Modal Analysis

Bu lisans tezinde mokap modeli üretilmiş olan elektrikli otomobilin hızlı üretim tekniği ile prototip kaputunun yapımı için ön çalışma yapılmıştır. CAD için SolidWorks kullanılarak kaputun tasarımı, oturma yüzeyleri, bağlantı noktaları tasarlanmıştır. Tasarımı gerçekleştirilen bu parçaların üretime geçilmeden önce ANSYS programı kullanılarak sonlu elemanlar yöntemiyle mukavemet analizleri ve modal analizi gerçekleştirilmiştir. Mevcut literatür değerleri ile yapılan tasarım doğrulanmıştır. Bu analizlerden alınan sonuçlarla elde edilen gerilim ve deformasyon değerlerinin yoğunluklarına ve büyüklüklerine göre kritik bölgeler saptanmış ve doğal frekans değerleri bulunmuştur. Hızlı üretim tekniğine uygulanacak malzemeler seçilip tasarıma uygulanmış ve elde edilen analiz sonuçları çelikle üretilen literatür sonuçlarıyla kıyaslanmıştır. Uygun malzeme seçimi sonrasında kaput; stl formatına dönüştürülerek 3D yazıcı teknolojisi ile üretimi yapılıp montajı gerçekleştirilmiştir. 3D baskıyla üretileceği malzemenin yeterli dayanımı elde ettiği sonucuna ulaşılmıştır. Yapılan tasarım, analiz ve üretim için bilgisayar modelinin ön çalışması yapılmıştır.

In this paper, the complementary role of Finite Element Analysis (FEA) and Modal Analysis is studied using ANSYS Mechanical APDL. Primarily, two models (2D and 3D) of the flywheel are designed. Then, Finite Element (FE) static-stress analysis of the model was carried out, and it is found that the maximum von Mises stress (403 MPa) on the flywheel is lower than the yield stress (850 MPa) level, i.e. the design of the flywheel is safe. Afterwards, the Modal Analysis of the 3D model is carried out and six mode shapes are obtained at six different natural frequencies. Furthermore, Campbell diagram is plotted and two natural frequencies are identified. Moreover, mode shapes are plotted at the two critical speeds corresponding to their respective damped natural frequencies. The mode shapes are found to be stable, and therefore it can be remarked that the flywheel model is safe to operate within 12000 rpm. Finally, the performance of ANSYS models is determined by comparing analytical solut...

Passive means of vibration attenuation have been employed successfully and efficiently in machining systems such as turning and milling. Traditional approach to controlling vibration in a milling system is to develop control mechanisms for cutting tools or machine spindles. However, due to the nature of milling operations where the cutting tools rotate at high speed, the passive vibration control methods

In this paper a novel approach based on Asymptotic Iteration Method (AIM) is presented to solve analytically the light propagation through one-dimensional inhomogeneous slab waveguide. Practically implemented optical slab waveguides based on traditional techniques are usually inhomogeneous and numerical methods are used to obtain guided wave characteristics. In this work, we develop analytical method for modal analysis includes Eigen modes

One key failure root cause during wafer production is the electrical test by probing all interconnects of each die of the wafer. The probing process can result in excessive damage of the back end of line (BEOL) wafer layers underneath the probe pad, especially if brittle low-k dielectrics are used. The industry is trying to reduce design limitations for these under pad areas. A 3D sub-modeling simulation approach has been used to investigate stress states in layers below the probe pad. The dynamic behavior of the needle is determined by modal analysis. Its representation and calculation is done by an analytical model using the modal superposition method. These small, specialized simulation models help to distribute the simulation effort, by handling specific aspects of the real process, such as the contact problem, needle dynamics and homogenization of fine structures. The results showed that the needle dynamics can be neglected during further studies. The static load due to the max...

Aiming at the complex modal characteristic of the frame of the light electric sanitation vehicle under various working conditions, the finite element method is used to study the natural frequency and modal shape cloud diagram. Based on the frame model established in the three-dimensional software, the model characteristic is analyzed, the natural frequency and modal shape of the first five orders of mode are obtained, and their influences on vehicle travel are analyzed. The frame is improved, and the influence of the improved frame on the natural frequency and modal shape are analyzed. The results show that the bending and torsion resistance of the improved frame is ameliorated. Compared with the torsion resistance, the bending resistance of the frame is much ameliorated, which lays a foundation for the relative experiment, dynamics analysis and structural improvement of the frame.

A methodology is presented for optimizing the suspension damping and stiffness parameters of nonlinear quarter-car models subjected to random road excitation. The investigation starts with car models involving passive damping with constant or dual-rate characteristics. Then, we also examine car models where the damping coefficient of the suspension is selected so that the resulting system approximates the performance of an active suspension system with sky-hook damping. For the models with semi-active or passive dual-rate dampers, the value of the equivalent suspension damping coefficient is a function of the relative velocity of the sprung mass with respect to the wheel subsystem. As a consequence, the resulting equations of motion are strongly nonlinear. For these models, appropriate methodologies are first employed for obtaining the second moment characteristics of motions resulting from roads with a random profile. This information is next utilized in the definition of a vehicle...

For many years the problem of noise generated by trains has had an increasing importance; in this paper, attention is focused on the noise generated by the train wheels due to their vibration. Today there are many kinds of railway wheels which are affected by different noise generation mechanisms. If the traditional and well known solid wheel is considered, a lot of data is already present in the literature both concerning the vibration and the noise point of view. On the other hand, the widely used resilient wheels are not so well known in their vibratory and acoustic behaviour as in the case of solid ones. The extensive experimentation presented and commented in this paper looks for a confirmation of some literature data first, and then it gives new results. Particularly the vibro-acoustic characterization of different kinds of wheels (both solid and resilient ones) has been carried out, in order to have a comparison between the behaviour of the newly built wheels and the older ones, representing the state of the art. Besides it has been shown that a detailed modal analysis of the suspended wheel coupled to sound measurements can give useful information about the wheel noise emission in its normal operating conditions.

ÖZET Köprülerin yapisal durumu hakkindaki değerlendirmeler çoğunlukla gözleme ve proje verilerine dayali olarak yapilmaktadir. Subjektif değerlendirme ve gözlemsel metotlarin doğasinda olan sinirlamalar ile yapilan kisitli değerlendirme, bazi durumlarda yaniltici olabilmektedir. Sağlikli görünen bir köprü görünmeyen bir problem ile çok kritik durumda (örneğin bir yorulma çatlaği) ya da çok eski ve problemli görünen bir köprü yapisal olarak sağlam durumda olabilir. Ölçüme

A series of forced vibration tests are carried out in order to investigate the dynamic characteristics of a solid waste disposal incinerator building in Kashiwazaki-Kariwa Nuclear Power Plant (NPP) site, the first Steel-plate-reinforced-Concrete (SC) building in Japan, in July to August of 2004. In this study the authors attempt to investigate the fundamental dynamic characteristics of the SC building during the test focusing on: (1) evaluation of the dynamic characteristics of the SC building including soil-structure interaction effects, and (2) discussion on two system identification techniques to evaluate the dynamic characteristics of the fixed-base condition of the building by eliminating the SSI effects.

SKYCAR is a CS-23 category aircraft designed and produced by OMA SUD to be the actual sole multi-utility/multipurpose aircraft in the General Aviation High Performance Piston marketplace with an opening bonnet on fly. The out-of-standards configuration -characterized by a double vertical tail surmounted by a fully movable horizontal tail and connected to the fuselage by means of two large boomsrepresented the key-reason of a quite challenging proof of compliance to EASA requirements in terms of flutter instability. Due to the inapplicability of consolidated simplified criteria, rational analyses supported by test evidence were considered mandatory, thus demanding for a wide set of numerical and experimental activities to be performed. In this paper a general overview of such activities has been presented by pointing out the used approaches, analysis methods as well as the numerical tools implemented on their base.

The aim of this study is, in its first part, the description of the dynamic behavior of metal
plates, with the computation of natural frequencies and mode shapes; the problem has
been approached with different methods, each of them highlighting a particular
perspective.
The main points of part I are:
• The presentation of the theoretical background of the vibrating plate, to
understand the phenomenon, the main physical quantities involved, and the
mathematical equations ruling vibrations.
• An analytical computation, through equations previously demonstrated, of
natural frequencies and mode shapes for a set of different cases.
• A Finite Elements study, both for confirming the previous point, and to
provide results for cases that are too complex for the closed-form solution.
• The detailed description of the design, building and set up procedure of the
laboratory test rig to verify the model, and the discussion of the obtained
results.
• The definition of a didactic experience, to be conducted by students in the
DEXPILAB laboratories, with the relative operative procedure and safety
norms.
A practical application of this first study has been carried out in the second part of the
thesis, where it has been used to design, and build, the top soundboard of a string
instrument, a guitar, providing it with the desired acoustic properties.
In particular, this second part consists of:
• A description of the physics of the instrument, highlighting the link between the
way it is designed and built, and the dynamic properties that one should achieve.
• The modelling, through FEM, of the instrument soundboard to understand the
importance of the reinforcement ribs pattern in the dynamic behavior.
• The practical construction of a braced soundboard, tuned step by step with a
specific technique, and simultaneously analyzed with laboratory measurements.

System identification plays a crucial role in structural dynamics and vibro-acoustic system optimization. The followed approach is based on the “Modal Analysis” concept. The Eigenmodes of the system model can be visualized and allow a direct physical interpretation. Using the modal models, design improvements can be predicted and the structure optimized. The present paper not only reviews the test procedure

One of the most important dynamic analyses is modal analysis. When there is no external force on the structure, the analysis would be modal case. By using this method, we can study Natural Frequencies and Mode Shapes. This paper presents a finite element model for a simply supported rectangular plate. The study uses ABAQUS (v.6.7) software to derive the finite element model of the rectangular plate. Finally, the obtained results through FEM would be compared with an exact solution.

"La cathédrale engloutie" de Debussy is, no doubt, one work with many atractions for the musical analysis. There is the question about the tonal (or, best, modal) background, which raise also questions about modal scales, polarity and structural scheme. There is also the question about set-theory applied to a still-tonal work. And besides all this, it offers a very rich model of motivic and thematic analysis, including allusions to "entwicklende variation", all this completed with the background of the legend of the sunken city and the musical topics it deserves.

Link to full Journal "Música" nº 22: http://www.rcsmm.eu/general/files/revista/22.pdf

Modal testing is the form of vibration testing of an object whereby the natural (modal)
frequencies, modal masses, modal damping ratios and mode shapes of the object under test are
determined.
Objectives: This analysis are to identify the possible method to increase the natural frequency
of the given steel plate with dimension of (W=300mm, L=400mm, and T=1mm) under freefree
boundary conditions.
Expected Results: The outcome of this analysis would be able to increase the natural frequency
of the given plate by using basic vibration fundamentals theory and using engineering
adjustments and judgements

The crankshaft is an important part of IC engine that converts the reciprocating motion of the piston into rotary motion through the connecting rod. A crankshaft should have sufficient strength to withstand the bending and twisting moments to which it is subjected. This project describes the stress distribution of a  crankshaft for a (4-stroke, diesel engine) tractor by manual calculations for different subjected loads and moments by considering different operating conditions such as maximum bending moment condition (without twisting moment) and combined twisting and bending moment condition (where torsion is maximum).  Followed by the CAD modeling using the dimensions obtained from hand calculations. Finally, model was analyzed by using commercial Finite Element Analysis (FEA) software ANSYS™ .The stress analysis results are significant to improve the component design at the early developing stage. Harmonic analysis was used to determine the steady state response to sinusoidal (harmonic) loads of known frequency. Modal analysis was carried out to determine the natural frequencies of the crankshaft and the mode shapes were examined.