Influence of External Loads on Thin Film Cracking

2004 ◽  
Author(s):  
Srinath S. Chakravarthy ◽  
Eric H. Jordan ◽  
Wilson K. S. Chiu
Keyword(s):  
Thin Film ◽  
External Load ◽  
Crack Arrest ◽  
External Loading ◽  
Element Analysis ◽  
Film Cracking ◽  
Two Parameters ◽  
Improved Accuracy ◽  
External Loads

Cracking in thin films under the combined influence of residual stress and an external load is examined. An improved accuracy version of the existing solution for substrate cracking absent the external load is provided. A superposition scheme that uses the solution for substrate cracking and other existing published solutions is presented for the determination of the energy release rate. The superposition scheme is validated using finite element analysis, and conditions under which the superposition scheme is valid are discussed. Crack arrest is examined and two parameters that determine the possibility of crack arrest are identified. The influence of external loading on channelling behavior in the substrate is discussed.

Determination of critical angle of circumferential throughwall crack for structurally distorted 90° pipe bends under bending moment with and without internal pressure

2017 ◽  
Vol 233 (5) ◽  
pp. 817-830 ◽  
Author(s):  
S Sumesh ◽  
AR Veerappan ◽  
S Shanmugam
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Closed Form ◽  
Bending Moment ◽  
External Loading ◽  
Element Analysis ◽  
Critical Crack ◽  
Structural Distortions ◽  
Internal Pressures

Throughwall circumferential cracks (TWC) in elbows can considerably minimize its collapse load when subjected to in-plane bending moment. The existing closed-form collapse moment equations do not adequately quantify critical crack angles for structurally distorted cracked pipe bends subjected to external loading. Therefore, the present study has been conducted to examine utilizing elastic-plastic finite element analysis, the influence of structural distortions on the variation of critical TWC of 90° pipe bends under in-plane closing bending moment without and with internal pressure. With a mean radius ( r) of 50 mm, cracked pipe bends were modeled for three different wall thickness, t (for pipe ratios of r/ t = 5,10,20), each with two different bend radius, R (for bend ratios of R/r = 2,3) and with varying degrees of ovality and thinning (0 to 20% with increments of 5%). Finite element analyses were performed for two loading cases namely pure in-plane closing moment and in-plane closing bending with internal pressure. Normalized internal pressures of 0.2, 0.4, and 0.6 were applied. Results indicate the modification in the critical crack angle due to the pronounced effect of ovality compared to thinning on the plastic loads of pipe bends. From the finite element results, improved closed-form equations are proposed to evaluate plastic collapse moment of throughwall circumferential cracked pipe bends under the two loading conditions.

A frequency response function-based updating technique for the finite element model of automotive structures

2008 ◽  
Vol 222 (10) ◽  
pp. 1781-1791 ◽  
Author(s):  
D-C Lee ◽  
C-S Han
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Design Parameters ◽  
External Loading ◽  
Element Analysis ◽  
Automotive Structures ◽  
Different Types ◽  
External Loads ◽  
The Finite Element Model ◽  
Huge Variety

Today's automotive industry uses finite element analysis (FEA) in a huge variety of applications in order to optimize structures and processes before hardware is produced. Efficiencies can be enhanced and margins are reduced because the external loads and structural properties are identified with higher confidence. The accuracy of FEA predictions has become increasingly important and directly influences the competitiveness of a product on the market. Because automotive structures are under dynamic environments, the correlation on the basis of static deformations independent of the mass and damping parameters do not provide a valuable reference from the view of the dynamic characteristics. In this paper, by systematically comparing the results from analytical and experimental analysis techniques, finite element (FE) models can be validated by the deterministic and robust design on the basis of each tolerance of design parameters, and improved so that they can be used with more confidence in further analysis. Making use of different types of test datum, a recommended procedure is to use a sequence of analysis in which mass, stiffness, damping, and external loading are validated and, if necessary, updated.

Substrate Effect on Modulus of Elasticity and Hardness of Thin Film Under Nanoindentation Test

2012 ◽  
Author(s):  
Mesbah U. Ahmed ◽  
Rafiqul A. Tarefder
Keyword(s):  
Thin Film ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Modulus Of Elasticity ◽  
Empirical Relationship ◽  
Nanoindentation Test ◽  
Substrate Effect ◽  
Element Analysis ◽  
Al Thin Film

Mechanical properties of thin film under nanoindentation test by Finite Element Analysis (FEA) have been studied in this literature. An axi-symmetric bi-layer model has been developed in commercial finite element analysis software, ABAQUS. Aluminum (Al) comprises the thin film whereas Silicon (Si) comprises the substrate. This model has been simulated using the loading condition that mimics real nanoindentation test, i.e. an indenter has been probed to a predefined depth onto Al-thin film. Modulus of elasticity and hardness of thin film have been calculated by existing empirical relationship. Substrate effect on determination of film modulus and hardness has been investigated by varying the substrate modulus. It has been observed that substrate effect is pronounced on film modulus determination whereas hardness is not significantly sensitive to this effect. Depth of indentation has also been varied over a long range to observe the indentation effect on these parameters. It is obvious that film modulus is increased with depth increment. However, hardness variation is not regular. Different friction condition is also in the scope of this study. It has been observed that friction does not affect modulus of elasticity. It, however, affects hardness of thin film. This is attributed to the dissipation of the energy needed to overcome friction at film-indenter interface.

scholarly journals Design and Analysis of a Drilling Fixture

2020 ◽  
pp. 56-60
Keyword(s):  
Element Analysis ◽  
Accuracy And Precision ◽  
Manufacturing Sectors ◽  
Manual Handling ◽  
Displacement Theory ◽  
Solid Works ◽  
Critical Components ◽  
Improved Accuracy ◽  
External Loads ◽  
Conventional Drilling

The Automation field is rapidly taking over the production and manufacturing sectors because of its heightened performance with improved accuracy and precision. Therefore, it is essential to understand the application and the significance of the involvement of automation in conventional drilling machines. The CAD geometry of the project is prepared in Solid Works, and finite element analysis considering the von misses stress, and displacement theory is carried out to find the effects of external loads on the motors and critical components of the fixture. The analysis where performed based on load calculated to be of 580.75 N, which gives stresses ranging of 1.466 to 117.7 MPa in the components. The project goal underscores the advantages of automation in drilling, including identifying and correcting errors occurring due to manual handling of systems. This project raises procedures for maintaining, setting up the work and work holding devices to get the job done accurately

The Determination of Equilibrium Configurations of Spring-Restrained Mechanisms Using (4 × 4) Matrix Methods

1967 ◽  
Vol 89 (1) ◽  
pp. 87-93 ◽  
Author(s):  
D. F. Livermore
Keyword(s):  
Kinematic Chain ◽  
External Loading ◽  
Matrix Methods ◽  
Kinematic Chains ◽  
Equilibrium Configurations ◽  
Force Systems ◽  
Velocity Information ◽  
Equilibrium Analyses ◽  
External Loads

A spring-restrained, multiple-loop, multiple-degree-of-freedom kinematic chain will normally have one or more stable equilibrium configurations when steady external loads are applied to it. The “kinematic equivalent” of a vehicle and its suspension linkages is a common example of such a system. Changes in external loading due to cornering, braking, and so on, can produce important changes in the equilibrium configuration of the suspension. This paper presents a general method for determining the equilibrium configurations of spring-restrained, kinematic chains under the action of steady external loading. The iterative (4 × 4) matrix method of displacement analysis, previously developed for single-loop chains, is extended to complex chains and is used to determine the displacement and velocity information required for equilibrium analyses. The final results are general computer programs which will determine displacement and/or equilibrium configurations for simple or complex mechanism systems wherein the applied force systems may be considered conservative.

Stresses in Nozzle Shell Junctions due to External Loads: A Comparative Study

2013 ◽  
Author(s):  
Dipak K. Chandiramani ◽  
Suresh K. Nawandar ◽  
Shyam Gopalakrishnan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Theoretical Background ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Section Viii ◽  
Division 2 ◽  
External Loads ◽  
Element Method

Various methods have been in use for the determination of stresses at the nozzle-shell junction due to external loads and moments. Some methods evaluate stress in the cylindrical or spherical shell (e.g. WRC 107 now WRC 537) while others evaluate stresses in cylindrical shells and nozzles (e.g. WRC 297). ASME Section VIII Division. 2 specifies use of WRC 107/WRC 297 or Finite Element Analysis (FEA) for determination of stresses at shell-nozzle junctions with external loads and moments on the nozzle. Each method could yield a different result for the same loading condition and geometry and this has been recognized in comparisons made in WRC 297 with WRC 107 and FEA. Further, customized FEA software are also available for this analysis. There still seems to be some confusion in users of these methods regarding selection of method for optimization of design. Users not familiar with Finite Element Method prefer to use calculations based on WRC 107/297. Hang-Sung Lee, et.al. have recently (PVP 2011 – 57407) analyzed nozzle shell junctions using the Finite Element Method, compared their results with calculations to WRC 297 and made recommendations. The work presented in this paper is not an attempt to compare individual stresses obtained by classical versus analytical methods. Instead, an attempt has been made to consolidate the results obtained by the various methods into charts to enable a user to make a preliminary assessment to ascertain under what geometrical conditions the calculations made by each of the above methods would result in overall Code acceptable stresses without the results being either overly conservative or un-conservative. This is particularly relevant to the geometries which use the graphs and charts which have been extrapolated without rigorous theoretical background in the WRC Bulletin 537. The Finite Element Method has been used as the referee method.

The Dynamic Balancing Performance of the Machinery Based on Virtual Prototyping Technology

2010 ◽  
Vol 34-35 ◽  
pp. 1200-1204
Author(s):  
Hui Wang ◽  
Ying Jian Pan
Keyword(s):  
External Load ◽  
Dynamic Balance ◽  
Virtual Prototyping ◽  
Moment Of Inertia ◽  
External Loading ◽  
Practical Application ◽  
Dynamic Balancing ◽  
Traditional Methods ◽  
Virtual Prototyping Technology ◽  
External Loads

The machine is subjected to the inertial effect produced by its inherent mass and moment of inertia from working parts besides external load during operation processes. In the traditional methods of machinery dynamical balancing, the influences of the friction, gravity and the external loads (working load) haven’t been considered. In this paper, the external loading has become an important factor in dynamical balancing problems. Based on Virtual Prototyping (VP) technology, we studied the effect of loading to dynamical balancing when taking several kinds of targets as the optimized goal. The conclusion has significance value for practical application and offers some references to dynamic balance of other mechanisms.

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

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