Static and dynamic structural analyses for a 750 kN class liquid rocket engine with TVC actuation

Static and modal analyses of structures with different repeated patterns

Design, static structural analysis and topology optimization of a four wheeler connecting rod

A comprehensive finite element model incorporating the features of comprehensive wing model and finite element method is developed in this paper. This new model extends the applicability of comprehensive wing model from uniform composite wings to tapered composite wings. It preserves the simplicity of one-dimensional finite element but performs like three-dimensional finite element for wing structural analysis. To verify its accuracy and show its efficiency, this model which is applicable to the general dynamic analysis is reduced to two simple cases: static analysis and free vibration analysis. Based upon the reduction results for static and free vibration cases, several numerical examples of composite wing structures are presented such as tapered wings subjected to end load or uniform pressure, and free vibration of tapered wings. The numerical results show that the proposed model is much more efficient than the conventional finite element, and their differences are within 12% in all cases of composite wing structures.

This paper deals with; the problem occurred in six cylinders four stroke engine crankshaft. It consist of static structural analysis of six cylinder engine crank shaft. It identifies and solves the problem by using the modelling and simulation techniques. The main work was to model the crankshaft with dimensions and then simulate the crankshaft for static structural analysis. The topic was chosen because of increasing interest in higher payloads, lower weight, higher efficiency and shorter load cycles in crankshaft. The modelling software used is Unigraphics-NX7.5 for modelling the crankshaft. The analysis software ANSYS is used for structural analysis of crankshaft. The objective involves modelling and analysis of crankshaft, so as to identify the effect of stresses on crankshaft, to compare various materials and to provide possible solution. Results obtained from the aforementioned analysis were then used in optimization of the crankshaft. The first step in the optimization process was weight reduction of the component considering static loading. This required the stress range under static loading not to exceed the magnitude of the stress range in the original crankshaft. Possible weight reduction options and their combinations were considered. The optimization process resulted in a weight reduction, increased strength and a reduced cost of the crankshaft.

Elastic-plastic analysis of a nozzle corner crack by finite element method

While exact solutions for linear static analysis of most frame structures can be obtained by the finite element method, it is very difficult to obtain exact solutions for free vibration and harmonic analyses for non‐trivial cases. This paper presents a study on new finite element formulation and algorithms for exact solutions of undamped axial vibration problems of elastic bars. Appropriate shape functions are constructed by using the homogeneous governing equations, and based on the new shape functions, a novel element is formulated. An iterative procedure is proposed for determining both the exact natural frequency values and the corresponding vibration mode shapes. Exact solutions can also be obtained for undamped harmonic response analyses by using the new element, as its stiffness and mass matrices are exact for a specified frequency. Illustrative examples are presented to demonstrate the effectiveness of the proposed element and algorithm. Copyright © 2007 John Wiley & Sons, Ltd.

Dynamic characteristics and reliability of elastomeric pads are dominant components in the design methodology to satisfy the performance parameters under dynamic operations. The fatigue life of rubber pads fitted with elastomeric pads mainly depends upon elastomers; natural rubber, chloroprene, nitrile butadiene, silicon compounds, etc., additives, accelerators, activators, fillers, anti-degradants, and manufacturing processes. The performance of the elastomeric pad is evaluated based on service operation, simulation, and laboratory testing. New and failed elastomeric (EM) pads have been examined in the Indian Rubber Manufacturer’s Research Association IRMRA laboratory for detailed failure analysis of existing EM pads. Further, chemical and physical properties are also evaluated in M&C (Metallurgical and Chemical) and Testing Directorate of Research Designs and Standards Organization (RDSO), labs respectively. The fatigue life of the EM pad is estimated based on the results extracted from the Finite Element (FE) analysis of the EM pad. An attempt is made to modify the design of the EM pad by considering the results of detailed field trials, lab testing, and FE analysis. The modified design satisfies the dynamic characteristic during FE (Structural and Thermal) analysis and lab testing.

There exist different kinds of aircrafts, such as conventional airplane, rotorcraft, fighter, and unmanned aerial vehicle. Their shape and feature are dependent upon their own assigned mission. One of the fundamental analyses performed during the aircraft design is the structural analysis. It becomes more complicated and requires severe computations because of the recent complex trends in aircraft structure. In order for efficiency in the structural analysis, a simplified approach, such as equivalent beam or plate model, is preferred. However, it is not clear which analysis will be appropriate to analyze the realistic configuration, such as an aircraft wing, i.e., between an equivalent beam and plate analysis. It is necessary to assess the limitation for both the one-dimensional beam analysis and the two-dimensional plate theory. Thus, in this paper, the static structural analysis results obtained by EDISON solvers were compared with the three-dimensional results obtained from MSC NASTRAN. Before that, EDISON program was verified by comparing the results with those from MSC NASTRAN program and other analytic solutions.

Structural and thermal analysis on high-pressure steam turbine blade to determine the optimum material for its manufacturing

Elastic-plastic FEM-analysis of a nozzle corner crack and discussion of the results by some fracture mechanics concepts

Regression modeling and prediction of road sweeping brush load characteristics from finite element analysis and experimental results

A finite element model of an aircraft seat subjected to static certification loads (Certification Specifications CS25.561) involves material, geometric and contact non-linearities. Implicit algorithms can model the physics of such problems appropriately but suffer from shortcomings such as significant finite element modelling efforts, high disk space and memory requirements and unconverged solutions. Explicit finite element schemes offer a more robust alternative for convergence for quasi-static loadcases but may come at an even higher computational cost as smaller solution time steps are required, in addition to unwanted inertial effects. A methodology to apply an explicit formulation for simulating static certification loading for an aircraft seat-structure is presented and validated in this article. The first part reviews the design novelties of the triple seat-structure considered, the safety regulations used in aircraft seat certification. The key theoretical aspects of an explicit solver are presented, together with the numerical challenges faced when applied to solving quasi-static problems. Time scaling, mass scaling and damping are common approaches to assist in artificially reducing the computational time but previous articles provide little insight into how to apply these techniques correctly and the level of checking that is required to ensure the quality of the results are unaffected by these modifications. The main focus of this article is to clearly define the procedure to establish appropriate factors for mass scaling, time scaling and damping. Quality checks, such as ratio of kinetic energy to internal energy and their time-histories have been investigated to ensure a quasi-static solution. finite element analysis results are validated against experimental testing for the 8.6 g downward loadcase. Parameters such as kinematic behaviour and deflections at key locations been used for comparison. An acceptable level of correlation between finite element analysis results and physical tests validates the proposed methodology, which will be extended in a future article (Part II) to consider additional contact complexities with the inclusion of body blocks.

Rocket Motor Case (RMC) is a major component of Rockets and other Satellite launching vehicles. So, these structures should be of low weight, i.e. Low weight to high strength ratio materials, i.e., composite and alloys materials are used for main components. In the present analysis, 3-Dimensional finite element based static structural analysis and modal analysis are performed on the rocket motor case using aluminum alloy, titanium alloy, alloy steel, carbon epoxy and e glass epoxy. The problem is modeled in student version of ANSYS software. Stresses under radial, hoop, longitudinal directions are calculated with cylindrical co-ordinate system and list of natural frequencies and mode shapes are noted with respect to pre-stressed constrained and free- free boundary conditions. Later rectangular, semicircular, semi hexagonal and triangular types of stiffeners are introduced to the rocket motor case to perform static structural and modal analysis. The effect of stiffeners to the rocket motor case has studied for different materials under static and dynamic loading conditions. Best stiffener for rocket motor case is recommended based on the results, i.e., rectangular section having higher natural frequencies and semi hexagonal shape having less stresses in their respective directions.

With increases in ship size and speed, shipboard vibration becomes a significant concern in the design and construction of vessels. Excessive ship vibration is to be avoided for passenger comfort and crew habitability. In addition to the undesired effects on humans, excessive ship vibration may result in the fatigue failure of local structural members or malfunctioning of machinery and equipment. The propeller induces fluctuating pressure on the surface of the hull, which induces vibration in the hull structure. These pressure pulses acting on the ship hull surface above the propeller are the predominant factor for vibrations of ship structures are taken as excitation forces for forced vibration analysis. Ship structures are complex and may be analyzed after idealization of the structure. Several simplifying assumptions are made in the finite element idealization of the hull structure. In this study, a three-dimensional finite element model representing the entire ship hull, including the deckhouse and machinery propulsion system, has been developed using solid modeling software for local and global vibration analyses. Vibration analyses have been conducted under two conditions: free–free (dry) and in-water (wet). The wet analysis has been implemented using acoustic elements. The total damping associated with overall ship hull structure vibration has been considered as a combination of the several damping components. As a result of the global ship free vibration analysis, global natural frequencies and mode shapes have been determined. Moreover, the responses of local ship structures have been determined as a result of the propeller-induced forced vibration analysis.

FEPACS (Finite Element Package for linear static, dynamic and instability Analysis of Composite Structures under hygro-thermo-mechanical loads) incorporates a complete library of consistent and correct 1-, 2- and 3-dimensional linear and quadratic general purpose finite elements. In this paper, we shall discuss the finite element technology that has gone into the package as well as its present modelling and solution capabilities. We shall also discuss briefly recent developments toward enhancing the package: Robust composite elements based on aC 0-continuous higher order transverse deformation plate/beam theory, and nonlinear element technology and solution strategies. Finally, we shall also briefly touch upon several satellite application modules that are in different stages of planning/development to aid FEPACS: damage assessment/prediction,expert-like advisors for solid modelling and finite element modelling/analysis, pre-/post-processing for FEPACS applications, structural optimisation and related finite element algorithms, and finally, a frontal solution module for FEPACS to enhance its feasibility for vectorisation/parallelisation.