A Simple Numerical Method for Determining the Sensitivity of Bending Deflections of Stepped Shafts to Dimensional Changes

1985 ◽  
Vol 107 (1) ◽  
pp. 141-146
Author(s):  
G. Umasankar ◽  
C. R. Mischke
Keyword(s):  
Dimensional Change ◽  
Element Model ◽  
Neutral Axis ◽  
Computationally Efficient ◽  
Simple Method ◽  
Dimensional Changes ◽  
Stepped Shaft ◽  
Dimension Change ◽  
Deflection Analysis ◽  
Uniform Diameter

A simple method of computing the effect of a dimensional change at a particular element of a stepped shaft on two bearings, on bending deflections, and on slopes of the neutral axis at any of the nodes of interest is presented. The changes in deflection and slope of the neutral axis are derived as incremental quantities and as functions of the dimension change and the prior deflections and slopes of the neutral axis of the shaft. For shaft synthesis, the implications are that one can begin with a uniform diameter bar subjected to the loading and make a complete deflection analysis with superposed closed-form relations. Then the geometry can be modified element by element and the deflectional changes easily updated. This is computationally efficient. Further, deflections and deflection changes computed using the proposed method are identical to those obtained using a finite beam element model of the shaft.

scholarly journals A computationally efficient hybrid 2D–3D subwoofer model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmad H. Bokhari ◽  
Martin Berggren ◽  
Daniel Noreland ◽  
Eddie Wadbro
Keyword(s):  
Hybrid Model ◽  
3D Model ◽  
Element Model ◽  
Acoustic Properties ◽  
Computational Time ◽  
Average Response ◽  
Frequency Range ◽  
Computationally Efficient ◽  
Lumped Element ◽  
Lumped Element Model

AbstractA subwoofer generates the lowest frequency range in loudspeaker systems. Subwoofers are used in audio systems for live concerts, movie theatres, home theatres, gaming consoles, cars, etc. During the last decades, numerical simulations have emerged as a cost- and time-efficient complement to traditional experiments in the design process of different products. The aim of this study is to reduce the computational time of simulating the average response for a given subwoofer design. To this end, we propose a hybrid 2D–3D model that reduces the computational time significantly compared to a full 3D model. The hybrid model describes the interaction between different subwoofer components as interacting modules whose acoustic properties can partly be pre-computed. This allows us to efficiently compute the performance of different subwoofer design layouts. The results of the hybrid model are validated against both a lumped element model and a full 3D model over a frequency band of interest. The hybrid model is found to be both accurate and computationally efficient.

Comparison of Different Methods for Stress and Deflection Analysis in Embedded Die Packages during the Assembly Process

2014 ◽  
Vol 2014 (1) ◽  
pp. 000355-000360
Author(s):  
K. Macurova ◽  
R. Bermejo ◽  
M. Pletz ◽  
R. Schöngrundner ◽  
T. Antretter ◽  
...  
Keyword(s):  
Printed Circuit Board ◽  
Plastic Material ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Element Model ◽  
Analytical Investigation ◽  
Circuit Board ◽  
Curvature Radius ◽  
Assembly Process ◽  
Deflection Analysis

Important topics for electronic packages are thermally induced stresses created during package manufacturing and their role in mechanical failure. In the present paper, an analytical and a numerical analysis of the assembly process (component attached with an adhesive to a copper foil) is investigated. This process is prior to the lamination of the printed circuit board. Stresses develop due to a mismatch of coefficients of thermal expansion and particularly to shrinkage associated with adhesive polymerization. The analytical investigation is based on the classical laminate theory and an interfacial model. The three-dimensional numerical finite element model is capable to use geometric and material properties which are not possible to investigate analytically. In particular, the influence of the adhesive meniscus and plastic material models for copper and adhesive are investigated. The models are validated experimentally by an X-ray diffraction method (Rocking-Curve-Technique) showing a good agreement of the calculated and measured curvature radius values.

Comparison of Different Methods for Stress and Deflection Analysis in Embedded Die Packages During the Assembly Process

2015 ◽  
Vol 12 (2) ◽  
pp. 80-85 ◽  
Author(s):  
K. Macurova ◽  
R. Bermejo ◽  
M. Pletz ◽  
R. Schöngrundner ◽  
T. Antretter ◽  
...  
Keyword(s):  
Printed Circuit Board ◽  
Plastic Material ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Element Model ◽  
Analytical Investigation ◽  
Circuit Board ◽  
Curvature Radius ◽  
Assembly Process ◽  
Deflection Analysis

Important topics for electronic packages are thermally induced stresses created during package manufacturing and their role in mechanical failure. In the present paper, an analytical and a numerical analysis of the assembly process (component attached with an adhesive to a copper foil) is investigated. This process is prior to the lamination of the printed circuit board. Stresses develop due to a mismatch of coefficients of thermal expansion and particularly to shrinkage associated with adhesive polymerization. The analytical investigation is based on the classical laminate theory and an interfacial model. The three-dimensional, numerical, finite element model is capable of using geometric and material properties not possible to investigate analytically. In particular, the influence of the adhesive meniscus and plastic material models for copper and adhesive are investigated. The models are validated experimentally by an x-ray diffraction method (rocking-curve technique) showing a good agreement of the calculated and measured curvature radius values.

Dynamic moisture sorption and dimensional stability of furfurylated wood with low lignin content

Holzforschung ◽  
2019 ◽  
Vol 74 (1) ◽  
pp. 68-76
Author(s):  
Tiantian Yang ◽  
Erni Ma ◽  
Jinzhen Cao
Keyword(s):  
Relative Humidity ◽  
Dimensional Stability ◽  
Furfuryl Alcohol ◽  
Lignin Content ◽  
Moisture Sorption ◽  
Dimensional Change ◽  
Poplar Wood ◽  
Sorption Coefficient ◽  
Dimensional Changes ◽  
Sinusoidal Shape

AbstractDegradation of lignin occurs naturally in wood due to the influence of microorganisms or photic radiation. To improve the properties of wood with low lignin content, furfuryl alcohol (FA) at the concentration of 25% was used to modify poplar wood (Populus euramericana Cv.) after partial delignification. Moisture sorption and dimensional stability of the samples were investigated under dynamic conditions where the relative humidity (RH) was changed sinusoidally between 45% and 75% at 25°C. Both the moisture content (MC) and the tangential dimensional change varied with a sinusoidal shape similar to the RH. Hygroscopicity and hygroexpansion increased after delignification, while furfurylation led to an inverse impact by reducing MC, dimensional changes, amplitudes of MC and dimensional changes, moisture sorption coefficient (MSC), and humidity expansion coefficient (HEC). After delignification and further furfurylation, the MC and the dimensional changes were reduced by about 20%, and the maximum drop in amplitudes of MC and dimensional changes was about 30%, while the MSC and the HEC decreased by over 15%. In addition, the furfurylated wood with low lignin content exhibited lower sorption hysteresis and swelling hysteresis.

Changes in the dimensions of the venae cavae

1959 ◽  
Vol 196 (4) ◽  
pp. 741-744 ◽  
Author(s):  
Hiroshi Irisawa ◽  
Alexander P. Greer ◽  
Robert F. Rushmer
Keyword(s):  
Venous Pressure ◽  
Dimensional Change ◽  
Venous Flow ◽  
Dimensional Changes ◽  
Cyclic Patterns ◽  
Venae Cavae ◽  
Surgical Conditions ◽  
Two Phases ◽  
Pressure Changes ◽  
Clockwise Hysteresis

In 11 dogs a variable resistance gauge, a bonded strain gauge, or mutual inductance coils were installed on the venae cavae under aseptic surgical conditions so that dimensional changes in unexposed veins could be measured directly. The cyclic patterns of dimensional change resembled inverted images of venous flow records obtained by others. Since some changes in the venous dimensions apparently were not related to pressure, active contraction of the walls may have been responsible. Studies involving infusion and hemorrhage confirmed the existence of two phases in the pressure-diameter relationship correlated with the level of venous pressure. The pattern of diameter and venous pressure changes during transfusion and withdrawal of blood tended to be a clockwise hysteresis loop.

Dimensional Changes of Graphite Flakes and Fracture in Tensile Tests of Gray Cast Iron

2018 ◽  
Author(s):  
Naoya Tada ◽  
Takeshi Uemori
Keyword(s):  
Cast Iron ◽  
Tensile Test ◽  
Internal Combustion Engines ◽  
Gray Cast Iron ◽  
Early Stage ◽  
Dimensional Change ◽  
Tensile Tests ◽  
High Ratio ◽  
Gray Cast ◽  
Dimensional Changes

Gray cast iron has been used as a component in various mechanical parts, such as the blocks and heads of automobile and marine engines, cylinder liners for internal combustion engines, and machine tool bases. It is desirable because of its good castability and machinability, damping characteristics, and high ratio of performance to cost. On the other hand, the weak graphite flakes present in gray cast iron act as stress concentrators and negatively affect the strength of this material. It is therefore important to know the relationship between the distribution of graphite flakes and the strength or fracture of gray cast iron. In this study, a tensile test of gray cast iron was carried out using a plate specimen in a scanning electron microscope, and the microscopic deformation was observed on the surface of specimen. Particularly, the change in the size of graphite flakes during the tensile test was examined, and the observed trend was discussed. We found from the experimental results that the dimensional changes in the graphite flakes varied in the observed area, and that the final fracture occurred in an area where a relatively large dimensional change was observed. This suggests that the fracture location or the critical parts of gray cast iron, can be predictable from the dimensional changes of the graphite flakes at an early stage of deformation.

An inverse position analysis of five-bar planar parallel manipulators

Robotica ◽  
2002 ◽  
Vol 20 (2) ◽  
pp. 195-201 ◽  
Author(s):  
Gürsel Alici
Keyword(s):  
Parallel Manipulators ◽  
Joint Space ◽  
Computationally Efficient ◽  
Simple Method ◽  
Cartesian Coordinates ◽  
Reachable Workspace ◽  
Prismatic Joints ◽  
Inverse Position Analysis ◽  
Translational Joint ◽  
Planar Parallel Manipulators

In this paper, we present a simple method to obtain joint inputs needed to attain any point in the reachable workspace of a class of five-bar planar parallel manipulators which are based on five rigid links and five single degree of freedom joints – revolute and prismatic joints. Depending on the topology of the manipulators, two mathematical expressions describing the path traced by the tip of two links connected to each other are obtained and solved simultaneously in order to determine the intersection points of the two paths which are the Cartesian coordinates of the connection points for the links. For the class of manipulators considered in this study, one of the links is the link activated by an actuator fixed to the ground. So, rotational and/or translational joint inputs can be determined from the Cartesian coordinates of the tip of the activated links. Sylvester's dialytic elimination method is employed to solve the equations. Such a methodology is easy to implement, computationally efficient and sound to compute all possible solutions. A numerical example is provided for each manipulator and the inverse position solutions are verified by substituting them into forward position equations. It is concluded that the proposed method is useful in trajectory planning and control of five-bar planar parallel manipulators in joint space.

Dimensional Changes by Heat Treatment of Helical Gear

2013 ◽  
Vol 535-536 ◽  
pp. 271-274
Author(s):  
Jeongsuk Lim ◽  
Sunghoon Kang ◽  
Young Seon Lee
Keyword(s):  
Heat Treatment ◽  
Elastic Deformation ◽  
Gear Tooth ◽  
Three Dimensional ◽  
Dimensional Change ◽  
Helical Gear ◽  
Tooth Profile ◽  
Dimensional Changes ◽  
Gear Teeth ◽  
Experimental Works

The dimensional change of tooth profile by heat treatment of helical gear was investigated by experimental and numerical approaches. Especially, the three-dimensional elasto-plastic finite element (FE) simulation was adopted to analyze the elastic deformation during load, unloading, ejecting of workpiece. Quenching simulation was also carried out to investigate the change of tooth profile on the forged gear. In experiments, the amount of elastic deformation of the forged gear was quantitatively determined by comparing the tooth profiles on the forged gear and die. The dimensional change of the forged gear tooth after quenching was also evaluated from the comparision of the cold forged and quenched gear teeth. From experimental works, it was found that the amounts of dimensional changes after forging and quenching of helical gear are 10 and 10 μm, respectively.

scholarly journals Anodization Parameters Influencing the Growth of Titania Nanotubes and Their Photoelectrochemical Response

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Ying-Chin Lim ◽  
Zulkarnain Zainal ◽  
Wee-Tee Tan ◽  
Mohd Zobir Hussein
Keyword(s):  
Dimensional Change ◽  
Bath Temperature ◽  
Tube Length ◽  
Complexing Agent ◽  
Dimensional Changes ◽  
Photoelectrochemical Response ◽  
Voltage Ramp ◽  
Wide Range ◽  
Electrode Cell ◽  
Nanotube Growth

TiO2nanotubes (TNTs) were fabricated by electrochemical oxidation of Ti foil in a standard two-electrode cell-containing NH4F. The effects of bath temperature, voltage ramp prior to constant voltage held during anodization and present of complexing agent on the crystalline phase, nanotube growth, and dimensional change of TNT were investigated using XRD and FESEM. The results show that tube length decreases with bath temperature attributed to faster chemical dissolution rate at high temperature. However, nanotubes growth rate was enhanced by ~260% with the addition of EDTA as the complexing agent. Meanwhile, the nanotubes diameter was found to be proportionally dependent on bath temperature but independent of the voltage ramp and addition of EDTA. Photoelectrochemical response under illumination was enhanced by using the calcined TNT and is strongly affected by its dimensional changes. Thus, desired properties of TNT can be obtained by tuning the electrochemical condition for a wide-range application.

Recent Developments of Magnetic SMA

2008 ◽  
Vol 59 ◽  
pp. 1-10 ◽  
Author(s):  
Outi Söderberg ◽  
Ilkka Aaltio ◽  
Yan Ling Ge ◽  
Xu Wen Liu ◽  
Simo Pekka Hannula
Keyword(s):  
Magnetic Field ◽  
Phase Transformation ◽  
Shape Memory ◽  
Dimensional Change ◽  
Magnetic Shape Memory ◽  
Dimensional Changes ◽  
Different Types ◽  
Recent Developments ◽  
Giant Magnetocaloric Effect ◽  
The Magnetic Field

In the shape memory alloys (SMAs) the thermal triggering induces reversible dimensional change by the phase transformation – these materials may also be ferrior ferromagnetic, however, here only the ferromagnetic SMAs are discussed. In certain SMAs the austenitemartensite phase transformation is influenced by the magnetic field as either austenite or martensite is promoted by the field and this is exploited for the dimensional changes. However, in the magnetic shape memory (MSM) alloys no phase transformation occurs as the remarkable dimensional changes take place by the twin variant changes in the martensitic phase activated by the external magnetic field at constant temperature. In addition to the phase transformation or magnetic shape memory effect, the applied magnetic field may also result in the conventional magnetostriction (MS), enhance the superelasticity (magneticfieldassisted superelasticity MFAS) or induce the giant magnetocaloric effect (GMCE). Certain alloys such as NiMnGa may even be multifunctional showing more than one of these effects. The present paper gives an overview of the different types of the magnetically activated SMA alloys, their properties as well as their potentials for applications in the frameworks of the recent studies.

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