Twist Lock Research Articles

Dynamic investigation of a seven-tier container stack with different lashing arrangements subject to rolling and pitching excitation

ABSTRACT The current safety assessments of lashing systems and container stacks in various classification societies are based on static conditions, while dynamic behaviours are neglected. In this paper, the dynamic mechanical behaviour of a seven-tier 20-ft ISO freight container single stack and lashing devices under the combined rolling and pitching excitation is studied respectively. Through experiments and numerical simulations, five typical lashing arrangements are compared. The results show that a reasonable configuration of lashing stiffness, twist lock gap and lashing arrangement can decrease the dynamic response of the system. The external lashing arrangement is more suitable for the heavy stowage situation. The twist lock structure is more prone to failure in the horizontal direction than in the vertical direction, and a reasonable horizontal gap can effectively prevent the shear force from exceeding the allowable value. Finally, the benefits and drawbacks of each lashing arrangement for shipping companies are discussed.

Experimental and numerical investigation on dynamic response of a four-tier container stack and lashing system subject to rolling and pitching excitation

This research aims to investigate the dynamic responses of the lashing force, twist lock force, and container stack displacement under conditions close to real, providing a better understanding of the mechanism behind container damage and loss. Based on Froude scaling laws, a four-tier 20-ft ISO freight container stack and lashing assembly scaled model was built. The rolling and pitching driving excitation is provided by a shaking table. Input variables for the experimental and numerical simulation include driving excitation (amplitude and frequency), lashing methods (internal and external), twist lock gap (horizontal and vertical), contact and friction between adjacent corner castings. Output variables of the system contain the lashing force, twist lock's tensile and shear force as well as displacement of the container stack. The results of the present study are compared via numerical simulation, experiments, and theoretical calculations, suggesting that the external lashing is superior to the internal lashing when encountering high stack and heavy stowage. There are mutual coupling effects between the lashing methods, lashing force, twist lock force and twist lock gap. Moreover, decreasing the gap can minimize the stack displacement and lashing force, while it is not a viable solution to reduce the twist lock force.

Development and Suggestions on Container Twist Lock Handling in Automated Container Terminals

In this paper automated container terminals were introduced and characteristics of the automated container terminals were summarized. Besides, a common problem of twist lock handling technology in automated container terminal was proposed. different kinds of automatic twist lock handling technologies and equipment were collected and analyzed. Finally, suggestions on twist lock handling were given. With demands of automated container terminals, the twist lock handling technology will still rapidly develop in future.

Investigations on the dynamics of container stack and securing system under rolling motion using a scaled model test

ABSTRACT Currently, most existing studies and specifications for container stack and securing system are corresponding to static conditions. In this paper, we attempt to investigate the dynamic effects caused by hull movement on the stack and securing system. Based on Froude scaling laws, the four-tier 20-ft ISO container stack and lashing equipment scaled models are constructed. The physical and structural characteristics of the scaled models are determined by two dimensionless parameters: the gravity force/inertia force ratio, and the elastic force divided by inertia force. By inputting the sinusoidal excitation on the excitation device, a series of rolling tests were performed to study the effect of excitation, twist lock gap and payload on the dynamic response of the system. The experimental results are in a good agreement with the numerical simulation results. The results indicate that decreasing gap size and the proper cargo configuration can enhance the safety of the container stack.

Numerical analysis and experimental study on the scaled model of a container ship lashing bridge

Most existing studies and standards for containers and lashing equipment correspond to static conditions, which stresses current imperfections in the design specifications of the lashing bridge structure and gaps in experimental research. In this paper, an approach is proposed to study the mechanical behavior of the ultra-large containership lashing bridge structure. Based on Buckingham's Theorem and the Froude scaling laws, a scaled model test system with a container stack and twist lock is developed for a systematic experimental study of the lashing bridge. Additionally, the numerical analysis of the static, modal and dynamic response were carried out under the typical motion of the lashing bridge. Also, the coupling effect of the lashing bridge and hull structure is considered to design the system. The physical (size, mass, and moment of inertia) and structural characteristics (longitudinal, lateral, and torsional stiffness) of the proportional model are determined by two dimensionless numbers: Froude's number and Cauchy's number. The results suggest that the mechanical behavior of the ultra-large containership lashing bridge structure can be easily obtained from the reduced model. This can help to achieve the structural design and optimization, and the substructure coupling analysis of ultra-large lashing bridges.

컨테이너 샤시용 자동 컨테이너 고정 장치의 구조설계

Containers loaded on trailers are fastened using a locking device called a twist lock, which is manually operated. There have been instances where a container can fall off a tractor-trailer as a result of improper or inappropriate locking or unlocking. In this paper, we discuss the weaknesses of the locking mechanism of existing twist locks. This paper suggests a new design for an automatic locking mechanism that can be used to develop a better locking system and reduce the risk of container loss. Finite element analysis was also conducted to identify the structural stresses on each component; it was determined from the finite element analysis results, under each load condition, that the minimum safety factor was 1.06-2.41 for each part. Thus, it was discovered that the components had a structural intensity that did not exceed the yield strength.

The appearance of machining burr as a cracking failure on twistlock pin

The failure analysis of the twist lock pin made of alloy steel is presented. The pin was visually observed to have a cracking character at curvature area after 45,000 cycles. Some non-destructive inspections were previously done. However it failed to detect any crack defect. The twist lock pin sample was further macro and microscopic analysis. The analysis found that the surface discontinuities that were previously presumed as a cracking morphology was actually a machining burr and improper machining marks. There were some micro- and nano-sized pinholes dispersed over the metal matrix of the twistlock pin sample. The microstructure of the twistlock pin was tempered martensite structure.

Animal behaviour in a human world: A crowdsourcing study on horses that open door and gate mechanisms.

Anecdotal reports of horses opening fastened doors and gates are an intriguing way of exploring the possible scope of horses’ problem-solving capacities. The species’ natural environment has no analogues of the mechanisms involved. Scientific studies on the topic are missing, because the rate of occurrence is too low for exploration under controlled conditions. Therefore, we compiled from lay persons case reports of horses opening closed doors and gates. Additionally, we collected video documentations at the internet platform YouTube, taking care to select raw data footage of unedited, clearly described and clearly visible cases of animals with no distinct signs of training or reduced welfare. The data included individuals opening 513 doors or gates on hinges, 49 sliding doors, and 33 barred doors and gateways; mechanisms included 260 cases of horizontal and 155 vertical bars, 43 twist locks, 42 door handles, 34 electric fence handles, 40 carabiners, and 2 locks with keys. Opening was usually for escape, but also for access to food or stable-mates, or out of curiosity or playfulness. While 56 percent of the horses opened a single mechanism at one location, 44 percent opened several types of mechanism (median = 2, min. = 1, max. = 5) at different locations (median = 2, min. = 1, max. = 4). The more complex the mechanism was, the more movements were applied, varying from median 2 for door handles to 10 for carabiners. Mechanisms requiring head- or lip-twisting needed more movements, with significant variation between individuals. 74 horses reported in the questionnaire had options for observing the behaviour in stable mates, 183 did not, which indicates that the latter learned to open doors and gates either individually or from observing humans. Experience favours opening efficiency; subjects which opened several door types applied fewer movements per lock than horses which opened only one door type. We failed to identify a level of complexity of door-fastening mechanism that was beyond the learning capacity of the horse to open. Thus, all devices in frequent use, even carabiners and electric fence handles, are potentially vulnerable to opening by horses, something which needs to be considered in relation to keeping horses safely.

Use of a Wireless Video-EEG System to Monitor Epileptiform Discharges Following Lateral Fluid-Percussion Induced Traumatic Brain Injury.

The lateral fluid percussion injury (FPI) model is well established and has been used to study TBI and post-traumatic epilepsy (PTE). However, considerable variability has been reported for the specific parameters used in different studies that have employed this model, making it difficult to harmonize and interpret the results between laboratories. For example, variability has been reported regarding the size and location of the craniectomy, how the Luer lock hub is placed relative to the craniectomy, the atmospheric pressure applied to the dura and the duration of the pressure pulse. Each of these parameters can impact injury severity, which directly correlates with the incidence of PTE. This has been manifested as a wide range of mortality rates, righting reflex times and incidence of convulsive seizures reported. Here we provide a detailed protocol for the method we have used to help facilitate harmonization between studies. We used FPI in combination with a wireless EEG telemetry system to continuously monitor for electrographic changes and detect seizure activity. FPI is induced by creating a 5 mm craniectomy over the left hemisphere, between the Bregma and Lambda and adjacent to the lateral ridge. A Luer lock hub is secured onto the skull over the craniectomy. This hub is connected to the FPI device, and a 20-millisecond pressure pulse is delivered directly to the intact dura through pressure tubing connected to the hub via a twist lock connector. Following recovery, rats are re-anesthetized to remove the hub. Five 0.5 mm, stainless steel EEG electrode screws are placed in contact with the dura through the skull and serve as four recording electrodes and one reference electrode. The electrode wires are collected into a pedestal connector which is secured into place with bone cement. Continuous video/EEG recordings are collected for up to 4 weeks post TBI.

ANALISIS PERHITUNGAN DAN SIMULASI TEGANGAN TWIST LOCK RUBBER TIRED GANTRY CRANE (RTGC) KAPASITAS ANGKAT 35 TON DENGAN MENGGUNAKAN SOFTWARE AUTODESK INVENTOR 2014

Rubber Tyred Gantry Crane (RTGC) is a transport lifting equipment which serves to move the containers from head truck to the container terminal or vice versa and as a regulator of the composition of the container stacks. Twist lock is the most important components that are on Rubber Tired Gantry Crane (RTGC). This component is located on the four corners of the spreader. Twist lock function to lock the container at the time of appointment. And load the container will be distributed evenly. This study and simulation to calculate the voltage that occurs at the twist lock with variations in loading and adjusts the nature of the material used. The magnitude of the voltage is done with theoretical calculations and simulated using Autodesk Inventor 2014 software. Based on the research results, the loading of 20 tons, 30 tons and 40 tons with theoretical calculations obtained voltage value is 94705,33 kPa, 142057,98 kPa dan 189410,66 kPa. The simulation results obtained von mises stress value 91900 kPa, 137800 kPa dan 183800 kPa.

Biomechanical analysis of an interference screw and a novel twist lock screw design for bone graft fixation

BackgroundMalpositioning of an anterior cruciate ligament graft during reconstruction can occur during screw fixation. The purpose of this study is to compare the fixation biomechanics of a conventional interference screw with a novel Twist Lock Screw, a rectangular shaped locking screw that is designed to address limitations of graft positioning and tensioning. MethodsSynthetic bone (10, 15, 20lb per cubic foot) were used simulating soft, moderate, and dense cancellous bone. Screw push-out and graft push-out tests were performed using conventional and twist lock screws. Maximum load and torque of insertion were measured. FindingsMax load measured in screw push out with twist lock screw was 64%, 60%, 57% of that measured with conventional screw in soft, moderate and dense material, respectively. Twist lock max load was 78% and 82% of that with conventional screw in soft and moderate densities. In the highest bone density, max loads were comparable in the two systems. Torque of insertion with twist lock was significantly lower than with conventional interference screw. InterpretationBased on geometric consideration, the twist lock screw is expected to have 35% the holding power of a cylindrical screw. Yet, results indicate that holding power was greater than theoretical consideration, possibly due to lower friction and lower preloaded force. During graft push out in the densest material, comparable max loads were achieved with both systems, suggesting that fixation of higher density bone, which is observed in young athletes that require reconstruction, can be achieved with the twist lock screw.

Arthroscopic characteristics of meniscal injuries in osteoarthritic knees.

The aim of this study was to investigate the arthroscopic characteristics of meniscal injuries in osteoarthritic knees and explore their significance in the selection of surgical approach. Four original types of meniscal injuries were defined. The study included 87 cases; 12 Type 1, 26 Type 2, 35 Type 3 and 14 in Type 4 meniscal injuries. For Type 1 injuries, 5 cases underwent meniscal suture repair and 7 cases partial meniscal resection. Partial meniscal resection was performed in 22 cases and subtotal resection in 4 cases of Type 2 injury. For Type 3 injury, meniscal debridement was performed in 2, partial resection in 8, subtotal resection in 19 and total resection in 6 cases. For Type 4 injury, 3 cases underwent subtotal resection and 11 underwent total resection. Patients were evaluated with the Lysholm, visual analog scale, and Kellgren-Lawrence scale scores and cartilage lesions stages. Mean follow-up period was 26 (range: 8 to 51) months. Joint swelling or pain was present in 13 cases after fatigue. Twist lock symptom was observed in one Type 3 injury and one Type 4 injury. Joint flexion was limited to 20° in one Type 3 injury and two Type 4 injuries. Total knee joint replacement was performed in two Type 2 and two Type 4 injuries 2 to 3 years and 2 months after surgery. The classification of meniscal injuries in osteoarthritic knees was designed to guide arthroscopic surgery and improve the therapeutic efficacy of minimally invasive surgery for knee osteoarthritis.

Experimental and numerical analysis of container multiple stacks dynamics using a scaled model

This research aim to understand the mechanical behavior of container stacks under predefined driving excitation emulating real maritime conditions. The objects of study are scaled models (Froude scaling) of a 20 ft ISO freight container and its linking connectors, i.e., twist locks arranged in three adjacent seven-tier stacks. In the first stage of the study: a series of experiments were performed, using a shaking table, to build a database to calibrate a numerical model. The second stage of the study used a numerical model (F.E.A.) to understand the effect of structural changes and basic vibrational variables on the structural response of the stacks. The numerical analysis incorporates contact using the Kelvin–Voigt model. From the results it is possible to identify how each variable affects the structural response. Additionally, it is possible to calculate explicitly the loads on critical points of the structure. The evidence from this study suggests that the use of discrete damping elements, decreasing gap size and joining stacks, may help to minimize the structural response of the container stacks. The modeling of such a problem may provoke profound modifications on the current methods used to calculate loads on the stacks and securing (lashing) systems.

Experimental and numerical analysis of container stack dynamics using a scaled model test

This paper describes an approach to simulate a seven-tier stack consisting of scaled model of a 20 ft ISO freight container and its linking connectors, denominated twist locks, subjected to dynamical load induced by its base. The physical (dimensions, mass, and moments of inertia) and structural (longitudinal, transversal and torsional stiffness) characteristics of the scaled models were decided based on two dimensionless numbers: ratios between gravity force and inertia force, and elastic force divided by inertia force, through experimental and numerical analysis. A series of experiments with controlled parameters were performed using a shaking table test to understand the effects of each variable in the container stack dynamics and present enough data to validate the numerical model. The results of this study indicate that the numerical model built is a promising tool for further study. Moreover, the model is able to predict conditions close to real situations faced by container stacks while storage on a ship's deck.

On the vibrational characteristics of a two-tier scaled container stack

It is estimated that around 10,000 containers are lost during maritime transportation every year, representing an economic loss to the liner industry. Regulations and norms used to calculate values to secure them to the ship’s deck account for static loads only, neglecting more realistic conditions. This paper describes an approach to simulate a two-tier scaled model of a 20-ft ISO freight container and its linking connectors, denominated twist locks, subject to a dynamical load induced by its base. To analyze this problem two methods were employed: a shaking table test and finite-element analysis. Results of this study indicate that the numerical model built to simulate two-tier container stack dynamics is a promising tool for further studies. Moreover, the model is able to predict conditions close to real situations faced by container stacks while stored on deck.

English

Hydraulically-leveled platforms are required, to provide a leveled base for accurate leveling of high-rise masts and other vehicle-mounted communication devices. Design, development, and validation of one such platform on an 8x8, high mobility, wheeled vehicle is presented. The platform is a welded structure, designed to accommodate two ISO type shelters, and the shelters are secured to the platform at their four ISO corners using special twist locks. The leveling of the platform is enabled by actuation of four hydraulic cylinders bolted to the vehicle chassis. The concentrated type loading, resulting due to clearance maintained between the skids of shelters and the platform, and the loading pattern are the major design considerations. The other factors that have bearing on the design of platform include accommodation of variants of shelters, ease of operation of equipment mounted on the original chassis, and load distribution on axles, over-all height, ground clearance and departure angle of the integrated entity. Deflection and stress analysis of the platform structure using finite element analysis has been carried out for two types of shelter loadings. Limited track trials have been conducted at Vehicles Research & Development Establishment (VRDE) for assessment of structural integrity of the platform, and constructional and mobility aspects of platform-mounted-vehicle. Measurements of strain at critical locations, under-shelter loading, and while driving the vehicle at two different vehicle speeds on pave and cross-country tracks, have also been carried out for validation of design of platform. Details on problems faced during track trials, and the subsequent modifications carried out to the platform are also discussed.Defence Science Journal, 2010, 60(2), pp.169-177, DOI:http://dx.doi.org/10.14429/dsj.60.336

Paper #49 The twist-lock concept of tissue fixation without knots: observations along the Hong Kong skyline

Paper #49 The twist-lock concept of tissue fixation without knots: observations along the Hong Kong skyline

Is Your Pulmonary Artery Catheter Shedding?

President Critical-Care; Baxter Healthcare Corporation; Santa Ana, CaliforniaIn Reply:- We agree with the authors' comments that “… protective sheaths are a known source for damage to the (catheter) balloon …” and that “their potential for damaging the pulmonary artery catheter coating must be recognized.”Baxter salutes the authors' efforts to raise awareness of the potential for certain introducer systems with contamination shields to cause damage to a pulmonary artery catheter's thermal filament shield, balloon, or both.Product literature for the Arrow Twist Lock Cath-Gard Catheter Contamination Shield Model ST-09875 (80 cm) includes precautionary statements relating to possible balloon flotation catheters. The contamination shield has a firm, plastic feed tube running through the center of the shield, which supplies a path for the catheter to be passed through. Given the possibility that contact between the catheter and edges of the feed tube may disrupt the thermal filament sheath on the catheter, we agree with the authors' suggestion to visually inspect the integrity of the catheter after it has been passed through a contamination shield, before insertion into the introducer.We also wish to address the authors' comments that the thermal filament on a continuous cardiac output catheter is “an area less flexible and slightly thicker than the remaining part of the pulmonary artery catheter … .” With respect to Baxter's Swan-Ganz Continuous Cardiac Output/Oximetry/Venous Infusion Port (CCO/SvO2/VIP) Thermodilution Catheters, the diameter at the thermal filament area is equal to or slightly smaller than the rest of the catheter and shows comparable flexibility characteristics at all temperatures.Based on our experience and as indicated in the relevant portions of the product literature provided by Baxter and Arrow, certain steps should be taken to minimize the possibility of damage to pulmonary artery catheters that are inserted through contamination shields:1. Prepare the catheter for insertion per the manufacturer's instructions.2. Make sure both valves on the Arrow contamination shield at the proximal and distal hubs are in the widest open position.3. Wet the catheter balloon and thermal filament sheath with flush solution to facilitate passage through the valves of the contamination shield.4. Insert the catheter into the compressed shield and place the shield over the catheter so the distal flanged hub is beyond the 50-cm mark on the catheter.5. Inspect the catheter balloon and thermal filament sheath (if a continuous cardiac output catheter) for damage.6. If the catheter is not damaged, insert the catheter at least beyond the thermal filament into the introducer before moving the contamination shield, and then complete the catheter insertion following the manufacturer's instructions.7. Position, expand, attach, lock, and maintain the sheath as outlined in the manufacturer's instructions.Alan R. OlhoeftPresident Critical-Care; Baxter Healthcare Corporation; Santa Ana, California(Accepted for publication April 24, 1998.)

Transport of Irradiated Nuclear Fuel by Sea

Due to the application of the new IMDG regulations for the transport of radioactive material by sea, the conditions of transport have been analysed in detail by Transnucléaire in order to comply with these regulations. Following a commercial agreement between Transnucléaire and the French ship owner Company Morbihannaise de Navigation, to equip the ship named Bouguenais according to the INF Code Class 2, Transnucléaire has carried out considerable transport of radioactive materials by sea, in full compliance with the regulations, at a cost which is as close as possible to that of other industrial goods and without the need to dedicate the Bouguenais fully to this type of transport. Starting in July 1996 Transnucléaire has operated the sister ship of the Bouguenais, named Beaulieu, after fitting equipment to satisfy the INF (Class INF2) code requirement, in response to customers' demands and to offer more flexibility for ship availability. The two ships continue to be able to transport other industrial goods to amortise the fixed costs on a wider turnover basis. In addition, Transnucléaire has studied the possibility of reinforcing the structure of the two ships to meet the requirements of the INF3 Class and of the Japanese Regulations (KAISA 520). All transport packages are shipped to the final destination in approved ISO cargo containers that are well adapted to the stowing and handling of packages. The two ships are fully equipped with ISO twist lock systems. In line with the requirements of the French Competent Authorities, which are applicable in French ports or territorial waters, regarding nuclear material transport, Transnucléaire has studied the physical protection of the cargo. The need for deterrent measures to be implemented aboard ship has been foreseen, in order to afford some protection against the risk of misappropriation of Class II nuclear material while in transit. Transnucléaire is now able to track all its maritime cargoes carried by INF2 classified ships. In addition, Transnucléaire is studying salvage of the packagings in case a ship sinks. Accordingly, Transnucléaire is developing a safety response plan with IFREMER in order to be able to recover the packagings at any time and in the worst conditions, should the ship sink. All measures for transport, stowing and ship location and communications are ensured by Transnucléaire under proper conditions. All possible actions to preserve the environment and avoid any risk of damage are being studied by Transnucléaire. The goal is to ensure a good quality service and minimise any problems during the transport of radioactive material.

Efficient Storage System for Breath Hydrogen

Summary:Recommended materials for breath hydrogen collection (plastic syringes with twist lock closure) are only adequate for relatively brief periods because of gradual hydrogen loss and considerable variability between duplicate samples. To document the most favorable storage conditions for breath hydrogen, we compared hydrogen retention in plastic syringes using a conventional twist‐in‐lock closure versus a simple, inexpensive syringe closure, a Critocap. Hydrogen retention was studied at 25, 5, and – 20°C in two different syringe brands over 72 h of storage. An analysis of variance confirms the superiority of Critocaps over twist‐in‐lock closures (p < 0.001). Reliability was maximal when samples were placed in environments <5°C. When storage time was extended to 7 days, mean hydrogen retention was 86 ± 6% (± SD).