Search results

Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore aims to give the reader an encyclopaedic view on the subject. The bibliography at the end of the paper contains 2,025 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1992‐1995.

The catastrophic failures of these thick-wall cylinders are mainly due to the presence of inherent cracks in the material. The present study aims to deal with the analysis of stress for a given range of inside pressure. The paper deals with the calculation of radial and tangential stresses for various external pressure-to-internal pressure ratios and external radius to internal radius of the thick-walled cylinder.

The inlet line to the combustion chamber normally has an internal diameter of 150 mm and has a thickness of 25 mm. Normal temperature of the working fluid is about 80°C and the outside temperature is kept as room temperature. The present work deals with the stress analysis of the inlet line with and without internal crack. Also the stress intensity factors are calculated to check with the fracture toughness. Analysis is done both theoretically and by FEM by using the well-known software ANSYS.

Results show that the radial stress is independent of the external radius-to-internal radius ratio, while the tangential stress increases.

In process industries like nuclear or chemical, etc., structures in the form of thick-walled cylinders play a vital role, as its failure can affect humans and the environment. Because of this, the design and analysis of the above cylinders are of much significance.

Due to constant or cyclic operating pressure of pressure vessels and its corresponding pipelines usually in the form of thick-walled cylinders, reliability of the materials and structures used is of critical importance, as its failure can be deadly and possess lethal dangers when the cylinder contains flammable, toxic or reactive working fluid. The major ruling factors for the failure are none other than stress-related defects and presence of cracks.

A DSIR Sponsored Research Programme on the Development and Application of the Matrix Force Method and the Digital Computer. This work presents a rational method for the structural analysis of stressed skin fuselages for application in conjunction with the digital computer. The theory is a development of the matrix force method which permits a close integration of the analysis and the programming for a computer operating with a matrix interpretive scheme. The structural geometry covered by the analysis is sufficiently arbitrary to include most cases encountered in practice, and allows for non‐conical taper, double‐cell cross‐sections and doubly connected rings. An attempt has been made to produce a highly standardized procedure requiring as input information only the simplest geometrical and elastic data. An essential feature is the use of the elimination and modification technique subsequent to the main analysis of the regularized structure in which all cutouts have been filled in. Current Summary A critical historical appraisal of previous work in the Western World on fuselage analysis is given in the present issue together with an outline of the ideas underlying the new theory.

Field excited flux switching machines (FEFSM) are preferred over induction and synchronous machines due to the confinement of all excitation sources on the stator leaving a robust rotor. This paper aims to perform coupled electromagnetic thermal analysis and stress analysis for single phase FEFSM as, prolonged high-speed operational time with core and copper losses makes it prone to stress and thermal constraints as temperature rise in machine lead to degraded electromagnetic performance whereas the violation of the principle stress limit may result in mechanical deformation of the rotor.

This paper presents the implementation of coupled electromagnetic-thermal and rotor stress analysis on single-phase FEFSM with non-overlap winding configurations using finite element analysis (FEA) methodology in JMAG V. 18.1. three-dimensional (3D) magnetic loss analysis is performed and extended to 3D thermal analysis to predict temperature distribution on various parts of the machine whereas Stress analysis predicts mechanical stress acting upon edges and faces of the rotor.

Analysis reveals that temperature distribution and rotor stress on the machine is within acceptable limits. A maximum temperature rise of 37.7°C was noticed at armature and field windings, temperature distribution in stator near pole proximity was 35°C whereas no significant change in rotor temperature was noticed. Furthermore, principal stress at the speed of 3,000 rpm and 30,000 rpm was found out to be 0.0305 MPa 3.045 MPa, respectively.

The designed machine will be optimized for improvement of electromagnetic performance followed by hardware implementation and experimental testing in the future.

The model is developed for axial fan applications.

Thermal analysis is not being implemented on FEFSM for axial fan applications which is an important analysis to ensure the electromagnetic performance of the machine.

This paper gives a bibliographical review of the finite element methods (FEMs) applied to the analysis of ceramics and glass materials. The bibliography at the end of the paper contains references to papers, conference proceedings and theses/dissertations on the subject that were published between 1977‐1998. The following topics are included: ceramics – material and mechanical properties in general, ceramic coatings and joining problems, ceramic composites, ferrites, piezoceramics, ceramic tools and machining, material processing simulations, fracture mechanics and damage, applications of ceramic/composites in engineering; glass – material and mechanical properties in general, glass fiber composites, material processing simulations, fracture mechanics and damage, and applications of glasses in engineering.

This bibliography is offered as a practical guide to published papers, conference proceedings papers and theses/dissertations on the finite element (FE) and boundary element (BE) applications in different fields of biomechanics between 1976 and 1991. The aim of this paper is to help the users of FE and BE techniques to get better value from a large collection of papers on the subjects. Categories in biomechanics included in this survey are: orthopaedic mechanics, dental mechanics, cardiovascular mechanics, soft tissue mechanics, biological flow, impact injury, and other fields of applications. More than 900 references are listed.

Recent studies have proposed the application of local fatigue approaches based on fracture mechanics or on strain-life material relations for the fatigue analysis of metallic structures. However, only few studies in the literature apply local approaches in the riveted bridges analysis; although these approaches can be applied to any type of connections, requiring a detailed stress analysis of joints and, consequently, considerable computational resources costs. The approach based on S-N curves, formulated in nominal or net stresses, is more usual in the fatigue analysis of riveted bridges. Due to economic factors, riveted bridges have had their operating life extended, while changes in the transport system over the years have subjected such structures to overloads different from those originally planned. These bridges, most of them centenary, were not originally designed accounting for fatigue damage; they represent an important group of structures that are very likely subjected to significant fatigue damage indexes. These factors make necessary detailed residual fatigue life studies to substantiate the decisions of extend (or not) the operational period of these bridges. The paper aims to discuss these issues.

The present paper presents a methodology aiming at applying the local approaches in the fatigue analysis of riveted joints of metallic bridges, through the use of sub-modeling techniques and procedures automation. The use of such techniques made such an application viable by keeping the computational costs involved at a moderate level. The proposed procedures were demonstrated using the Trezói Railway Bridge, located on the Beira Alta line, Portugal, built shortly after the Second World War. The proposed set of procedures allowed, through finite elements analysis, to obtain the relevant stresses to perform local fatigue damage analysis. A global structural model was constructed, using beam elements, and local models of a critical node were built with solid finite elements. The structure is analyzed under the passage of regulatory trains. The details of the modeling performed and the computation of the principal stresses in the vicinity of a node and the tangential/circumferential stresses at the holes of two critical riveted connections of that node are analyzed and a fatigue damage analysis is carried out.

In the proposed submodelling approach, disassembling the complex riveted nodes into riveted subassemblies allowed the evaluation of the local stresses at riveted holes at an affordable computational cost.

A methodology is proposed to allow the application of local fatigue analysis in real complex riveted joints, mitigating the computational costs that would result from a full model of the node with all rivets.

Single‐pass girth butt welding of a carbon‐manganese pipe is studied numerically using the finite element codes ADINAT/ADINA. A rotationally symmetric finite element model is employed in both the thermal and mechanical analysis. This model is used to investigate the influence on the residual stress state of pipe geometry, mesh density and material modelling. The results from the present study are compared with previous results from two different FE analyses and an experimental investigation. One of the FE analyses was fully three dimensional and the other employed shell elements. The calculated residual stresses were found to differ significantly only when different material models were employed. The thermal strain seemed to be the material parameter with the largest influence on the residual stress state. Especially the changes in thermal strain during phase transformations seemed to have a great influence. This means that the temperature field should be determined accurately enough to predict when and where the different phase transformations occur. Almost the same residual stresses were obtained for two pipes with different pipe geometries and weld parameters.

Analysis of the thermal effects during the packaging process or in the actual operating environment is necessary to develop small monolithic integrated sensing chips with heterogeneous integration. The use of multiple layers and various materials in monolithic integrated sensing chips addresses the coefficient of thermal expansion (CTE) mismatch issue. The purpose of this study is to focus on the residual stress analysis of the shielding electrode, which is a metal film that prevents pull-in of proof-mass during anodic bonding in microelectromechanical system (MEMS) chips with pressure sensors embedded in an accelerometer.

The finite element model of the chip was built by the commercial software ANSYS, and the residual stress was evaluated during the die attachment process for the shielding electrode. Various shielding electrode materials and a proposed design with a keep-out zone to reduce the residual stress are discussed, with a focus on the relationship between the geometric parameters of the chip and the residual stress for copper shielding electrodes of different thicknesses.

The results of the finite element analysis showed that the use of polysilicon as a shielding electrode in the proposed design generated the lowest residual stress because of its low CTE. The maximum stresses in both of in-plane and out-of-plane directions in the finite element model were reduced by keep-out zone design for the proposed design of the copper shielding electrode, and had 11 times reduction in out-of-plane direction especially, according to the nonlinear analysis as the stress concentration point in the shielding electrode moved. Moreover, the design with a thinner shielding electrode, thinner glass substrate and higher CTE of the glass substrate also lowered the maximum von Mises stress. On the other hand, the stress level during the operating temperature, without considering residual stress, overestimated up to five times in the proposed design.

In this study, valuable suggestions are proposed for the design of chips with pressure sensors embedded in accelerometers.

The purpose of this paper is to present an analytical framework for predicting the residual stresses that result from the laser shock peening of a friction stir‐welded 2195 aluminum alloy sample, using the finite element software LS‐DYNA.

The pressures resulting from the laser peening are directly applied in an explicit transient analysis as forces. At the completion of the transient analysis, an implicit springback analysis is performed to determine the final residual stresses. This cycle is repeated for the appropriate number of peen applications, including the appropriate overlap of application areas. To validate the analytical framework, a comparison of residual stresses between analysis and a test specimen is made using laser‐peened base material which was not friction stir‐welded. Friction stir welding (FSW) causes residual stresses and material property variations. In this work, the varying material properties regions are simplified and defined as discrete, separate materials. The residual stresses resulting from the welding are introduced directly as initial conditions in the peening transient analysis and so are combined within the analysis with the residual stresses from the peening.

Comparisons made between the experimental and analytical residual stresses are generally favorable.

Analysis of the laser shock peening of FSW has not been accomplished previously.