Dynamic analysis of rocket motor case

<p>This work presents a numerical and analytical vibrational and structural analysis of a wing model with morphing winglets. The methodology for this analysis is developed by the undergraduate thesis students in collaboration with the faculty at Toronto Metropolitan University (formerly known as Ryerson University) and performs a static structural and modal analysis for the developed wing with morphing winglet model. This report summarizes the modal and static structural analysis conducted on the model. The CAD model for the study was developed on Solidworks while the two analyses were conducted on Ansys. The wing model was developed with four winglet configurations with varying cant angles. Various winglet configurations were designed with variable cant to study the effect of morphing winglet on the structure’s modal analysis. During the structural test, it was observed that the model undergoes a deflection of 0.001 in under the prescribed loading conditions. The modal analysis was completed for the four configurations using similar boundary conditions as for the static structural analysis. The average frequency for the first mode shape for all the configurations were recorded to be 29 Hz.</p> <p>The results for the modal analysis conducted on Ansys were then verified using an analytical methodology. The equations for this method were developed by modelling the wing as a slender and straight wing with rigid root and no sweep back angles. The procedure for this accounted for the maximum speed of the wind tunnel at Toronto Metropolitan University. The frequency solution obtained from the analytical methodology was then compared to the frequency obtained from the modal analysis completed on Ansys. The frequency at flutter was calculated to be 30 Hz. This validates the assumptions and expectations made prior to both methods of analysis.</p> <p>The next step for this study would be to build the 3D model of the wing with morphing winglets and conduct a ground vibration testing and wind tunnel testing. The observations made during this study, specifically, the natural frequencies, damping, and mode shapes, can be further compared and validated through conducting the ground vibration testing and wind tunnel testing of these models. By comparing the results, it is possible to validate the numerical models and simulation techniques used for the modal analysis and improve the design of the wing with winglets.</p>

Lightweight and high strength composite materials are vital for unmanned aerial vehicles (UAVs) and aerospace technologies with desired characteristics. Carbon composite materials exhibit extraordinary properties for UAVs and aerospace applications. This study aimed to discover the best-prepared composition of composites material having epoxy LY-5052 and carbon fibres laminate for UAVs. Besides, to develop a low cost with high specific strength composite material for aerospace application to replace metallic alloys. In this work, the vacuum bag technique is used to prepare rectangular strips of three different ratios of carbon fibre/epoxy laminates [(40:60), (50:50) and (60:40)] to obtain the best composite in terms of properties. The thermo-mechanical and viscoelastic behaviour of composite materials were evaluated using differential scanning calorimetry (DSC), universal testing machine (UTM) and dynamic mechanical analysis (DMA). The tensile strength of epoxy LY5052 composites with 60 wt% has enhanced to 986%, and glass transition temperature (Tg) was improved from 71oC to 110oC. Overall, 60 wt% carbon fibre exhibits better thermo-mechanical properties with lightweight, which may be a future composite material for aerospace, especially UAVs technologies.

Analysis of dynamic characteristic was conducted focusing on the transportation of high-pressure storage tanks, covering two scenarios: independent transportation and mixed transportation. For independent transportation, analysis of free modal was carried out to obtain the first four orders of modal shapes. Additionally, the influence of two constraint methods on the modal characteristics and stress distribution was studied, including fixed at both ends and fixed at the cylinder body. Results show that when the tank was fixed at the cylinder body, it had a higher natural frequency and a lower stress level, making it safer. For mixed transportation, a finite element model was built for 6 high-pressure storage tanks, and analysis of random vibration was performed. The results showed that stress was mainly concentrated on the crossbeams and connection nodes, while the stress on the main body of the storage tanks was relatively low. The overall structure exhibited excellent fatigue performance and met the mechanical and safety requirements under random vibration conditions.

The stability of the two-dimensional wake behind a circular cylinder - a free flow of general interest in differing applications (from aerodynamics to environmental physics and biology) - is studied by means of two different but complementary theoretical methods. The first part of the work is focused on the asymptotic evolution of disturbances described through modal analysis, a method which allows the determination of the asymptotic stability of a flow. The stability of the intermediate and far near-parallel wake is studied by means of a multiscale approach. The disturbance is defined as the local wavenumber at order zero in the longitudinal direction and is associated to a classical spatio-temporal WKBJ analysis. The inverse of the Reynolds number is taken as the small parameter for the multiscaling. It takes into account non-parallelism effects related to the transversal dynamics of the base flow. The first order corrections find absolute instability pockets in the first part of the intermediate wake (and not in the near wake, where the recirculating eddies are, as usually seen in literature in contrast with the near-parallelism hypothesis). These regions are present for Reynolds numbers larger than $Re=35$. That is in agreement with the general notion of critical Reynolds number for the onset of the first instability of about $Re=47$. In particular, for Re=50 and Re=100, the angular frequency obtained is in agreement with global data in literature concerning numerical and experimental results. The instability is convective throughout the domain. All the stability characteristics are vanishing in the far field, a fact that is independently confirmed by the asymptotic analysis of the Orr-Sommerfeld operator. Using asymptotic Navier-Stokes expansions for the wake inner field the entrainment evolution in the intermediate and far domain is evaluated in terms of asymptotic expansion. The maximum of entrainment is reached in the region where the absolute instability pockets are found. Downstream of this region the entrainment is decreasing and eventually vanishing in the far wake. This point confirms the validity of the multiscale approach. In the second part of the thesis the stability analysis is studied as an initial-value problem to observe the transient behaviour and the asymptotic state of perturbations initially imposed. The initial-value problem allows the formulation to be extended to the near-parallel flow configuration. The initial-value method is, however, less general than the modal analysis, since many parameters, such as the polar wavenumber, the spatial damping rate, the angle of obliquity and the symmetry of the perturbation, are involved. An exploratory analysis of these parameters permits the study of different transient configurations. Before the asymptotic (stable or unstable) state is reached, maxima and minima of the perturbation energy are observed for transients lasting hundreds of time scales. In the temporal asymptotics, the initial-value problem well reproduces modal results in terms of angular frequency and temporal growth rate. Moreover, for Reynolds numbers larger than the critical one (Re_{cr} = 47), the present method gives a good prediction, in terms of wavelength and pulsation, of the vortex shedding observed in experiments. In the framework of the initial-value problem formulation, a multiscale analysis for the stability of long waves is then proposed. Even to the lowest order, the multiscaling - whose small parameter is defined as the polar wavenumber - approximates sufficiently well the full problem solution with a relevant reduction of the computational cost. The two (modal and non-modal) analyses combined together lead to a quite complete description of the bluff-body wake stability

A domain-decomposition method to implement electrostatic free boundary conditions in the radial direction for electric discharges

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation A. Imthiyas, Samuvel Michael B., Naveen R., M. Arun Murugan, Mukesh Dinesh; Analysis of conventional and composite leaf spring using ANSYS. AIP Conference Proceedings 30 January 2023; 2523 (1): 020166. https://doi.org/10.1063/5.0112445 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

Investigation of effective coating of the Ti–6Al–4V alloy and 316L stainless steel with graphene or carbon nanotubes with finite element methods

Static and modal analyses of structures with different repeated patterns

In this paper a semi-analytical method is introduced to calculate the high frequency electromagnetic force and vibration in electrical machines. Firstly, an efficient field reconstruction (FR) technique is utilized to calculate the high frequency magnetic field and force harmonics which are excited by current harmonics, such as the PWM side-band current harmonics in inverter fed machines. Then, the structural transfer function of the machine structure is obtained by static structural analysis and modal analysis. Thereafter, the vibration caused by high frequency current harmonics can be computed instantly by mode superposition. The proposed method is verified by the experiment results at the end of this paper.

An integrated structural optimization strategy was produced in this study for direct-drive electrical generator structures of offshore wind turbines, implementing a design for an additive manufacturing approach, and using generative design techniques. Direct-drive configurations are widely implemented on offshore wind energy systems due to their high efficiency, reliability, and structural simplicity. However, the greatest challenge associated with these types of machines is the structural optimization of the electrical generator due to the demanding operating conditions. An integrated structural optimization strategy was developed to assess a 100-kW permanent magnet direct-drive generator structure. Generated topologies were evaluated by performing finite element analyses and a metal additive manufacturing process simulation. This novel approach assembles a vast amount of structural information to produce a fit-for-purpose, adaptative, optimization strategy, combining data from static structural analyses, modal analyses, and manufacturing analyses to automatically generate an efficient model through a generative iterative process. The results obtained in this study demonstrate the importance of developing an integrated structural optimization strategy at an early phase of a large-scale project. By considering the typical working condition loads and the machine’s dynamic behavior through the structure’s natural frequencies during the optimization process coupled with a design for an additive manufacturing approach, the operational range of the wind turbine was maximized, the overall costs were reduced, and production times were significantly diminished. Integrating the constraints associated with the additive manufacturing process into the design stage produced high-efficiency results with over 23% in weight reduction when compared with conventional structural optimization techniques.

Sound fields in ducts with ring-shaped cross-sections or in flat ducts with a circular bend of their axis can be represented as mode sums of modes in the cylindrical co-ordinate system in which the duct wall surfaces are co-ordinate surfcaces. Ring-shaped lined ducts are a common form of silencers; bent ducts with absorbing walls are favorite constructions as turning vanes for the flow in the corners of wind tunnels. The modal analysis of the sound fields in both types of ducts proceeds in parallel over wide parts. The most significant differences are found in the determination of the mode wave numbers. Whereas in the ring-shaped duct the arguments of the cylindrical functions are sought as radial wave numbers for given (mostly integer) orders of these functions, their (complex) orders are to be determined as azimuthal wave numbers in the curved duct, in which the arguments of the cylindrical functions can be supposed as known quantities, because their determination then is a rather simple standard task. If more than just the first-order approximation is required to the attenuation in a duct system containing a ring-shaped or a bent duct section (for that approximation the knowledge of the least attenuated mode would be sufficient) a set of mode wave numbers must be evaluated. This difficult sub-task of the modal analysis in both types of ducts is the principal topic of the present paper. The present part I of the paper is mainly concerned with curved ducts.

Numerous articles of individual high nitrogen stainless steel compositions or alloys with near identical alloy compositions have been published characterizing the properties the alloy or the improvement which an individual element contributes to the base alloy's properties. In this study a series of high nitrogen steels alloys were prepared with the intent of characterizing the advantages and limitations of different alloy chemistry on the base alloy's material properties such as: microstructure, mechanical properties, environmental interactions (corrosion and oxidation), and wear. A base composition of Fe-15Cr-15 Mn was chosen. Alloys of similar basic compositions are austenitic and often used as a starting composition as a substitute or replacements for Fe-Cr-Ni stainless steel alloys. Mn is less expensive than Ni, is a strong austenizer, enhances nitrogen solubility, and has no allergenic effects. To this base alloy composition additions of C, N, Si, Mo, and Nb was added. Nitrogen (and carbon) alloys as interstitials and have been shown to enhance strength and reduce corrosion. Niobium (or similar elements) is often added to produce intergranular carbide precipitates that further enhance strength. Molybdenum and silicon are added to improve corrosion-oxidation properties. This study was designed to evaluate the action and interaction of these different alloysmore » and suggest what alloys compositions are best used under different engineering requirements. The results of the experimental alloys are compared with that of two experimental higher-nitrogen commercial alloys steels with further alloy addition of Ni and Cu were also studied. Alloy evaluation included: (1) microstructure: optical, SEM, and X-ray diffraction, (2) mechanical properties: yield, tensile, elongation, hardness (room temperature and hot), and energy to failure, (3) oxidation and corrosion, and (4) abrasive wear: scratch, pin-on-drum, and pin-on-disk.« less

The solution of the problem of mathematical modeling of dynamic influences on building structures is considered in general and in connection with important scientific and practical tasks. In modern conditions, special attention should be paid to the problems of taking into account dynamic influences, parameters of load-bearing structures of buildings that affect their structural reliability and safety. For many years, information about catastrophic destruction of buildings and structures has been appearing more often, which are the result not only of errors that arose during the construction of facilities, but also due to dynamic influences that arose during their operation. A buildable technical system will be used in advance with the technical parameters set, which is responsible for the control of the process of the preparation of structures, the installation of the equipment, during the operation and operation. The development will be carried out and the sporud will be constantly used to promote the development of future technologies, the development and the establishment of the future, as well as the development of dynamic developments in the future. In particular, it is important to understand the development of the engineering and geological minds of the spores, as they have known the front deformation of the non-essential axis of the runt foundations. Various methods are used for structural dynamics, such as modal analysis, response spectrum analysis, time analysis, and finite element analysis. These methods include mathematical modeling, numerical simulation, and computational methods to predict the behavior and response of a structure under dynamic load conditions. Knowing the frequency and form of the structure, it is possible to estimate the dynamic reaction of the design to the application. For the purpose of including the transfer of the world, the destruction of internal forces in the real parts of the construction. Analyses of the response to the additional assessment of the characteristics of the construction, the identification of critical areas and the re-conversion, which the project is able to meet the criteria.

Ballistic impact-resistant materials are of interest for the past few decades. Ballistic impact is a high-velocity impact where the target material is perforated by the projectile, such as a bullet hitting on a surface. In this study, the effect of ballistic impact on thermoset composites, Kevlar–Epoxy, Carbon–Epoxy, Glass–Epoxy, and thermoplastic composite, Carbon–Polyetheretherketone, was done. Projectile residual velocity and projectile penetration depth were used to quantify the effectiveness of the composite material to resist perforation. The simulation study was done on ABAQUS-6.13. The study included preliminary fiber orientation studies and selection of the best performing composite with the most effective fiber orientation. Further, the selection of the best performing target material was done by varying target thickness and projectile velocity. In this study, high-performance Carbon–Polyetheretherketone composite showed the most impact resistance.

In this paper, modal analysis experiments on composite plates with and without delaminations are carried out. Specimens of the glass cloth and epoxy matrix composite plate, including plates without delamination and plates with through-width delaminations, are manufactured by the layup technique. A thin Teflon film is used to introduce the delamination during the manufacturing process. Delamination modes are found in delaminated plates by comparing the modal analysis results of the delaminated plates with the results of the nondelaminated plates. The sensitivity of the Teflon in the delamination area to the delamination modes is analyzed by the modal analysis experiments of the plates with Teflon in and out of the delamination area. Two delamination coefficients are defined to discern the delamination modes more quantitatively. According to the modal analysis results, the possibility of detecting the delamination size and location is discussed.