Deflection Properties Research Articles

Evaluation of Force Deflection Properties of Various Types of Initial Orthodontic Archwires

Evaluation of Force Deflection Properties of Various Types of Initial Orthodontic Archwires

Damping of unwanted turbulence in wave–current experiments

Laboratory testing of structures placed in combined wave–current flows is a valuable source of information for the fulfillment of offshore engineering related tasks and the development of ocean energy devices. In recirculating wave–current flumes, one of the problems encountered during such experimental studies is the occurrence of undesirable current induced velocity fluctuations. These fluctuations often result in significant disturbances of the generated wave profiles. In this paper, a physical flow filter is introduced that significantly reduces fluctuations in the current profile while permitting wave passage. This is achieved by passing the wave–current flow through a setup of perforated net tubes that allows for both horizontal and vertical flow motions. An in depth investigation of the properties of different filter configurations is presented, focusing on the reduction of turbulence intensities in the flow field as well as the influence of the setup on waves. The filter characteristics are quantified in terms of its deflection, absorption, and transmission properties. It is shown that the overall setup effectively reduces velocity fluctuations, resulting in stable wave–current conditions and allowing for high quality laboratory testing.

Numerical analysis and optimal design for new automotive door sealing with variable cross-section

Automotive door sealing system isolates passenger compartment from water, dust and wind noise. It has the most direct influences on door-closing performance, which is determined by cross-section design in terms of its appropriate Compression Load Deflection (CLD) property. Traditional sealing structure has uniform geometrical cross-section. It has the shortcomings of bad fitting in corner parts with large curvatures, causing inaccurate door-closing effort design. Regarding the door panel׳s complex 3D profile, numerical analysis and optimal design for new sealing with variable cross-section are developed in this paper. Firstly, the whole sealing is partitioned into several parts. For four nearly straight segments, conventional 2D numerical analysis can still be used to obtain desired geometrical configuration. For other four curved corner parts with large curvatures, 3D numerical analysis of door closing is applied. Secondly, 2D geometrical cross-section optimization is proposed. Instead of three variables in previous research, five variables are selected for featuring cross-section geometry and used for next CAD reconstruction with more precision. After comparison between Back Propagation (BP) neural network and the Kriging surrogate model, BP neural network which performs better and efficient in this automotive design optimization field is applied for extracting nonlinear mapping between five cross-section parameters and compression load, which were parallely optimized by Genetic Algorithm (GA) and its efficiency and accuracy are compared with another evolutionary algorithm of Particle Swarm Optimization (PSO). Thirdly, 3D numerical modeling of four curved corner parts׳ closing process is realized, of which twisting and bending effects during seal assembly are taken into account, thus minimizing theoretical error and producing more realistic solution. Consequently, the desired geometrical configurations for both straight parts and corner parts satisfying designated CLD property can be obtained and the whole sealing can be achieved with variable cross-section, resulting in an ideal door closing effort. Finally, a Matlab-based platform has been developed to assist the design and optimization process. Experiment and case study indicates that it provides an effective method for new door sealing design with variable cross-section.

A concept study of a carbon spar cap design for a 80m wind turbine blade

The buckling resistance is a key design driver for large wind turbine blades with a significant influence on the material costs. During the structural design process the choice was made for carbon spar caps and two shear webs, which were set relatively far apart in order to stabilize the panels. This design presented a major challenge for the stability of the spar caps. The topology of these spar caps has been modified with regard to stability, comparing a continuous spar cap with split spar cap concepts and considering both lay-ups with hybrid carbon glass spar caps or sandwich concepts. Within those concepts, parametric studies were conducted varying different geometrical parameters of the spar caps and its layups. In order to determine the buckling resistance of the spar cap, an analytical model considering a 2D cross section discretized blade model was utilized to select the basic concept, after which a 3D numerical finite element model taking the whole blade into account was used to evaluate the chosen design concepts. The stability limit state analysis was conducted according to the certification scheme of GL guideline 2012. The various concepts were evaluated based on the blade's mass, tip deflection and modal properties. The results of this design process of the spar caps and the evaluation of the used analysis tools are presented within the paper.

Multi-scale analysis of optic chiasmal compression by finite element modelling

The precise mechanism of bitemporal hemianopia (a type of partial visual field defect) is still not clear. Previous work has investigated this problem by studying the biomechanics of chiasmal compression caused by a pituitary tumour growing up from below the optic chiasm. A multi-scale analysis was performed using finite element models to examine both the macro-scale behaviour of the chiasm and the micro-scale interactions of the nerve fibres within it using representative volume elements. Possible effects of large deflection and non-linear material properties were incorporated. Strain distributions in the optic chiasm and optic nerve fibres were obtained from these models. The results of the chiasmal model agreed well with the limited experimental results available, indicating that the finite element modelling can be a useful tool for analysing chiasmal compression. Simulation results showed that the strain distribution in nasal (crossed) nerve fibres was much more nonuniform and locally higher than in temporal (uncrossed) nerve fibres. This strain difference between nasal and temporal nerve fibres may account for the phenomenon of bitemporal hemianopia.

1029 Deflection and flow properties of four 200µm laser fibres during flexible ureterorenoscopy

1029 Deflection and flow properties of four 200µm laser fibres during flexible ureterorenoscopy

RETRACTED: Characterization of Force Deflection Properties for Vehicular Bumper-to-Bumper Interactions

This article has been retracted due to incomplete content. The complete article (doi:10.4271/2014-01-1991) is published in the July issue of the SAE International Journal of Transportation Safety. Language: en

Characterization of Force Deflection Properties for Vehicular Bumper-to-Bumper Interactions

This is the complete manuscript and replacement for SAE paper 2014-01-0482, which was retracted due to incomplete content. This paper reports on 76 quasi-static tests conducted to investigate the behavior of road vehicle bumper systems. The tests are a quasi-static replication of real world low speed collisions. The tests represented front to rear impacts between various vehicles. Force and deflection were captured in order to quantify the stiffness characteristics of the bumper-tobumper system. A specialized test apparatus was constructed to position and load bumper systems into each other. The purpose was to replicate or exceed damage that occurred in actual collisions. The fixture is capable of positioning the bumpers in various orientations and generates forces up to 50 kips. Various bumper-to-bumper alignments were tested including full overlap, lateral offset, and override/underride configurations. Force and displacement were recorded and the data was analyzed to develop system stiffness and crush parameters. These parameters can be used in a collision-based model to calculate vehicle delta-v (ΔV) and acceleration. The simulation uses an impact mechanics-based numerical algorithm published by Scott [6]. The paper reports on the test results of various combinations of vehicle categories. Vehicle type includes passenger, light transport and heavy vehicle bumper systems. Language: en

Nonlinear analysis of carbon nanotube-based nanoelectronics devices

The paper deals with the investigation of nonlinear static and dynamic behaviors of electrostatically actuated carbon nanotubes with different geometries and boundary conditions. The deflection and pull-in properties are studied in detail in the presence of DC and combined DC + AC electrostatic voltages accompanying the interatomic interactions. The considered nano system can be applied in a wide range of nanoelectronics devices such as nano switches, nano resonators, nano transistors, nano capacitors and random access memories. Moreover, a useful mathematical model of the nano sensor application of the studied nano system to sense the stiffness of the nano particles is presented.

Deflection properties of an electrostatic electron lens with a shifted electrode

In this paper, the authors discuss a new electron optical component: an electrostatic lens in which one electrode is intentionally shifted laterally, breaking the rotational symmetry. This lens is called a “shift lens.” Usually, a shifted electrode is undesired, and the resulting aberrations are calculated only for the purpose of setting manufacturing requirements. However, the shift lens can be applied as a deflector. Thus, in multibeam systems with an individual microlens for each beam, all beams can be deflected with a single voltage. By giving a different shift to each lens, the deflection can be different for each beam. This allows the creation of a multibeam rotation error corrector. The optical properties of an electrostatic five-electrode lens with a shifted middle electrode are analyzed in this paper. For describing the optical properties of the shift lens, a simple mirror symmetric model in combination with Taylor polynomials is used. This model is then verified with a newly developed ray-tracing program, and the obtained aberrations are discussed. The middle electrode is shifted over a range of 1%–20% of the diameter of the lens. The authors have found dependences of deflection, defocus, astigmatism, and second order on shift distance and excitation. The authors expect the shift lens to be a useful new optical component, especially in multibeam systems.

Homotopy Perturbation Method for Nonlinear Vibration Analysis of Functionally Graded Plate

In this paper, the Homotopy perturbation method (HPM) is used to analysis the geometrically nonlinear vibrations of thin rectangular laminated functionally graded material (FGM) plates. The Von Karman's strain-displacement relations have been employed to model structural nonlinearity of the system. The material properties of the plate are assumed to be graded continuously in direction of thickness. The effects of initial deflection, aspect ratio and material properties are investigated. Based on the results of this study, the first order approximation of the HPM leads to highly accurate solutions for geometrically nonlinearity vibration of FGM plates. Moreover, HPM in comparison with other traditional analytical methods (e.g., perturbation methods) has excellent accuracy for the whole range of oscillation amplitude and initial conditions.

Finite Element Analysis of a Natural Fiber (Maize) Composite Beam

Natural fiber composites are termed as biocomposites or green composites. These fibers are green, biodegradable, and recyclable and have good properties such as low density and low cost when compared to synthetic fibers. The present work is investigated on the finite element analysis of the natural fiber (maize) composite beam, processed by means of hand lay-up method. Composite beam material is composed of stalk-based fiber of maize and unsaturated polyester resin polymer as matrix with methyl ethyl ketone peroxide (MEKP) as a catalyst and Cobalt Octoate as a promoter. The material was modeled and resembled as a structural beam using suitable assumption and analyzed by means of finite element method using ANSYS software for determining the deflection and stress properties. Morphological analysis and X-ray diffraction (XRD) analysis for the fiber were examined by means of scanning electron microscope (SEM) and X-ray diffractometer. From the results, it has been found that the finite element values are acceptable with proper assumptions, and the prepared natural fiber composite beam material can be used for structural engineering applications.

Image properties of embedded lenses

We give analytic expressions for image properties of objects seen around point mass lenses embedded in a flat $\ensuremath{\Lambda}\mathrm{CDM}$ universe. An embedded lens in an otherwise homogeneous universe offers a more realistic representation of the lense's gravity field and its associated deflection properties than does the conventional linear superposition theory. Embedding reduces the range of the gravitational force acting on passing light beams thus altering all quantities such as deflection angles, amplifications, shears and Einstein ring sizes. Embedding also exhibits the explicit effect of the cosmological constant on these same lensing quantities. In this paper, we present these new results and demonstrate how they can be used. The effects of embedding on image properties, although small, i.e., usually less than a fraction of a percent, have a more pronounced effect on image distortions in weak lensing where the effects can be larger than 10%. Embedding also introduces a negative surface mass density for both weak and strong lensing, a quantity altogether absent in conventional Schwarzschild lensing. In strong lensing, we find only one additional quantity, the potential part of the time delay, which differs from conventional lensing by as much as 4%, in agreement with our previous numerical estimates.

Deflection properties of a MEMS optical scanner with four torsion beams and L-shaped arms

A structural design of a micro-electromechanical-system (MEMS) optical scanner with four torsion beams and arms was investigated to improve the optical scanning properties. Scanners described in previous reports had two pairs of beams and straight arms. In this study, the arm structure was examined without increasing the chip size of the scanner, and the L-shaped arm design was investigated by running simulations and evaluating fabricated samples.The measured resonant frequencies decreased with decreasing connection arm width and agreed with those of the simulation results. The hysteresis of the frequency response at a large deflection was reduced by approximately one half in the L-shaped arm structure as compared to that within the straight arm structure when the connection arm width was designed so that the resonant frequencies of each arm were equal. The optical beam deflection of the L-shaped arm structure for an applied voltage of 2 Vp-p was 20% higher than that for the straight arm structure when the connection arm width was over 800μm. These results indicate that the L-shaped arm structure decreases the hysteresis range by one half and increases the driving efficiency by 20%, even though the device chip size and the other scanner characteristics remained unchanged from those of the straight arm structure.

Radiopaque Laser Fiber for Holmium: Yttrium-Aluminum-Garnet Laser Lithotripsy: Critical Evaluation

Laser energy has gained widespread use, not only in stone treatment, but also in multiple endourologic procedures such as endopyelotomy and incision of ureteral strictures. Furthermore, laser use gains access to open, laparoscopic, and robot-assisted surgery. Therefore, potential complications, such as fiber breakage and detection of these radiolucent fiber remainders, may become of interest. The aim of this study was to evaluate a prototype of a radiopaque laser fiber that was designed for lithotripsy with a holmium:yttrium-aluminum-garnet laser. A gold-clad 200-μm optical laser fiber was evaluated for its influence on deflection, fiber degradation, as well as radiopaque property in vitro and in vivo. The results were compared with a commercially available 200 μm optical core lithotripsy fiber. The gold-clad prototype fiber showed radiopaque property in vitro as well as in vivo, although high body mass index reduces visibility. Introducing the fiber into a flexible ureteroscope had no influence on deflection properties or the diameter of the fully deflected tip. Fiber burn was considerably low and comparable to that of the standard fiber. The 200 μm optical core gold-cladd fiber prototype offers comparable performance to a commercially available fiber of the same optical core diameter. Radiopaque property was proven in vitro as well as intracorporeally, thereby adding an additional safety feature to laser treatment in endourology as well as in laparoscopic and robotic surgery.

The effects of pad geometry and material properties on the biomechanical effectiveness of 26 commercially available hip protectors

Wearable hip protectors (padded garments) represent a promising strategy to decrease impact force and hip fracture risk during falls, and a wide range of products are currently marketed. However, little is known about how design features of hip protectors influence biomechanical effectiveness. We used a mechanical test system (simulating sideways falls) to measure the attenuation in femoral neck force provided by 26 commercially available hip protectors at three impact velocities (2, 3, and 4 m/s). We also used a materials testing machine to characterize the force–deflection properties of each device. Regression analyses were performed to determine which geometric (e.g., height, width, thickness, volume) and force–deflection properties were associated with force attenuation. At an impact velocity of 3 m/s, the force attenuation provided by the various hip protectors ranged between 2.5% and 40%. Hip protectors with lower stiffness (measured at 500 N) provided greater force attenuation at all velocities. Protectors that absorbed more energy demonstrated greater force attenuation at the higher impact velocities (3 and 4 m/s conditions), while protectors that did not directly contact (but instead bridged) the skin overlying the greater trochanter attenuated more force at velocities of 2 and 3 m/s. At these lower velocities, the force attenuation provided by protectors that contacted the skin overlying the greater trochanter increased with increasing pad width, thickness, and energy dissipation. By providing a comparison of the protective value of a large range of existing hip protectors, these results can help to guide consumers and researchers in selecting hip protectors, and in interpreting the results of previous clinical trials. Furthermore, by determining geometric and material parameters that influence biomechanical performance, our results should assist manufacturers in designing devices that offer improved performance and clinical effectiveness.

Studies on the Deflection Properties of Rice Seedling Mat for Transplanter

Studies on the Deflection Properties of Rice Seedling Mat for Transplanter

Characterizing the effective stiffness of the pelvis during sideways falls on the hip

The force applied to the proximal femur during a fall, and thus hip fracture risk, is dependent on the effective stiffness of the body during impact. Accurate estimates of pelvis stiffness are required to predict fracture risk in a fall. However, the dynamic force–deflection properties of the human pelvis have never been measured in-vivo. Our objectives were to (1) measure the force–deflection properties of the pelvis during lateral impact to the hip, and (2) determine whether the accuracy of a mass-spring model of impact in predicting peak force depends on the characterization of non-linearities in stiffness. We used a sling and electromagnet to release the participant’s pelvis from heights up to 5 cm, simulating low-severity sideways falls. We measured applied loads with a force plate, and pelvis deformation with a motion capture system. In the 5 cm trials peak force averaged 1004 (SD 115) N and peak deflection averaged 26.3 (5.1) mm. We observed minimal non-linearities in pelvic force–deflection properties characterized by an 8% increase in the coefficient of determination for non-linear compared to linear regression equations fit to the data. Our model consistently overestimated peak force (by 49%) when using a non-linear stiffness equation, while a piece-wise non-linear fit (non-linear for low forces, linear for loads exceeding 300 N) predicted peak force to within 1% at our highest drop height. This study has important implications for mathematical and physical models of falls, including mechanical systems that assess the biomechanical effectiveness of protective devices aimed at reducing hip fracture risk.

Vibration of Visco-Elastic Parallelogram Plate with Parabolic Thickness Variation

The main objective of the present investigation is to study the vibration of visco-elastic parallelogram plate whose thickness varies parabolically. It is assumed that the plate is clamped on all the four edges and that the thickness varies parabolically in one direction i.e. along length of the plate. Rayleigh-Ritz technique has been used to determine the frequency equation. A two terms deflection function has been used as a solution. For visco-elastic, the basic elastic and viscous elements are combined. We have taken Kelvin model for visco-elasticity that is the combination of the elastic and viscous elements in parallel. Here the elastic element means the spring and the viscous element means the dashpot. The assumption of small deflection and linear visco-elastic properties of “Kelvin” type are taken. We have calculated time period and deflection at various points for different values of skew angles, aspect ratio and taper constant, for the first two modes of vibration. Results are supported by tables. Alloy “Duralumin” is considered for all the material constants used in numerical calculations

Thermal Effect on Vibration of Clamped Visco-Elastic Rectangular Plate with Parabolic Thickness Variation in Both Directions

The analysis presented here is to study the effect of thermal gradient on the vibration of visco-elastic rectangular plate (having clamped boundary condition on all the four edges) of variable thickness whose thickness varies parabolically in both directions. The effect of linear temperature variation has been considered. A frequency equation of plate has been obtained by Rayleigh-Ritz technique with two terms of deflection function. The assumption of small deflection and linear visco-elastic properties of ‘Kelvin’ type are taken. Deflection and time period corresponding to the first two modes of vibrations for clamped plate have been computed for various combinations of aspect ratio, thermal constants, and taper constants. Numerical computations have been performed for an alloy ‘Duralium’ and the results obtained are depicted graphically.