Hollow Aluminum Research Articles

Effect of Baffle-block on Material Flow Velocity during Thin-walled Hollow Aluminum Profile Extrusion

The extrusion process of a thin-walled hollow aluminum alloy profile with small features is simulated by using arbitrary Largrang-Euler(ALE) algorithm based HyperXtrude software.The material flow velocity standard deviation in the exit of the die hole is used as a criterion to evaluate velocity uniformity.By designing a series of baffle-blocks,the material flow velocity and the deformation of extrudate are controlled effectively.Effect of baffle-blocks on velocity uniformity is analyzed and a design method of baffle-blocks is proposed.The simulation results demonstrate that the section shapes of baffle-blocks play a key role in controlling material flow velocity in exit.When baffle-blocks have a reasonable section shape,material flow velocity and the deformation of extrudate can be controlled effectively and qualified profiles can be gained by adjusting height and distance between baffle-blocks and mold hole.In a certain range of the baffle-block’s height,the increase of the height of baffle-block can increase the uniformity of the materials flow velocity effectively.However,the increase of the width of baffle-blocks may not work on the balance of material flow material.

Auditory brainstem response evoked by clicks of an echolocating harbour porpoise approaching a target

Event Abstract Back to Event Auditory brainstem response evoked by clicks of an echolocating harbour porpoise approaching a target Meike Linnenschmidt1*, Magnus Wahlberg1, 2 and Janni Damsgaard-Hansen2 1 University of Southern Denmark, Institute of Biology, Denmark 2 Fjord&Baelt, Denmark During echolocation harbour porpoises emit short ultrasonic clicks. Previous measurements of the auditory brainstem response to emitted clicks and returning echoes have shown that sound emission and hearing are actively modified during echolocation, depending on the echolocation task. In these studies the animal was stationary: To investigate if the modifications of hearing operate differently when the animal is actively approaching a target, we measured the auditory evoked potentials of an actively swimming harbour porpoise while echolocating a target. Two EEG silver disc electrodes submerged into latex suction cups attached to the body surface of the animal picked up the auditory brainstem potentials. A custom build suction cup hydrophone attached on the melon detected the acoustically emitted signals and returning echoes from the target. The target was a hollow aluminium cylinder (target strength -18 dB) and lowered 0.5 m below water surface at 5 m away from the porpoise at the beginning of each trial. A separate custom build hydrophone was attached 3 cm above the target. The animal swam a distance of 5 m parallel to floating pontoons at a depth of about 0.5 m to approach and touch the target. A trainer followed the swim path of the animal to secure the cables. The acoustic signals were amplified (52 to 70 dB) and high pass filtered (10 kHz) and the electric potentials were differentially amplified (80 dB) and band pass filtered between 0.3 and 10 kHz. The overall echolocation pattern was similar to a prey capture, thus including an approach and a buzz phase. The range between the animal and target was calculated by the time delay between the two separately recorded acoustic signals. During the approach phase the auditory brainstem response to the emitted click was evident after averaging 95 consecutive segments of electrode signals around each click. Three prominent electric potential peaks were discernible as a response to click production, similar to what has been previously found as a typical cetacean auditory brainstem response to an emitted echolocation click. This study suggest that auditory brainstem responses evoked by echolocation clicks and echoes can also be obtained from free-moving marine mammals. The harbour porpoise is suitable for such studies, as its auditory brainstem response has such a great signal to noise ratio. Keywords: approach, auditory brainstem response, Echolocation, free-swimming, Harbour porpoise Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for participant symposium and student poster award) Topic: Sensory: Audition Citation: Linnenschmidt M, Wahlberg M and Damsgaard-Hansen J (2012). Auditory brainstem response evoked by clicks of an echolocating harbour porpoise approaching a target. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00206 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 29 Apr 2012; Published Online: 07 Jul 2012. * Correspondence: Miss. Meike Linnenschmidt, University of Southern Denmark, Institute of Biology, Odense M, 5230, Denmark, meike.linnenschmidt@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Meike Linnenschmidt Magnus Wahlberg Janni Damsgaard-Hansen Google Meike Linnenschmidt Magnus Wahlberg Janni Damsgaard-Hansen Google Scholar Meike Linnenschmidt Magnus Wahlberg Janni Damsgaard-Hansen PubMed Meike Linnenschmidt Magnus Wahlberg Janni Damsgaard-Hansen Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Behavior of Lateral Resistance of Flexible Piles in Layered Soils

This paper presents an experimental investigation on the lateral load carrying capacity of model piles of different flexural stiffness embedded in loose sand between dense sand and dense sand between loose sand layered soil strata. Attempts has been made to study the variation of lateral stiffness, eccentricity and soil layer thickness ratio and the effect of various parameters on the magnitude of Nh. The result of a model tested for the piles embedded in IS grade-II dry Ennore sand under monotonic lateral loadings. Experimental results are used for the load-deflection curves (p-y curves) for laterally loaded piles. The proposed p-y curves were compared to the existing curves with Nh and were evaluated with the experimental data. The ultimate lateral soil resistance and subgrade modulus were investigated and discussed. 0 for dense condition. The tests were conducted in two steps. a) The soil condition is loose sand layer between dense sand layer with H/D ratio of 0.25, 0.50, 0.75, and 0.90. b) The soil condition is dense sand layer between loose sand layer with H/D ratio of 0.25, 0.50, 0.75,and 0.90, where H is the thickness of middle layer and D is the total depth of embedment of the pile(=300mm). In both the cases the eccentricities of 0, 50, 100, 150 and 200mm are conducted in homogeneous loose sand layer and dense sand layer. The outside diameters of the piles are 16mm for solid Steel and Wooden Piles. Hollow Aluminium pile with 16mm outside and 0.3mm thickness. The embedment depths of all the piles are 300mm. The flexural rigidity of steel, wooden and Aluminium piles were 642.106Nm 2 , 506.12Nm 2 and 51.041Nm 2 respectively. The relative stiffness factors for steel, wooden and Aluminium were 0.1192, 0.939 and 0.0094 respectively for Loose sand layer and 0.0263, 0.0207 and 0.0020 for Dense sand layer. The horizontal displacement and rotation of pile cap are recorded by L.V.D.T. and two dial gauges. The stabilized 'Rainfall-Technique' this standard technique is available in standard literature and this technique was used to pour the sand in the testing steel tank. Figure.1 shows schematic sketch of experimental setup.

Finite Element Modelling in Ultrasonic Sheet Metal Forming

Finite element (FE) model of die necking process of an aluminium hollow thin cylinder has been developed. The input parameters of material properties and coefficient of friction, µ for the model have been deducted from our previous experimental study. Later the models have been validated against experimental data as reported in the previous studies. For the die necking process, the FE model has successfully to predict how much the original diameter of the aluminium hollow cylinder can be maximised necked with and without applying ultrasonic vibration. FE models showed that the application of ultrasonic vibration during the necking process has reduced buckling of the cylinder body if compared to the necking process without ultrasonic. The benefit of applying ultrasonic vibration in sheet metal forming process has been related to the reduction of interface friction between die and specimen.

The Chimeric Approach Reveals That Differences in the TRPV1 Pore Domain Determine Species-specific Sensitivity to Block of Heat Activation

The capsaicin-, heat-, and proton-activated ion channel TRPV1, a member of the transient receptor potential cation channel family is a polymodal nociceptor. For almost a decade, TRPV1 has been explored by the pharmaceutical industry as a potential target for example for pain conditions. Antagonists which block TRPV1 activation by capsaicin, heat, and protons were developed by a number of pharmaceutical companies. The unexpected finding of hyperthermia as an on-target side effect in clinical studies using polymodal TRPV1 antagonists has prompted companies to search for ways to circumvent hyperthermia, for example by the development of modality-selective antagonists. The significant lack of consistency of the pharmacology of many TRPV1 antagonists across different species has been a further obstacle. JYL-1421 for example was shown to block capsaicin and heat responses in human and monkey TRPV1 while it was largely ineffective in blocking heat responses in rat TRPV1. These findings suggested structural dissimilarities between different TRPV1 species relevant for small compound antagonism for example of heat activation. Using a chimeric approach (human and rat TRPV1) in combination with a novel FLIPR-based heat activation assay and patch-clamp electrophysiology we have identified the pore region as being strongly linked to the observed species differences. We demonstrate that by exchanging the pore domains JYL-1421, which is modality-selective in rat can be made modality-selective in human TRPV1 and vice-versa.

Effect of extrusion stem speed on extrusion process for a hollow aluminum profile

Extrusion stem speed is one of important process parameters during aluminum profile extrusion, which directly influences the profile quality and choice of extrusion equipments. In this paper, the extrusion process of a thin-walled hollow aluminum profile was simulated by means of the HyperXtrude commercial software. Through a serial of numerical simulation, the effects of stem speed on extrusion process, such as metal flow behavior at die exit, temperature distribution, extrusion force, and welding pressure, have been investigated. The numerical results showed that there existed an optimum value of stem speed for flow velocity distribution. With the increasing stem speed, the temperature of the extrudate and required extrusion force increased, and the welding quality of extrudate would be improved. Through comprehensive comparison and analysis, the appropriate stem speed could be determined for practical extrusion production. Thus, the research results could give effective guideline for determining initial billet and die temperature and choosing the proper extrusion press in aluminum profile industry.

Numerical simulation and metal flow analysis of hot extrusion process for a complex hollow aluminum profile

The most important way to improve the quality of aluminum profiles is to assure the material flow through die land exit with the same velocity. In this paper, a numerical model was developed to investigate metal flow behavior during aluminum profile extrusion. Firstly, the numerical model for a complex hollow aluminum profile was built based on the arbitrary Lagrangian–Eulerian program HyperXtrude. Then, with the numerical model, metal flow behavior at each stage during the whole extrusion process was analyzed and dead zones in the die cavity were also investigated by means of the particle tracking method. Finally, the numerical results were validated by comparing with the nose ends of two extrudates in practice, and the comparison showed that the numerical model developed in this work could provide the effective guidance for practical production.

Dynamic tests of cemented paste backfill: effects of strain rate, curing time, and cement content on compressive strength

This article investigates the compressive strength of cemented paste backfill (CPB) under dynamic loading. To accommodate the low impedance CPB, a modified split Hopkinson pressure bar (SHPB) system is adopted. In contrast to traditional solid steel transmitted bar, a hollow aluminum transmitted bar is introduced to reduce the impedance. With this system, the dynamic stress equilibrium is achieved, which guarantees the valid dynamic material testing condition. The dynamic tests are conducted for CPB with different cement contents and curing time. It is observed that: (1) for CPB with the same curing time and cement content, the dynamic strength increases with the strain rate, (2) for CPB with the same cement content, the dynamic strength increases with the curing time, and (3) for CPB with the same curing time and tested under similar strain rate, the dynamic strength increases with the percentage of cement. This observation can be understood by considering the hydration process of cements.

Collapse behavior evaluation of hybrid thin-walled member by stacking condition

The recent trend of vehicle design aims at crash safety and environmentally-friendly aspect. For the crash safety aspect, the energy absorbing members should absorb collision energy sufficiently but for the environmentally-friendly aspect, the vehicle structure must be light weight in order to improve the fuel efficiency and reduce the tail gas emission. Therefore, the light weight of vehicle must be achieved in a securing safety status of crash. An aluminum or carbon fiber reinforced plastics (CFRP) is representative one of the light-weight materials. Based on the respective collapse behavior of aluminum and CFRP member, the collapse behavior of hybrid thin-walled member was evaluated. The hybrid members were manufactured by wrapping CFRP prepreg sheets outside the aluminum hollow members in the autoclave. Because the CFRP is an anisotropic material whose mechanical properties, such as strength and elasticity, change with its stacking condition, the effects of the stacking condition on the collapse behavior evaluation of the hybrid thin-walled member were tested. The collapse mode and energy absorption capability of the hybrid thin-walled member were analyzed with the change of the fiber orientation angle and interface number.

Refining a Nordmøre-grid for a Brazilian artisanal penaeid-trawl fishery

Two experiments were done to assess and refine the Nordmøre-grid in a canoe-trawl fishery targeting Xiphopenaeus kroyeri off southern Brazil. During experiment 1, a codend containing a small (1881 cm 2) Nordmøre-grid (24-mm bar spaces) retained significantly less total bycatch (mean predicted weight reduced by 56%), brachyurids (by 79%) and teleosts (by 50%) than a conventional configuration (control), without significantly affecting the weights or numbers of X. kroyeri, although mean predicted weights were 12% lower. During experiment 2, the bar spaces were subsequently maintained, but the grid area was increased by 1.4 while the extension section mesh size was reduced by 1.3, and the impacts of different materials (hollow vs. solid aluminium rod), bar diameter (10 vs. 16 mm) and presence/absence of a guiding panel were investigated. Most of these technical changes had minimal effects, with all grid configurations maintaining catches of X. kroyeri (at between −13 and +22% of the control) and significantly reducing total bycatch (up to 54%) and brachyurids (up to 90%). But, unlike the small grid, none of the large grids significantly reduced the catches of teleosts. This result was attributed to the increased distance required by fish smaller than the bar spaces to swim out of the escape exit. While ongoing refinements, including narrower bar spaces, could improve the performance of the Nordmøre-grid, the results justify the adoption of the generic configuration as a means for improving selectivity in this fishery.

High efficiency coupling of Terahertz micro-ring quantum cascade lasers to the low-loss optical modes of hollow metallic waveguides

We demonstrate that azimuthally polarized surface emitting Terahertz quantum cascade lasers fabricated in a micro-ring resonator geometry can be coupled to cylindrical hollow aluminum waveguides reaching efficiencies as high ≈98%, when a collimating lens is used. By placing the waveguide in close contact with the QCL in a simple back-to-back geometry, the laser mode can be perfectly matched with the low loss TE(01) waveguide mode showing attenuation losses as low as ≈2.3-2.7 dB/m at 3.2 THz.

Effects of Multi-Step Welding Chamber on Extrusion Product Quality and Die Strength

The shape of welding chamber is a key parameter in flat porthole die extrusion process, which influences product quality and die life-span directly. In this paper, by means of numerical simulation of the extrusion process for an aluminum hollow profile, the effects of multi-step welding chamber on metal flow and die strength have been investigate. The numerical results revealed that the multi-step welding chamber was effective to balance metal flow in the die cavity. In addition, with an increasing step of welding chamber, the maximum stress and deflection of the lower die decreased, while the deflection of the mandrel kept almost unchanged and the maximum stress of upper die increased.

Decreased echolocation performance following high-frequency hearing loss in the false killer whale (Pseudorca crassidens)

Toothed whales and dolphins possess a hypertrophied auditory system that allows for the production and hearing of ultrasonic signals. Although the fossil record provides information on the evolution of the auditory structures found in extant odontocetes, it cannot provide information on the evolutionary pressures leading to the hypertrophied auditory system. Investigating the effect of hearing loss may provide evidence for the reason for the development of high-frequency hearing in echolocating animals by demonstrating how high-frequency hearing assists in the functioning echolocation system. The discrimination abilities of a false killer whale (Pseudorca crassidens) were measured prior to and after documented high-frequency hearing loss. In 1992, the subject had good hearing and could hear at frequencies up to 100 kHz. In 2008, the subject had lost hearing at frequencies above 40 kHz. First in 1992, and then again in 2008, the subject performed an identical echolocation task, discriminating between machined hollow aluminum cylinder targets of differing wall thickness. Performances were recorded for individual target differences and compared between both experimental years. Performances on individual targets dropped between 1992 and 2008, with a maximum performance reduction of 36.1%. These data indicate that, with a loss in high-frequency hearing, there was a concomitant reduction in echolocation discrimination ability, and suggest that the development of a hypertrophied auditory system capable of hearing at ultrasonic frequencies evolved in response to pressures for fine-scale echolocation discrimination.

Deformation conditions in the extrusion weld zone when using pointed and square ended bridge

In porthole extrusion of hollow aluminium profiles metal streams flow around the die bridges and re-join in the welding chamber behind the bridges through the process of solid state bonding creating an extrusion weld. The welding process is of complex nature and it is required to understand the deformation phenomena present in the region where the seam weld is created. New knowledge of metal deformations when the metal joins behind a die bridge is obtained in our study performed in a simple 2D die arrangement. When two metal streams joins behind the bridge the material flow here is influenced by the design of the die bridge. In the current study the extrusion welding process have been compared when using butt or pointed rear end shape of the bridge. The main focus has been on the region behind the bridges where the metal streams join and welding takes place. The location of the dead zones and their effect on the characteristics of material flow are investigated. A quantitative analysis of the pressure build-up along the weld is performed. The extensions of the interfacial layer which makes up the seam weld are quantified. The conditions of strain rate in the welding zone are compared for bridges with square and pointed rear end. A “stretching zone” has been identified behind the two types of bridges. In this zone there is high strain rate and the deformations here are quantitatively compared in the study. The work contributes to better understanding of the mechanisms by which extrusion welding takes place. Finite element modeling has extensively been used while an experimental grid pattern technique has been used to secure good agreement between simulation and experiments. In simulation the grid pattern technique has also been used to investigate the deformation of the metal as it flows through the stretching zone.

Development of CAD System and Forming CAE of Porthole Extrusion Moulds for Hollow Aluminum Profile

According to the design principles and structure characters of the plane porthole extrusion moulds of hollow aluminum profiles, the general structure of a UG based CAD system for porthole extrusion moulds of aluminum profiles is designed after system analysis and plan, by adopting the object oriented technology and OMT (Object Modeling Technology) methods. Then the CAD system is developed based on UG software with the help of UG / Open GRIP re-developing tools. The sample design approved that it is quite convenient to design parametric porthole extrusion moulds CAD model by using the developed CAD system. In the last part, the FVM (Finite Volume Method) is used to simulate the process of extrusion. The metal flow, the equivalent stress distribution are analyzed for future optimization of the porthole structure.

Dynamic behavior of small-scale model of nailed steep slopes

This paper presents the results of laboratory shaking table tests performed to study the dynamic behavior of reinforced steep slopes. The surface displacements, settlement of the crest and acceleration responses along with strain behavior of the facing wall are examined during the tests. Two 18-cm high steep slopes with slope angles of 60° and 70° are considered. Each slope is reinforced with nine number of hollow aluminum nails placed in three rows. Each nail is glued with three strain gauges to measure the tensile force developed in the nails. Four strain gauges are fixed at the center of the facing wall to measure the development of strains during shaking. The acceleration responses at the base and crest of the model slopes are monitored during the test durations. The numerical simulation of the model tests is performed by a commercial program called FLAC. The numerical results are found to be reasonable close to the corresponding experimental results.

Hollow castings produced by interrupted low pressure die casting

Hollow aluminium castings have been produced by low pressure die casting where the pressure has been released when only a shell has solidified, thereby draining the liquid out of the centre of the casting. The influence of holding time of the melt in the die, the die temperature and the alloy type on the thickness and quality of the solidified shell has been investigated. It has been found that hollow castings can be produced reproducibly with constant wall thickness under constant process conditions. The casting wall thickness increases linearly with pressure holding time. The die temperature has less influence on the wall thickness. The roughness of the inner surface of the castings varies with alloy type. An Al–12 wt-%Si (AlSi12) alloy gives a very uneven rough inner surface whereas an Al–5 wt-%Mg (AlMg5Si) alloy gives a smooth, even surface. Grain refinement also improves the surface quality. Attempts to predict the wall thickness with a commercial casting software package had limited success; the calculations seem to overestimate the thickness.

Numerical Simulation of Extrusion Process and Die Structure Optimization for a Hollow Aluminum Profile with Thin Wall

The extrusion die plays a crucial role in the quality control of aluminum alloy profile production.Yet in practice,the design of extrusion die is mainly dependent on the experience and intuition of the designer,thus many times of modifications and experiments are needed to gain an acceptable product.The extrusion process of a complex hollow aluminum alloy profile is simulated by using ALE algorithm based HyperXtrude software,and the flow behavior of material and deformation mechanism in the die cavity are investigated.With the simulation results of the initial die design scheme,a non-uniform velocity distribution is observed.Thus two optimization schemes(establishment of double-step welding chamber at lower mold and introduction of baffle plate) are proposed to solve the problem.In addition,with the optimal die structure,the temperature and stress distribution in the cross-section of the profile become more even and the weld quality is also improved.The feasibility of die design and optimization method based on numerical simulation is validated,which can provide theoretical guidelines for the die design of the same kind profile.

Acoustic band gaps in finite-sized two-dimensional solid/fluid phononic crystals

Acoustic band gaps in two-dimensional phononic crystal consisting of a finite-sized square array of parallel hollow aluminum cylinders in air are investigated with the finite difference time domain (FDTD) method. Experimental measurements were carried out to validate the theoretical predictions with excellent overall agreement achieved. The numerical method is used subsequently to study the band gap properties of phononic crystals composed of cylinder (both solid and hollow)/fluid systems for two different acoustic impedance ratios. For both types of system, the influence of the transverse size of the phononic crystal on the propagation properties is analyzed, and the minimum size to achieve the largest band gap width for different filling factors is determined.

J0201-1-5 中空アルミ押出形材を用いたクラッシュボックスの圧壊特性([J0201-1]自動車の衝突と傷害の力学(1))

J0201-1-5 中空アルミ押出形材を用いたクラッシュボックスの圧壊特性([J0201-1]自動車の衝突と傷害の力学(1))