Straight Taper Research Articles

Reducing repair dimension with variable scarf angles

The increase in composites usage for primary and secondary structural components demands advanced repair techniques such as doubler, multi-step, and scarf to restore a damaged structure to its original design capability. Currently, most scarf repairs employ a straight taper at a typical ratio ranging between 1:20 to 1:60 to attain the original design strength. This paper aims to present a new method for reducing the footprint of scarf repairs by optimizing the taper profile through the composite thickness. Experiments are carried out on scarf repairs with piece-wise linear scarf joints, in which the 0° plies are tapered at two different ratios of 1:30 and 1:20, while the 45° and 90° plies are tapered at a ratio of 1:2. Experimental results show that compared to 1:20 straight scarf, the 1:30/1:2 piece-wise linear scarf can achieve 75% of the tensile strength while reducing the repair size by 60%.

COMOC-MG Stitch: Modification of B-Lynch Suturing Technique to Control Atonic Post-partum Haemorrhage.

The COMOC-MG (Compression Of Myometrium and OCclusion of uterine artery by Dr. Mahesh Gupta), a modified B-Lynch stitch technique, utilized polyglycolic acid double strand suture with 80mm long straight taper point and 50mm half circle round bodied needle. Its dual action of causing hemostatic compression as well as reduced uterine blood flow, in managing PPH is exemplified using 3 cases. The COMOC-MG stitch technique was found to be effective, with fewer complications, in controlling post-partum haemorrhage (PPH). One subsequent full-term pregnancy occurred after 6 years of this surgery. The COMOC-MG stitch technique is a valuable and safe alternative to B-Lynch or other modified B-Lynch suturing techniques for successful management of atonic PPH, while preserving fertility.

Preoperative Canal Bone Ratio is Related to High-Degree Stress Shielding: A Minimum 5-Year Follow-Up Study of a Proximally Hydroxyapatite-Coated Straight Tapered Titanium Femoral Component

BackgroundFew studies have reported risk factors for stress shielding. We sought to evaluate clinical and radiographic outcomes of a proximally hydroxyapatite-coated straight tapered titanium femoral component stem during a minimum 5-year follow-up and identify factors associated with high-degree stress shielding. MethodsA total of 156 total hip arthroplasties (n = 124; 98 women and 26 men; mean age, 56.5 years) with a minimum follow-up period of 5 years were included in the study. Clinical and radiologic measurements at follow-up (range, 5-16.3 years; mean, 10.2 years) were analyzed. ResultsThe mean preoperative Harris Hip Score (HHS) was 56.6, and the mean HHS at the latest follow-up was considerably improved at 86.8. Stress shielding at the latest follow-up was low degree in 136 (87%) hips and high degree in 20 (13%) hips. On average, high-degree stress shielding occurred 9.9 years (5-14 years) after surgery. The results of Cox proportional hazard analysis showed that a canal bone ratio ≥ 0.49 was an independent risk factor for high-degree stress shielding (P = .0075; hazard ratio, 3.981). HHS at the latest follow-up was significantly lower in high-degree stress shielding than in low-degree stress shielding (80.7 and 87.7, respectively; P = .0030). ConclusionPreoperative canal bone ratio ≥ 0.49 is independently associated with high-degree stress shielding. In addition, the number of cases with high-degree stress shielding significantly increased over time during a mean 10-year follow-up.

Experimental Study on Split Hopkinson Pressure Bar Pulse-Shaping Techniques for Concrete

AbstractThe dynamic compressive behavior of concrete is investigated using a Φ74-mm variable cross section straight taper split Hopkinson pressure bar (SHPB) apparatus in this study. In order to reduce and eliminate the waveform dispersion effect, two pulse shaping techniques are adopted to improve the incident wave shape. The two techniques include changing the striker (length, shape) and copper pulse shapers (diameter, thickness, shape). Experimental results show that the pulse shaping effect with the small diameter of copper shaper is better than that of the tapered striker and annular pulse shaper, all of which could reach dynamic stress equilibrium, and reduce the high-frequency oscillation, and achieve constant strain-rate deformation approximately.

Use of nano-droplet-enriched cutting fluid (NDCF) in ultra-precision machining

Nano-droplet-enriched cutting fluid (NDCF) demonstrates a linear spreading rate when measured by a contact angle goniometer. The spreading continues beyond that a conventional goniometer can measure. Such thinness allows NDCF to penetrate deep into the tool-chip and tool-workpiece interfaces to affect the lubrication. In this paper, straight taper cutting was carried out using a single-point diamond tool. By examining the groove machined, the enhancement effect of NDCF on improving the surface roughness, reducing bouncing back, and suppressing form irregularities could be quantified. Without NDCF, form irregularities were found on the surface of the grooves in the nature of random localized upheavals. For shallow cuts, NDCF could stabilize the cutting with a depth of cut (DoC) below 1 μm and down to around 0.75 μm, so that the roundness of the machined groove could be maintained precisely. Whereas for deeper cuts, NDCF was found to be effective in preventing form irregularities and on reducing bounce back for a DoC larger than 1.5 μm. Regarding bounce back, the experimental work revealed that NDCF can prevent form irregularities from occurring when the DoC is beyond 1.5 μm. For those samples machined using a conventional oil lubricant, distorted rebounding with a magnitude as large as 200 nm was not uncommon.

Effect of Taper Ratio at Low Reynolds Number

A low speed wind-tunnel investigation is presented documenting the impact of taper ratio at low Reynolds number. An wing using a S8036 section was tested at and 150,000. Taper ratio was varied from 1 down to 0.2 in 0.2 increments. An analytic prediction method as well as extended numerical lifting line theory incorporating nonlinear section data was implemented to compare with experiment. The experimental results indicated a weak dependence of peak lift to drag ratio on taper ratio for both Reynolds numbers. Surface flow visualization showed the presence of a large laminar transitional bubble on the upper wing surface. The relative extent of the bubble was observed to increase towards the tip region for tapered planforms. Agreement between theory and experiment in terms of lift and drag estimation was good. Planform optimization using the extended numerical lifting line theory indicated that at the test conditions and using the selected airfoil section, a planform that differs from straight taper or elliptic may be most efficient.

Effect of femoral mechanical properties on primary stability of cementless total hip arthroplasty: a finite element analysis

With the goal of increasing the survivorship of the prosthesis and anticipating primary stability problems of new prosthetic implants, finite element evaluation of the micromotion, at an early stage of the development, is mandatory. This allows assessing and optimizing different designs without manufacturing prostheses. This study aimed at investigating, using finite element analysis (FEA), the difference in the prediction of the primary stability of cementless hip prostheses implanted into a <TEX>$Sawbones^{(R)}$</TEX> 4th generation, using the manufacturer's mechanical properties and using mechanical properties close to that of human bone provided by the literature (39 papers). FEA was carried out on the composite <TEX>$Sawbones^{(R)}$</TEX> implanted with a straight taper femoral stem subjected to a loading condition simulating normal walking. Our results show that micromotion increases with a reduction of the bone material properties and decreases with the augmentation of the bone material properties at the stem-bone interface. Indeed, a decrease of the cancellous Young modulus from 155MPa to 50MPa increased the average micromotion from <TEX>$29{\mu}m$</TEX> up to <TEX>$41{\mu}m$</TEX> (+42%), whereas an increase of the cancellous Young modulus from 155MPa to 1000MPa decreased the average micromotion from <TEX>$29{\mu}m$</TEX> to <TEX>$5{\mu}m$</TEX> (-83%). A decrease of cortical Young modulus from 16.7GPa to 9GPa increase the average global micromotion from <TEX>$29{\mu}m$</TEX> to <TEX>$35{\mu}m$</TEX> (+33%), whereas an increase of the cortical Young modulus from 16.7GPa to 21GPa decreased the average global micromotion from <TEX>$29{\mu}m$</TEX> to <TEX>$27{\mu}m$</TEX> (-7%). It can also be seen that the material properties of the cancellous structure had a greater influence on the micromotion than the material properties of the cortical structure. The present study shows that micromotion predicted at the stem-bone interface with material properties of the <TEX>$Sawbones^{(R)}$</TEX> 4th generation is close to that predicted with mechanical properties of human femur.

Simulation of Taper Roll Deviation Rectification Ability in Continuous Annealing Furnace

Running deviation of cold strip affects smooth operation in continuous annealing furnace, and the taper roll technology has positive significance for the prevention of strip deviation. In this paper, a finite element model of cold strip in continuous annealing furnace is established, and it can be used to analysis deviation rectification ability of single taper roll with different conical height and straight section length, double taper roll with different total conical height, straight section length and taper ratio. The calculation results show that the conical height is the most important factor for deviation rectification, and the deviation rectification ability of double taper roll is better than single taper roll. The results provide reference for taper roll optimization design in continuous annealing furnace.

Long-Term Results Using the Straight Tapered Femoral Cementless Hip Stem in Total Hip Arthroplasty: A Minimum of Twenty-Year Follow-Up

We report the first long-term results of a prospective cohort study after total hip arthroplasty using the cementless Bicontact hip stem. Between 1987 and 1990, 250 total hip arthroplasties in 236 patients were performed using the cementless Bicontact hip stem. The average follow-up was 22.8years (20.4–24.8) and average age at index surgery was 58.1years. Eighty-one patients died and 9 were lost to follow-up. We noted 11 stem revisions revealing an overall Kaplan Meier survival rate of 95.0% (CI 95%: 91.1–97.2%). The average Harris Hip Score revealed 81 points (range 24–93). The Bicontact hip stem demonstrated high survival rates despite high ages and osteopenic changes, which are equivalent to other long-term reports of cementless stem fixation.

Design of Spot - Size Converter for optical network

The simplified spot-size convert for optical network has been suggested. We have analyzed the mode field distribution and optimized the spot-size converter using beam propagation method. The designed structure was consisted of straight waveguide and taper waveguide using polymer. The efficiency of the designed spot-size converter was over 99%.

Compact optical fiber curvature sensor based on concatenating two tapers

A low-loss, compact, and highly sensitive optical fiber curvature sensor is presented. The device consists of two identical low-loss fused fiber tapers in tandem separated by a distance L. When the optical fiber is kept straight and fixed, no interference pattern appears in the transmitted spectrum. However, when the device is bent, the symmetry of the straight taper is lost and the first taper couples light into the cladding modes. In the second taper, a fraction of the total light guided by the cladding modes will be coupled back to the fundamental mode, producing an interference pattern in the transmitted spectrum. As the fiber device is bent, visibility of the interference fringes grows, reaching values close to 1. The dynamic range of the device can be tailored by the proper selection of taper diameter and separation between tapers. The effects of temperature and refractive index of the external medium on the response of the curvature sensor is also discussed.

Assessment of Straight Tapered Geometry Approximations of Raked-Tip Wings

DOI: 10.2514/1.36817 Straight tapered geometry approximations to wings with raked tips are presented. Only wings with breaks in the trailing-edgesweep areconsidered. Comparisons aremade withpredictionsfromavortex-lattice code foraseriesof uncambered, untwisted wing planforms with raked tips and10 straight tapered approximations to those planforms. Limited comparisons with experimental data are also shown. Lift-curve slope, aerodynamic center, lateral center of pressure, roll damping and lateral stability are compared for 47 planforms. The most accurate method maintained the area, span, leading-edge sweep, and mean aerodynamic chord of the raked-tip planform, generating a new root and tip chord. Nomenclature  = aspect ratio b = wing span CL� = lift-curve slope Cl� = rolling moment due to sideslip angle (lateral stability) Clp = rolling moment due to roll date derivative (roll damping) cb = chord at sweep break cr = root chord ct = tip chord S = wing area xac = longitudinal position of aerodynamic center, measured from apex ycp = lateral position of center of pressure, measured from centerline � = angle of attack � = taper ratio, ct=cr � = rake angle � = sweep angle Subscripts c=2 = midchord eq = equivalent planform le = leading-edge s = streamwise te = trailing edge

Discussion: “Performance and Optimization Analysis for Fins of Straight Taper with Simultaneous Heat and Mass Transfer” (Kundu, B., and Das, P. K., 2004, ASME J. Heat Transfer, 126, pp. 862–868)

Discussion: “Performance and Optimization Analysis for Fins of Straight Taper with Simultaneous Heat and Mass Transfer” (Kundu, B., and Das, P. K., 2004, ASME J. Heat Transfer, 126, pp. 862–868)

Performance and Optimization Analysis for Fins of Straight Taper With Simultaneous Heat and Mass Transfer

An analytical method based on Frobenius power series expansion has been developed for the performance prediction of fully wet fins. Fins of different geometries, namely, longitudinal, annular and spine having both trapezoidal and triangular profiles have been considered. Unlike dry fins, the efficiency and effectiveness of wet fins depend on the fin base temperature and psychrometric condition of the ambient air. A generalized criterion has been derived for the optimization of wet fins having the above geometries. A method for constructing design curves for the optimum fins has also been discussed.

An analysis of plastic flow through polygonal linearly converging dies: as applied to forward metal extrusion

An approximate method based on the upper bound theory has been presented in order to investigate into non-axisymmetric metal extrusion process. In this approach the deformation region is divided into a finite number of rigid tetrahedral blocks that slides with respect to one another. The proposed method is successfully adapted to the extrusion of T-section bars from round billet through straight taper die. Computation for the upper bound pressure is carried out for various process variables such as area reduction, die angle and interface friction. The theoretical predictions are compared with that of known experimental results and found to be well within engineering accuracy.

Performance analysis and optimization of straight taper fins with variable heat transfer coefficient

In the present paper, the thermal analysis and optimization of straight taper fins has been addressed. With the help of the Frobenius expanding series the temperature profiles of longitudinal fin, spine and annular fin have been determined analytically through a unified approach. Simplifying assumptions like length of arc idealization and insulated fin tip condition have been relaxed and a linear variation of the convective heat transfer coefficient along the fin surface has been taken into account. The thermal performance of all the three types of fin has been studied over a wide range of thermo-geometric parameters. It has been observed that the variable heat transfer coefficient has a strong influence over the fin efficiency. Finally, a generalized methodology has been pointed out for the optimum design of straight taper fins. A graphical representation of optimal fin parameters as a function of heat duty has also been provided.

An analytical study of the effect of dehumidification of air on the performance and optimization of straight tapered fins

An analytical study of the performance and optimization of a cooling and dehumidifying straight taper longitudinal fin has been carried out. Expressions for temperature distribution and heat transfer of the fully wet fins have been determined. Fin effectiveness and fin efficiency for various thermo-geometric parameters have been calculated. The optimum dimensions of such types of fins are also estimated using the Lagrange multiplier technique. The analysis shows that the fin effectiveness and fin efficiency of a fin in the case of condensation are found to be smaller than those without condensation. However, the optimum aspect ratio of wet fin is found to be higher than the optimum dry fin with the identical thermo-physical and geometric parameters. Finally, comparative studies on different types of optimum straight taper wet fins with the same fin volume have also been made.

Effect of die geometry on residual stress level present after bar drawing

A new drawing die designed to reduce the residual stresses in bar after drawing is presented. The die design consists of two consecutive straight taper portions, and the outlet portion has a very small die angle. The marked beneficial effect of adding the outlet portion was predicted by finite element modelling (FEM), and subsequently verified by measuring the residual stresses in drawn bars. The optimum range of the outlet die angle was determined using FEM. The new design requires a slightly longer die length than the conventional one, but it is short enough to be adopted in current production lines.

Upper bound analysis of near-net shaped forging of gear coupling form

A simple kinematically admissible velocity field for three-dimensional deformation in near-net shaped forging of a gear coupling form is analysed which takes account of the profiled teeth chosen kinematically by approximating these as straight taper teeth. The upper bound load and the deformed configurations are predicted by the velocity field at varying punch movements considering differing frictional factors. Experiments were carried out on specimens made of a model material, plasticine at room temperature where talcum powder was used as a lubricant. The theoretical predictions of the forging load and the dimensionless forging pressures are found to be in reasonably good agreement with the experimental results.

Analysis of Straight Tapered Microstrip Transmission Lines---ASTMIC (Computer Program Descriptions)

The program ASTMIC calculates the input impedance of straight tapered microstrip transmission lines terminated with arbitrary loads.