Metal Connector Research Articles

GFRP 보강적층판 및 GFRP rod를 이용한 낙엽송 집성재 접합부의 모멘트저항 성능평가

Instead of metal connector generally used on the structural glued laminated timber rahmen joints, the GFRP reinforced laminated plates combining veneer and GFRP (Glass Fiber Reinforced Plastic) and bonded type GFRP rod were used as the connectors. As a result of moment resistance performance evaluation on the joint part applied with these connectors, the yield moment of specimen using the GFRP reinforced laminated plates and GFRP rod pin was measured 4 % lower in comparison to the specimen (Type-1) using the metal connectors, but the initial rotational stiffness was measured 29% higher. Also, the yield moment and rotational stiffness of the specimen using the GFRP-reinforced laminated plates and wood (Eucalyptus marginata) pin showed were measured 11% and 56% higher in comparison to the Type-1 specimen, showing the best performance. It was also confirmed through the failure shape and perfect elasto-plasticity analysis that it showed ductility behavior, not brittle fracture, from the shear resisting force by the pin and the bonding strength increased and the unification of member was carried out. On the other hand, in case of the specimen bonded with GFRP rod, it was impossible to measure the bonding performance or it was measured very low due to poor bonding.

Damage Detection for Curved Surfaces Using Advanced Piezo Impedance Transducers

In recent years, it is necessary to monitor every civil and mechanical structure for the safety of human life and property. By using PZT, monitoring of structures is possible with some limitations such as direct attachment to the host structure, structure subjected to impact from external forces, inaccessible structure, high temperature locations, and structures with complex geometry and curved surfaces. To overcome these limitations, a new technique is employed for structural health monitoring. Using the advanced technique, transducer is prepared by attaching PZT with metal connectors which is in turn attached to the monitored structure. This paper demonstrates experimental study on mild steel pipes. Different aspects of SHM are studied. The proposed technique effectively detects locations of damages and severity of damages of pipe specimen. The technique is also employed to study effect of temperature variation along with detecting progressive damage of pipe specimen when it is subjected to steady constant high temperature. This technique is applicable to high temperature locations as the temperature of PZT maintained below its Curie temperature by introducing metal connector between structure and PZT patch. For the quantification of damages, the RMSD index formula is used.

Dogged Persistence: Harrington, Post-polio Scoliosis, and the Origin of Spine Instrumentation by Marc A. Asher

Reviewed by: Dogged Persistence: Harrington, Post-polio Scoliosis, and the Origin of Spine Instrumentation by Marc A. Asher Daniel J. Wilson Marc A. Asher. Dogged Persistence: Harrington, Post-polio Scoliosis, and the Origin of Spine Instrumentation. Traverse City, Mich.: Chandler Lake Books, 2015. xx + 395 pp. Ill. $30.00 (978-1-943338-01-6). Marc Asher’s Dogged Persistence is both a biography of Dr. Paul Harrington and a history of the development of his system of spine instrumentation designed to correct scoliosis. Harrington was one of the first surgeons in the post–World War II era to invent, manufacture, and use a system of metal rods to correct moderate to severe spinal curvatures. The existing system of using body casting to straighten the spine and maintain stability following a fusion of the vertebrae involved long periods of immobility and had a high failure rate. Harrington was convinced that he could design metal rods and connectors that could straighten and hold the spine in place with or without an accompanying fusion and without lengthy immobilization. Developing this procedure and instrumentation involved many years of trial and error and overcoming the resistance of his fellow orthopedic surgeons before spine correction using implanted instrumentation became commonplace in the 1960s. Harrington was born in Kansas City, Kansas, in 1911. Educated in the public schools of Kansas City, he was also a standout athlete in basketball and track. He later graduated from the University of Kansas and its medical school. Following graduation, he entered an orthopedic residency in Kansas City with the ambition of becoming “the top in orthopedic surgery” (p. 38). During World War II he served as a surgeon in an evacuation hospital in North Africa and in Europe following D-Day. After the war, Harrington and his wife moved the family to Houston where Harrington joined the newly created Texas Medical Center. He remained in Houston for the rest of his career and died there on November 29, 1980. [End Page 568] The polio epidemics of postwar America resulted in a significant increase in the number of young patients who developed scoliosis as the result of paralyzed or weakened muscles of the torso. Very involved in the care of polio patients in the Houston hospitals, Harrington by the early 1950s had developed a theory to support his evolving ideas on scoliosis treatment. Placing a great deal of emphasis on what he called the “dynamic stability and dynamic balance” (p. 98) of the spine, he designed his instruments to restore that balance. Asher devotes considerable attention to the details of Harrison’s efforts over two decades to design effective rods and connectors and then to modify them based on his experience in the operating room. Asher’s descriptions are helpfully supplemented by many of Harrington’s drawings of the instrumentation. Harrington’s extensive correspondence with Zimmer Manufacturing describes these changes in some detail and portrays the close collaboration as the company worked with the orthopedist to manufacture instrumentation to his specifications. Asher also recounts ways in which Harrington’s rods went from being an experimental instrumentation to an accepted technique in orthopedic spine surgery. Harrington’s rods and procedures initially met significant resistance from other surgeons, and Asher details Harrington’s efforts through publications and presentations to win acceptance for his methods. In addition, Asher describes in detail the creation of the Scoliosis Research Society in which Harrington was a charter member. Asher provides a detailed account of Harrington’s career and surgical innovations, but the reader is sometimes overwhelmed by minute changes in instrument specifications and by summaries of numerous orthopedic conference presentations. Some of this material could have been summarized. The book would also have been stronger had Asher given attention to the patients’ perspectives. It would have been helpful to know, for example, how patients regarded Harrington and how they responded to his surgical interventions. There are apparently patient letters in the Harrington papers, but Asher makes almost no use of them. Dogged Persistence is a traditional medical biography in which Asher emphasizes Paul Harrington’s career and the development of his innovative spinal instrumentation and surgery. Asher concludes that Harrington’s achievement was a significant advance in treating...

Repair of Partially Embedded Metal Connector Plates

Abstract Partially embedded metal connector plates can occur in wood trusses when the plates are not properly pressed, when they “walk out” as the wood dries during service, or when there is a mismatch in member thickness. Current industry practice is to ignore the remaining strength of a partially embedded plate when making repairs. This assumption results in a large, overdesigned repair along with high material and labor costs. The project objective was to determine if a smaller clamped repair is sufficient to restore the strength of the partially embedded plate to the fully embedded connection strength. A total of 40 tension splice connections were fabricated from 2 by 6 members with 5 by 3 metal connector plates. The specimens included 10 fully embedded plates, 10 partially embedded plates, 10 partially embedded plates repaired with plywood gussets secured outside of the main 2 by 6 members (RC), and 10 partially embedded plates repaired with plywood gussets and light wood screws (RS). The average strength of the partially embedded RC specimens and partially embedded RS specimens were 87 and 108 percent of the fully embedded specimens' strength, respectively, whereas the unrepaired partially embedded plates achieved only 60 percent of the fully embedded specimens' strength. The results of the tests indicate that smaller screw-type gusset repairs are sufficient to return the strength of a tensile splice connection with a 1/16-inch partially embedded plate to its fully embedded plate capacity. Both the clamping action of the plywood gussets and the additional tensile capacity of the screwed plywood gussets were observed to contribute to the strength gains.

FRP 보강적층판의 접착성능 및 파괴인성평가

목구조물 접합부에 기존의 슬릿(slit)형 강판을 대체하기 위해서 FRP (Fiber Reinforced Plastic) 보강적층판을 제작하였다. 보강재, 접착제 종류에 따라 총 4가지 타입의 FRP 보강적층판을 제작하였으며, 접합부 적용 전 KSF 3021과 KSF 2160에 의거한 박리실험과 ASTM D5045-99에서 제안한 Compact Tension (CT)형 파괴인성 시험을 실시하였다. 접착성능 시험결과 GFRP textile, GFRP sheet, GFRP Textile-Sheet 타입의 FRP 보강적층판은 침지 및 내수침지박리 시험에서 모두 KS 기준인 박리율 5% 이하를 만족하였다. 그러나 Aramid 타입의 시험편은 침지박리율 4.8%로 기준을 만족하였으나 내수침지박리율 70%로 합격기준을 만족하지 못하였다. 파괴인성 시험결과 단판만을 교차적층 시킨 대조군시험편보다 목재 대비 보강재 체적비를 23%로 함으로서 FRP 보강적층판의 내력이 2~4배 증가하였다. 그중에서도 GFRP Textile-Sheet 타입의 시험편이 하중 평행방향의 유리섬유 배열로 인해 할렬파단을 억제하면서 대조군 대비 응력확대계수 비가 61% 증가되어 파괴를 가장 크게 억제하는 것으로 확인되었다. FRP 보강적층판과 비금속 dowels을 사용한 접합부의 인장형 전단내력은 금속접합에 비해 약 12% 낮은 내력이 측정되었다. In order to replace existing slit type steel plate on the wooden structure joint, the FRP-reinforced laminated plates were produced. Four types of FRP-reinforced laminated plates were produced according to the type of reinforcement and adhesive, and before applying to the joint, the adhesion performance test according to KSF 3021 and KSF 2160 and the Compact Tension (CT) type fracture toughness test specified in ASTM D5045-99 were carried out. As a result of adhesion performance test, all GFRP textile, GFRP sheet, and GFRP Textile-Sheet type FRP-reinforced laminated plates satisfied the requirement of soaking delamination percentage with smaller than 5% based on KS standard. However, aramid type specimen satisfied the standard as the soaking delamination percentage of 4.8% but it did not satisfied the standard as the water proof soaking delamination percentage of 70%. As a result of fracture toughness test, the volume ratio of reinforcement to timber became 23% so that the strength of FRP-reinforced laminated plates increased by two to four times in comparison to the control specimen. It was confirmed that the GFRP Textile-Sheet type specimen was most resistant to the fracture most since the ratio of stress intensity factor compared with that of the control increased to 61% owing to the parallel arrangement of glass fiber to the load. As a result of tensile shear strength test using FRP-reinforced laminated plates and nonmetal dowels, it is about 12% lower than metal connectors.

Fire performance of metal-free timber connections

The fire performance of heavy timber frame structures is often limited by the poor fire performance of its connections. Conventional timber connections, dowelled or toothed plate connections typically use steel as a connector material. In a fire, the steel parts rapidly conduct heat into the timber, leading to reduced fire performance. Replacing metallic connectors with alternative non-metallic, low thermal conductivity connector materials can, therefore, lead to improved connection performance in fire. This paper presents an experimental study into the fire performance of metal-free timber connections comprising a hot-pressed plywood flitch plate and glass-fibre-reinforced polymer dowels. The thermal behaviour of the connections at elevated temperatures is studied using a standard cone calorimeter apparatus and a novel heat transfer rate inducing system. The latter is a fire testing system developed at the University of Edinburgh. The mechanical behaviour of the connection during severe heating was also studied using an environmental chamber at temperatures up to 610°C. The results demonstrate that heat transfer in the non-metallic connections is governed by the thermal properties of the timber, resulting in significant enhancements in connection fire performance.

Innovative Experimental Techniques in the Service of Restoration of Stone Monuments - Part I: the Experimental Set up

The mechanical response of marble epistyles interconnected to each other by means of metallic connectors when subjected to shear loading is studied experimentally. The study is motivated by the need of the scientific group of the Athenian Acropolis to substitute damaged ancient connections by new ones. In this direction “I”-shaped titanium connectors are placed in the grooves sculptured by ancient stonemasons in the marble blocks and the empty space is then filled by a suitable cement-based material. Guided by the experience gathered from the inspection of failed connections, which clearly indicates that failure starts at the interior of the “titanium-mortar-marble” complex, along the material interfaces, an experimental protocol was improvised, aiming at pumping data from the interior of the interconnected epistyles. For this to be accomplished innovative sensing techniques like pressure stimulated currents, digital image correlation and acoustic emission were used in conjunction with traditional ones. In the first part of this short two-paper series the experimental set-up, the materials and the specimens’ geometry are described.

Metal connector plate - experimental determination of plate anchorage capacity

Metal connector plate - experimental determination of plate anchorage capacity

Interconnected Epistyles of Marble Monuments Under Axial Loads

The restoration of destroyed connections of epistyles joined together by means of metallic connectors is among the most difficult problems encountered by scientists working for the conservation/restoration of monuments made of marble. The complexity of the geometry and the interaction of three completely different materials (metal-filling material-marble) constituting the connection render the study (either experimental or analytic) extremely complicated. In this direction a numerical analysis is presented here in order to deeply understand the response of a typical ancient connection subjected to axial loads as well as to quantify the influence of some geometric parameters on its response. The parameters studied include the length of the connector, the width of its flanges, the depth of the groove (mortise), the existence or not of relieving space and the filling material’s volume. The numerical model was calibrated and validated according to the results of an earlier experimental study realized on the worksite of the Parthenon Temple. It was concluded that the interventions required to relieve the stress field by changing the size of the connector are disproportional to the respective positive effect on the response of the connection. Moreover it was proved that the most beneficial parameter is the relieving space.

Experimental Characterization of Monotonic and Cyclic Loading Responses of CLT Panel-To-Foundation Angle Bracket Connections

AbstractCross laminated timber (CLT) is an engineered wood plate product suitable for the construction of shear walls in low-rise and medium-rise residential and commercial buildings. CLT shear walls are attached to foundations by using metal connectors arranged to prevent the horizontal sliding and uplift of entire superstructures. It is critical that individual CLT panels remain properly anchored, even during events such as design level wind storms and earthquakes, and that overloaded connectors attaching walls to foundations are capable of deforming plastically. This paper presents an experimental investigation of the mechanical behaviors of a range of commercially manufactured and specially designed steel angle bracket connectors intended to resist horizontal shear force flow at CLT wall and foundation interfaces. Both monotonic loading and fully reversed displacement controlled loading protocols were employed so that results apply to wind and seismic design scenarios. The broad conclusion is that the...

Kinetic Assembly of a Thermally Stable Porous Coordination Network

The advantage of porous coordination network synthesis is designability by changing metal sources and ligands.[1] Therefore, not only many commercially available ligands but also newly synthesized ones were used for networking. On the other hand, most of metal sources are common reagents or stable metal moieties because they can be more predictable as a metal connector. So far, there is no report focusing on usage of labile metal sources for selective network formation. One of the promising methods to produce unique networks with such labile metal sources is kinetic control[2] because labile metal sources produce various species in solution. In this talk, we will introduce selective syntheses of thermally stable porous coordination networks using a labile Cu4I4 cubane cluster [Cu4I4(PPh3)4] (1) and a rigid tetradentate Td-symmetry ligand tetra-(4-(4-pyridyl)phenyl)methane (2) by kinetic and thermodynamic control.[3] On heating the mixture of 1 and 2 in DMSO at 453 K, a homogenous colorless solution was obtained. Rapid cooling (~20 Kmin-1) of the solution produced yellow needle crystals, {[(CuI)2(2)]·solvent}n (3a) that shows novel CuI helical chain unit, in 99% yield (Fig. A). On the other hand, slow cooling (~3 Kmin-1) produced orange block crystals, {[(Cu2I2)(2)]·solvent}n (3b) that shows rhombic Cu2I2 dimer unit, in 95% yield. Both the network crystals can keep the crystallinity up to 673 K under N2 atmosphere. In kinetic product 3a, due to the unique structure, iodides of the CuI chains facing to 1D channel, the network crystal shows chemisorption of I2 by making a covalent bond with an iodide of part of the CuI chains to form an I3– group (Fig. B). On the other hand, in thermodynamic product 3b, Cu2I2 dimer units are hindered by bridging ligand 2. That is why network crystal 3b shows only physisorption of I2, even though network has 1D channel similar to 3a.

GFRP보강적층목재핀의 휨강도 및 인장형 전단내력 성능평가

By replacing the previous metal connector on the joints of timber structure, the GFRP reinforced laminated wooden pin was produced using a wooden material and Glass fiber reinforced plastic(GFRP) composite laminate. In addition, using the reinforced wooden pin, the tensile type shear strength test was conducted. Based on the result of the bending strength test of the reinforced laminated wooden pin according to the GFRP arrangement, a specimen(Type-A) with a single insertion of GFRP for each layer have shown the most favorable performance. Also, it was verified that densi- fied specimen hot pressed for an hour at the temperature of 150°C and with the oppression pressure 1.96 N/mm 2 have shown the improved performance of 1.57 times than the specimen without the densification.

Pillared-layer cluster organic frameworks constructed from nanoscale Ln10 and Cu16 clusters.

Two pillared-layer cluster organic frameworks, [Ln5(μ3-OH)4(μ-H2O)Cu8I8L11]·H2O (L = 4-pyridin-4-yl-benzoate; Ln = Dy(1), Eu(2)), have been made by employing lanthanide oxide and copper(I) halide as the source of lanthanide and transitional metal under hydrothermal condition. Compared to the pillared-layer frameworks constructed from heterometallic layers and organic pillars, these two compounds are derived from lanthanide cluster organic layers and copper(I) halide cluster motifs. Thus, there are two distinct types of inorganic metal connectors in the structure, one is hydroxo lanthanide [Ln10(μ3-OH)8](22+) (Ln10) cluster, and the other is copper(I) halide [Cu16I16] (Cu16) cluster. The rational assembly of these two inorganic connectors and organic linear linkers leads to the formation of the two complexes here. To the best of our knowledge, they appear to be the first 3D frameworks constructed from decanuclear hydroxo lanthanide clusters. From the topological point of view, these compounds represent an intriguing example of a binodal (8,14)-connected net considering the Ln10 and Cu16 connectors as the nodes, revealing that they are typical high dimensional frameworks with high connected net based on high nuclearity nodes. Furthermore, elemental analysis, IR, TGA, PXRD, and UV-vis properties are also studied.

The New Dynamic Interlaminar Device for the Treatment of Early and Late Lumbar Degenerative Problems

Introduction The ultimate Clinical goal of Dynamic Stabilization using motion preservation Devices is to relieve Pain and to improve the function of the spinal motion segment (SMS). Essentially it should preserve and restore physiologic motion, while maintaining the balance and stability of the SMS by controlling motion and unloading the disk and or the facet joint. Since the Degenerative cascade cannot be stopped, so the Key is: 1. Try to treat in the early stage with Dynamic stabilization or 2. Try to treat in the late stage with decompression and Dynamic stabilization. Materials and Methods Three years nonrandomized prospective follow-up study of dynamic stabilization using IntraSpine for the treatment of early and late degenerative cases. Follow-up: 2 weeks, 1, 2, 3, and 6 months after surgery. The dynamic stabilization using IntraSpine was performed by single surgeon. Assessment by dynamic X-ray, MRI, Ct-scan, and VAS before and after surgery. Results In 3 years, 67 cases of 23 males and 44 females, average age 56.9 (27 - 85 years old), were treated using IntraSpine. The variation levels of dynamic stabilization are related to the degenerative levels, from 1 to 5 levels, and from L1-2, until L5-S1. The skin incision is from 3 to 10 cm, the surgical time for 1 level with decompression is 45 to 4 hours for 4 to 5 levels. After 6 months, the result is excellent: VAS from average 8.3 to 1.2, dynamic X-ray stable, patient can do normal daily activity. Discussion The fundamental feature in the design of the new device IntraSpine is related to the anatomical reconstruction of the SMS and regarding the overturned anvil the anterior part (nose) of the device should be placed in between the laminae (Middle Column of Roy Camille) to control the load distribution and to achieve the “Sagital Balance” The interlaminar area is closer to the axis of instantaneous rotation of the SMS. The Complex Fascia Supraspinatus (CFS) is used as Natural Connector for this system, while the connector of pedicle system is metal connector. The IntraSpine is made of Medical Grade Silicone 65 shore coated by a pure PET sleeve Conclusion This report shows a good result of IntraSpine and match with the goals of Dynamic stabilization: 1. Stabilize the Segmental Instability, 2. Maintain the Sagittal Balance, and 3. Restore the physiologic movement of SMS. Disclosure of Interest None declared

New metal connectors developed to improve the shear strength of stone masonry walls

Stone masonry structures are widely used around the world, but they deteriorate easily, due to low shear strength capacity. Many techniques have been developed to increase the shear strength of stone masonry constructions. The aim of this experimental study was to investigate the performance of stone masonry walls strengthened by metal connectors as an alternative shear reinforcement technique. For this purpose, three new metal connector (clamp) types were developed. The shear strength of the walls was improved by applying these clamps to stone masonry walls. Ten stone masonry walls were structurally tested in diagonal compression. Various parameters regarding the in-plane behavior of strengthening stone masonry walls, including shear strength, failure modes, maximum drift, ductility, and shear modulus, were investigated. Experimentally obtained shear strengths were confirmed by empirical equations. The results of the study suggest that the new clamps developed for the study effectively increased the levels of shear strength and ductility of masonry constructions.

Cyclic behaviour of typical metal connectors for cross-laminated (CLT) structures

An extended experimental programme on typical cross-laminated (CLT) connections was performed at IVALSA Trees and Timber Institute. The paper discusses the results of monotonic and cyclic tests in shear and tension (pull-out) carried out on hold-downs and steel angle brackets used to anchor the wall panels to foundations or to connect wall panels to floor panels. Mechanical properties such as strength, stiffness, energy dissipation, impairment of strength and ductility were evaluated and are critically discussed in the paper. Significant ductility and energy dissipation was attained in most of the tests. Nevertheless, brittle failure modes were observed in some tests, indicating the need for introduction of capacity based design principles for CLT connections. The overstrength factors, which are needed for capacity based design, were also evaluated for the different types of connection tested. A comparison between the test results and the analytical formulas provided by current codes of practice and new proposals is also provided. The approach developed by Uibel and Blas gives slightly more accurate CLT metal strength predictions compared to the existing formulas in Eurocode 5. Both approaches lead to very conservative results. However, analytical models for the prediction of CLT metal connectors’ stiffness significantly overestimate the experimental values. Therefore, it is recommended that currently only experimental strength and stiffness values of hold-downs and angle brackets be used in seismic analyses. Some proposals to improve the mechanical performance of metal connectors in terms of strength and stiffness are also given based on this experimental and analytical study.

Experimental determination of load bearing capacity of connections realized by punched metal plate fastener

This paper demonstrates the results of experimental determination of load bearing capacity of structural timber member connections realized by WOLF and LKVC metal connector plates. Considering the complexity of the connections realized by these modern mechanical fasteners, this paper deals only with plate anchorage capacity (stress in the metal-wood contact). The aim of the conducted experimental study was to determine the metal connector plate anchorage capacity in accordance with the provisions of Eurocode 5 and also to analyze the ratio of the load bearing capacities of these two types of connectors in terms of their geometry. Experimental testing was conducted by loading of multiple samples up to the limit plate anchorage capacity. Discussion of the test results included the analysis of the connection deformation for different levels of load, as well as the mode of reaching the limit plate anchorage capacity. Review of the determined limit plate anchorage capacities, for the determined displacements of connection, was given in the conclusion, together with the comment on test results.

In vitro assessment of MRI issues at 3-Tesla for a breast tissue expander with a remote port

ObjectivesA patient with a breast tissue expander may require a diagnostic assessment using magnetic resonance imaging (MRI). To ensure patient safety, this type of implant must undergo in vitro MRI testing using proper techniques. Therefore, this investigation evaluated MRI issues (i.e., magnetic field interactions, heating, and artifacts) at 3-Tesla for a breast tissue expander with a remote port. MethodsA breast tissue expander with a remote port (Integra Breast Tissue Expander, Model 3612-06 with Standard Remote Port, PMT Corporation, Chanhassen, MN) underwent evaluation for magnetic field interactions (translational attraction and torque), MRI-related heating, and artifacts using standardized techniques. Heating was evaluated by placing the implant in a gelled-saline-filled phantom and MRI was performed using a transmit/receive RF body coil at an MR system reported, whole body averaged specific absorption rate of 2.9-W/kg. Artifacts were characterized using T1-weighted and GRE pulse sequences. ResultsMagnetic field interactions were not substantial and, thus, will not pose a hazard to a patient in a 3-Tesla or less MRI environment. The highest temperature rise was 1.7°C, which is physiologically inconsequential. Artifacts were large in relation to the remote port and metal connector of the implant but will only present problems if the MR imaging area of interest is where these components are located. ConclusionsA patient with this breast tissue expander with a remote port may safely undergo MRI at 3-Tesla or less under the conditions used for this investigation. These findings are the first reported at 3-Tesla for a tissue expander.

비정형 환경에 적용하기 위한 뱀 로봇 개발

This paper shows the development of a snake robot (KAEROT-snake V) which consists of 16 1-DOF actuator modules and head module. The modules are connected serially and the joint axis of each module is rotated by with respect to the previous joint so that the snake robot can move in the 3D space. A tail actuator module includes slip-ring and metal connector. KAEROT-snake IV developed in prior research could move in the 3D space and climb up in a narrow pipe. But its design was not appropriate to the unstructured tough environment and its speed was somewhat slow. A new actuator module is designed to enclose all parts of the module so that any wire is not exposed. The size and weight of the new module was slightly reduced. And the rotation speed and torque of the joint was increased by about twice when compared with pre-module. An embedded controller was developed so small that it can be mounted inside the module. The performance of the developed robot was demonstrated through various locomotion experiments.

Industry tubing characterization method for fixed speed applications

Efforts for structural tubing characterization are presented here for HVAC industry fixed speed applications. Structural tubing is a type of metal connector typically with hollow circular or rectangular cross-sections. Copper tubing is widely used in HVAC industry to transfer refrigerant between compressors and condensers. However, when the natural frequencies of tubing system are at the running speeds of the compressors; design life of the product is reduced. Therefore, tubing configuration structural change is needed to shift these problem frequencies. Traditionally, industry has been using finite element method and vibration tests to identify the critical geometric parameter for frequency shift. New efforts are been proposed here to present designer a sensitivity study tool to identify these critical parameters quickly, therefore, shorten the design cycle time.