Problem&rdquo
is reduced to a &ldquo
Two- Point or Multi-Point Boundary Value Problem&rdquo
by using the present &ldquo
Solution Technique&rdquo
. For this purpose, these &ldquo
Governing Equations&rdquo
are expressed in &ldquo
compact forms&rdquo
or &ldquo
state vector&rdquo
forms. These equations are numerically integrated by the so-called &ldquo
Modified Transfer Matrix Method (MTMM) (with Interpolation Polynomials)&rdquo
. In the numerical results, the mode shapes together with their corresponding non-dimensional natural frequencies are presented up to the sixth mode and for various sets of &ldquo
Boundary Conditions&rdquo
for each structural &ldquo
System&rdquo
. The effects of several important parameters on the natural frequencies of the aforementioned &ldquo
Systems&rdquo
are also investigated and are graphically presented for each &ldquo
Stiffened and Stiffened and Bonded Plate or Panel System&rdquo
. Additionally, in the case of the &ldquo
Bonded and Stiffened System&rdquo
, the significant effects of the &ldquo
adhesive material properties&rdquo
(i.e. the &ldquo
Hard&rdquo
adhesive and the &ldquo
Soft&rdquo
adhesive cases) on the dynamic response of the &ldquo
plate assembly&rdquo
are also presented.
Bertolini, Julien. "Contribution à l'analyse expérimentale et théorique des ruptures de structures composites en post-flambement par décollement de raidisseurs." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/207/.
Повний текст джерелаFor composite fuselage applications, stringers will be bonded to the skin. The aim of this work is to study skin to stringers attachments in order to ensure load transfers mainly during post-buckling phases and taking into account environmental effects and fatigue. Firstly, a test campaign was launched on "skin/stringer flanges". Influences of temperature, ageing and fatigue behaviour have been studied. Numerical models adapted to industrial requirements have been set up and allow a good correlation between tests and calculations in fatigue and static. Secondly, three and four points bending tests on "skin/full stringers" assemblies were performed and demonstrated the particularities of omega stringers and the influence of resin fillets linked to the manufacturing process. Furthermore, specific seven points bending tests show effects of biaxial bending observed during post-buckling phases. For all the tests performed, numerical studies allow the validation of the debonding criterion previously developed and a global/local approach is proposed at structural level. Finally, two stiffened panels were tested in compression and shear. The post-buckling behaviour is studied and allows the validation of the methods developed during the study and provides the main conclusions
Ungwattanapanit, Tanut [Verfasser], Horst [Akademischer Betreuer] Baier, Horst [Gutachter] Baier, and Kai-Uwe [Gutachter] Bletzinger. "Optimization of Steered-Fibers Composite Stiffened Panels including Postbuckling Constraints handled via Equivalent Static Loads / Tanut Ungwattanapanit ; Gutachter: Horst Baier, Kai-Uwe Bletzinger ; Betreuer: Horst Baier." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1152384082/34.
Повний текст джерелаBadalló, i. Cañellas Pere. "Analysis and optimization of composite stringers." Doctoral thesis, Universitat de Girona, 2015. http://hdl.handle.net/10803/323087.
Повний текст джерелаL'ús de panells rigiditzats a la indústria aeronàutica i aeroespacial ha anat creixent les darreres dècades. Per altra banda, el creixement exponencial de l'ús dels materials compòsits en els últims anys també ha tingut una forta incidència en aquests components estructurals i en la indústria en general. Aquest nous materials fan aparèixer comportaments desconeguts fins al moment, com per exemple l'aparició de nous mecanismes de fallada. Aquests fets provoquen que el càlcul, anàlisi i assaig d'estructures de material compòsit sigui complex. Per aquest motiu, sumat a l'augment de potència de càlcul dels ordinadors, l'assaig virtual amb el mètode dels elements finits ha anat agafant una importància cabdal en el càlcul de components d'alta responsabilitat estructural. De la mateixa manera, l'intent de millorar els panells rigiditzats ha portat a utilitzar mètodes d'optimització. Modificant diferents paràmetres es busca dissenyar panells rigiditzats per realitzar una tasca desitjada de manera òptima
Lin, Chung-Yi. "Determination of the fracture parameters in a stiffened composite panel." 2000. http://www.lib.ncsu.edu/etd/public/etd-363110221010033260/etd.pdf.
Повний текст джерелаLee, Tung Ying, and 李東穎. "Optimal Design of Stiffened Composite Flat-Panel Speakers by Nano-Carbon Tube." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/10364187681701278249.
Повний текст джерела大葉大學
工業工程與科技管理學系
94
The main object of this research was constructed a Stiffened Composite Flat-Panel Speaker of Nano-Carbon Tub and utilized the heuristic algorithms to smooth Sound Pressure Level (SPL) curves by different design parameters. The panel speaker was developed by computer aided engineering, optimization design, measuring and making. The composite panel , spring system and exciting panel was discussed in this investigation. Besides, the model of speaker was simulated by the commercial finite element package, ANSYS. The volume of speaker was defined in 30mm*18mm*7mm, and the frequency was during 300 to 20000Hz. The goal value of SPL was defined as the first nature frequency over 75dB and the mediant valley below 6dB. The average value of SPL during 10000 to 20000Hz was over 70dB. The distance between speaker and the SPL receiver was 30cm. It is shown that the heuristic algorithms can achieve the target efficiently.
Huang, Liang. "Innovative multi-level methodology incorporating the techniques of finite element modelling and multimodal optimization for concept design of advanced grid stiffened composite panels against buckling." Thesis, 2015. http://hdl.handle.net/2440/98727.
Повний текст джерелаThesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2015
Hsu, Ya-Chu, and 許亞筑. "Optimization Design of Stiffened Composite Panels." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/03271938262377310132.
Повний текст джерела國立雲林科技大學
機械工程系
102
In the optimization of fiber angles for composite laminates, the fiber angles of some layers have major effects on the objective, while some just have minor effects. To solve this problem, a genetic algorithm with the function of elite comparison is proposed in this study. Also in this algorithm the unnecessary repeat execution of the finite element analysis is avoided. In order to validate this proposed algorithm, several examples are investigated to have comparison with the results from the literature. For example, the fiber angle optimization to fit the known frequencies、maximization of the fundamental frequency of laminated composites、the fiber angle optimization for composite laminated with a central hole suffered uniaxial load, etc. The results indicate that the proposed algorithm can accelerate the convergence speed and improve the accuracy of the results. In order to explore the fiber angle for the stringer-stiffened composite panel to resist buckling, the problem is divided into two types. One type has the same fiber angle for both the skin and the stinger, and they are the design variables. Form the results ,although the error of one type 128 training group is more than 200 training, but the result that predict the angle is equal. In the other problem, the fiber angle of the skin is fixed, while the fiber angles of the stringer are set as the design variables. That can find maximum buckling load. To save the calculation time of finite element analysis, a back-propagation neural network is established and used with the proposed genetic algorithm to search the optimal solution.
ZHANG, YI-ZHENG, and 張宜正. "Random vibration of stiffened composite panels." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/50112611712780449178.
Повний текст джерелаPeng, Kuo-Chin, and 彭國晉. "Sound Radiation Analysis of Stiffened Composite Panels." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/6gz5q9.
Повний текст джерела國立交通大學
機械工程系所
92
The effects on sound radiation of composite panels with different stiffened designs are studied in this thesis. This study is used to design the stiffened composite panels with enough stiffness which can avoid the fluctuation of sound pressure. By investigating the differences among the behaviors of sound pressure responses of four types of stiffened plates and an unstiffened one, we obtain a structural design which can effectively modify the stiffness of a plate structure and its sound radiation behavior. For theoretical analysis, the simulation models of radiating panels with different designs of stiffeners were constructed using the software ANSYS. The amplitudes and the phases of these panels were obtained from the analyses of the simulation models using given system parameters such as spring constants of suspension and damper, the thrust of the voice coil and the damping ratio of the loudspeaker system, which were measured from experiments. Then, we use the amplitudes and the phases in the program of calculation of sound pressure level to simulate the behaviors of sound radiation of the loudspeakers. Through the comparison between the curves of sound pressure response measured by the sound measurement system MLSSA and the ones simulated by computer, we can find out the reason causing the drops in sound pressure curves and the direction to improve the loudspeaker system further. Finally, the discrepancies between the results of experiment and these of simulation were discussed.
Yu, Cheng-Lin, and 游政霖. "Optimum Design of Stiffened Composite Sound Radiating Panels." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/23164245072847733845.
Повний текст джерела國立交通大學
機械工程系所
96
Optimum Design of Stiffened Composite Sound Radiating Panels Student : Cheng-Lin Yu Advisor : Dr. Tai-Yan Kam Department of Mechanical Engineering National Chiao Tung University ABSTRACT In this thesis, the first part studies the effects of elastic suspensions and panel rigidity on the sound pressure level (SPL) curves of composite sound radiating panels. The SPL curves measured by the used of wave-type suspensions and L-type suspensions in loudspeakers have shown that these effects are minimal. But, the effects of panel rigidity are too significant to be neglected. In order to improve the smoothness of SPL curve, composite stiffeners are added to the radiating plate to suppress the mid-frequency dip of the SPL curve. In the theoretical study, some mode shapes of the radiating plate that may have adverse influences on the sound radiation in certain frequency ranges are determined using a verified ANSYS FEA model. An optimal design method is proposed to determine the dimensions of the stiffeners for different stiffening patterns. For each stiffening pattern, the optimal stiffener sizes are determined to suppress the detrimental modes which are harmful to sound radiation and make the SPL curve smoother and the speaker possess higher sensitivity. Experiments are performed to verify the feasibility of the proposed design of the loudspeaker.
Badalló, Cañellas Pere. "Virtual test of stiffened panels of composite materials under compression load." Master's thesis, 2009. http://hdl.handle.net/10216/58083.
Повний текст джерелаBadalló, Cañellas Pere. "Virtual test of stiffened panels of composite materials under compression load." Dissertação, 2009. http://hdl.handle.net/10216/58083.
Повний текст джерелаChang, Jun-wei, and 張竣惟. "Vibration and Sound Radiation of Rectangangular Composite Panels stiffened at Different Location." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/31092538227289440062.
Повний текст джерела國立交通大學
機械工程學系
100
This paper is focused on the sound radiation behavior of stiffened sound radiation panels for flat-panel loudspeaker. If the sound radiation panel is not properly design, it is easy for a flat-panel speaker to have a significant sound pressure drop in the mid-frequency range, which may affect the sound quality of the speaker. To suppress or even eliminate the sound pressure drop, this thesis attempts to enhance the rigidity of the plate by using an appropriate stiffening method. There are two parts in this thesis. In the first part, a Rayleigh-Ritz Method is constructed to analyze the sound radiation behavior of stiffened sound radiation panels. The results obtained using the proposed Rayleigh-Ritz Method are compared with those obtained from the finite element software ANSYS. It has been shown that the natural frequencies and the sound pressure level (SPL) curves produced by the proposed method are in good agreement with those produced by ANSYS or experiments. In the second part, ANSYS is used to find the appropriate stiffening pattern for designing the sound radiation panel and the ideal material constants of the panel so that the major sound pressure drop in the mid-frequency range can be suppressed.
Attallah, K. M. Z., J. Ye, and Dennis Lam. "Three-Dimensional Finite Strip Analysis of Laminated Stiffened Panels." 2007. http://hdl.handle.net/10454/5566.
Повний текст джерелаIn this paper, a new three-dimensional spline finite strip method (spline FSM) is introduced. This is done by combining the classical spline finite strip method [1] and the state space approach. According to the traditional spline FSM, a laminated plate is divided into strips. Within each strip, the spline FSM calls for the use of simple polynomials and a continuously differentiable spline function, respectively, in the transverse and in-plane directions. In the through-thickness direction, the state space method is used to compute the distribution of displacements and stresses. The combination of the in-plane spline FSM and the out-of-plane state space formulations results in a global state space equation that is solved numerically by the precise time step integration method [2,3]. Apart from obtaining a three-dimensional solution, the new method has a unique feature that the final algebra equation system is independent of the number of material layers of a laminate. The main aim of this work is to establish the new solution procedure and validate the method. To this end, the work reported in the paper focus on laminated plates with arbitrary boundary conditions. Thus, the spline FSM is more flexible than the FSM in imposing boundary conditions. Future development is expected to extend the solution to more practical applications. From the numerical validation included, it can be seen clearly that the newly developed method can provide accurate three dimensional solutions for laminated composites, particularly, with continuous transverse stress distributions across material interfaces. This is normally difficult to obtain if a traditional three dimensional finite element is used, where only continuity of displacements across material boundaries are guaranteed. Apart from the above new feature, the new three-dimensional formulation always ends up with a global matrix whose dimension depends only on the number of strips and knots that a plate has been divided into, and is completely independent of the number of material layers of the plate.
"Damage Detection in Blade-Stiffened Anisotropic Composite Panels Using Lamb Wave Mode Conversions." Master's thesis, 2012. http://hdl.handle.net/2286/R.I.14856.
Повний текст джерелаDissertation/Thesis
M.S. Aerospace Engineering 2012
Wang, Yi-Ting, and 王怡婷. "Optimal Design and Manufacture of Double Flat-Panel Speakers Stiffened by Nano-Carbon Tube Composites." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/38771876706349448432.
Повний текст джерела大葉大學
工業工程與科技管理學系
98
The main object of this paper is designed and developed a double flat-panel speaker stiffened by nano-carbon tube composites which it had thin thicknesses, broad frequency and acoustic fidelity vigorous not distorted it. Two types of vibrating plate, namely, a high audio speaker and medium-low audio speaker constructed on the basis of the manufacture technique and sound pressure theory are developed for the design and analysis of double flat-panels. The study is analyzed the frequency and sound pressure value of double flat-panel speakers with different design parameters such as stiffness and weight of composite panels, boundary condition and spring constant of suspension system and vibration area which are constructed using a finite element constructed on the basis of the software ANSYS. The double flat-panel speakers can be applied to the general plane video and music electronic products loudspeaker system, achieves nowadays pursues the monitor more and more thin tendency. The double rectangular flat-panel speaker can be used in dual-channel flat-panel speakers for portable DVD players and notebook computers ... and other products. According to developed the analytical method of a set of simulation and optimal design is proceed to optimal design of multiple objective function for stiffened composite double flat-panels in 100Hz~20KHz frequency zones. The 100Hz~20KHz frequency zones had divide into 4 zones, every zones variable values multiply by weight was the sum that was the objective function of multiple optimal design. In the limit small thrust of low power, is used the optimal method to find the best manufacturing parameters (includes the lengths of flat-panel speaker, spring constant of suspension system, stiffened types and vibration lengths) made the sound pressure value curve had smooth and get the best sound pressure value. Therefore, the optimal manufacturing parameters would manufacture double flat-panels to measured sound pressure curve that compared experimental values and theory values.
Lee, Shih-Feng, and 李士豐. "Optimal Design and Manufacture of Miniature Flat-Panel Speakers Stiffened by Nano-Carbon Tube Composites." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/86214776163984623148.
Повний текст джерела大葉大學
工業工程與科技管理學系
95
The main object of this paper is developed a miniature flat-panel speakers stiffened by nano-carbon tube composites which are low frequency sound quality, smooth curve of sound pressure, and reduce the decay rate of high frequency sounds. The several standard of flat-panel speakers stiffened including the 30mm×18mm×7mm、40mm×14mm×7mm and 50mm×14mm×7mm. The paper is used the ANSYS software to solved the sound curve in flat-panel speakers stiffened and used optimal theory to solved optimal manufacture parameters (including the thickness ratio of flat-panel speaker and nano-carbon tubes that in the same weight, boundary condition and spring constant of suspension system, vibration area and location) which make the sound pressure value curve is smooth in global frequency. The flat-panel speakers stiffened which is developed by this project can reach the goals of economize electric power, maximum bearing, the low-frequency had powerful voices and the high-frequency had a better clarity. According to the best results of manufacture parameters, the materials and molds of suspension system are choused to manufacture suspension systems and fabricate miniature flat-panel speakers stiffened. The experimental and optimal methods are presented to study the optimal sound pressure curve of flat-panel speaker. The optimal methods proved to be accuracy.
Σταματέλος, Δημήτριος. "Μεθοδολογία ανάλυσης και προκαταρκτικού σχεδιασμού μη-συμβατικών αεροναυπηγικών δομών". Thesis, 2010. http://nemertes.lis.upatras.gr/jspui/handle/10889/4301.
Повний текст джерелаThe design and development of a modern aerospace structure consists of many design stages. The most important stages are the conceptual and the preliminary where the initial sizing of the structure is obtained. It is known that the conventional design of the aircraft’s main structural members has reached a high optimization level, where margins for further improvement are small. The current demands of the lightweight structures such as weight reduction, payload increase etc. have led the aerospace industries develop unconventional structures and partially substitute the metallic materials of the primary structures with composites. The current trend of designing and evolving unconventional aerospace structures, without performing extended experimental tests, leads to the development of behavior models. The simulation of the experimental tests (through the behavior models) is achieved using high performance computers and numerical methods (Finite Element Method, Boundary Element Method etc). To apply simulation methods during the conceptual and preliminary stage is not an easy task. Most of the difficulties are the numerous geometrical, material parameters and the structural details that alter during the iterative process of the design. So, the exclusive usage of numerical analysis methods becomes very time consuming, if it is not accompanied by analytical or semi analytical methods of the sub-problems of the design. Part of the preliminary design of an unconventional wing structure is to prevent upper skin from failure. The stiffened panels that comprise the upper skin of the wing suffer from buckling due to the applied compressive loads. The sizing of the composite stiffened panels usually requires numerous of iterative calculations for various geometries, loading and boundary conditions etc. The examination of each case separately, with the use of numerical methods, results to time consuming analyses of the entire structure. Therefore, the development of appropriate analytical or semi analytical methods for estimating stiffened panels’ critical buckling load is of great importance. For this purpose, in the present thesis, analytical and semi analytical methodologies are developed for estimating the critical buckling load of stiffened panels. The developed methodologies are incorporated as design criteria in the sizing routine of the entire structure. The sizing routine comprises additional sizing criteria for checking the strength of wing’s structural members at each phase of the iterative process. Applying the developed sizing routine in various wing configurations made of composite materials, multispar wing designs are studied. Specifically, analytical and semi analytical methods for global and local buckling problems of stiffened panels are developed. The methodology of global buckling problems is based on the mathematical conversion of a stiffened panel to an equivalent homogeneous panel. The developed method of homogenization of stiffened panels appears to have significant advantages over the already existed homogenization methods. Additionally, the energy method Rayleigh-Ritz is applied for solving global buckling problems of stiffened panels with partial anisotropy considering discrete stiffeners. Regarding local buckling problems of stiffened panels, a new methodology is developed for estimating the critical local buckling load with the use of energy methods. The approach considers the stiffened panel segment located between two stiffeners, while the remaining panel is replaced by equivalent transverse and rotational springs of varying stiffness, which act as elastic edge supports. The buckling analysis of the segment provides an accurate and conservative prediction of the panel local buckling behavior. Consequently, the developed methodology is extended in the prediction of post-buckling response of stiffened panels where skin has undergone local buckling. The developed methodologies for calculating the critical buckling load are applied for sizing the wing members of an unconventional wing (multispar configuration) from composite materials. An efficient methodology based on fast Finite Element (FE) stress analysis combined to analytically formulated design criteria is presented for the initial sizing of a large scale composite component. A detailed comparison between optimized designs of conventional (2-spar) and three alternative wing configurations which comprise 4-, 5-, and 6-spars for the wing construction is performed. In order to understand the effect of different material properties, as well as the variation of maximum strain level allowed in the total wing mass, parametric analyses are performed for all wing configurations considered. It arises that under certain conditions the multispar configuration demonstrates significant advantages over the conventional design. This would lead to a mass reduction of 12%.