Liner Motion Research Articles

A GEOMETRIC MODEL OF IMPINGEMENT DURING DISLOCATION-PRONE ACTIVITIES IN DUAL-MOBILITY AND STANDARD ACETABULAR CUPS

Dual Mobility (DM) Total Hip Replacements (THRs), are becoming widely used but function in-vivo is not fully understood.The aim of this study was to compare the incidence of impingement of a modular dual mobility with that of a standard cup.A geometrical model of one subject's bony anatomy \[1\] was developed, a THR was implanted with the cup at a range of inclination and anteversion positions (Corail® stem, Pinnacle® cup (DePuy Synthes)). Two DM variants and one STD acetabular cup were modelled. Joint motions were taken from kinematic data of activities of daily living associated with dislocation \[2\] and walking. The occurrence of impingement was assessed for each component combination, orientation and activity. Implant-implant impingement can occur between the femoral neck and the metal or PE liner (DM or STD constructs respectively) or neck-PE mobile liner (DM only).The results comprise a colour coded matrix which sums the number of impingement events for each cup position and activity and for each implant variant.Neck-PE mobile liner impingement, occurred for both DM sizes, for all activities, and most cup placement positions indicating that the PE mobile liner is likely to move at the start of all activities including walking.For all constructs no placement positions avoided neck-metal (DM) or neck-PE liner (STD) impingementevents in all activities. The least number of events occurred at higher inclination and anteversion component positions. In addition to implant-implant impingement, some instances of bone-bone and implant-bone impingement were also observed.Consistent with DM philosophy, neck-PE mobile liner impingement and liner motion occurred for all activities including walking. Neck-liner impingement frequency was comparable between both DM sizes (metal liner) and a standard cup (PE liner).

Quantifying Bone and Skin Movement in the Residual Limb-Socket Interface of Individuals With Transtibial Limb Loss Using Dynamic Stereo X-Ray: Protocol for a Lower Limb Loss Cadaver and Clinical Study.

Relative motion between the residual limb and socket in individuals with transtibial limb loss can lead to substantial consequences that limit mobility. Although assessments of the relative motion between the residual limb and socket have been performed, there remains a substantial gap in understanding the complex mechanics of the residual limb-socket interface during dynamic activities that limits the ability to improve socket design. However, dynamic stereo x-ray (DSX) is an advanced imaging technology that can quantify 3D bone movement and skin deformation inside a socket during dynamic activities. This study aims to develop analytical tools using DSX to quantify the dynamic, in vivo kinematics between the residual limb and socket and the mechanism of residual tissue deformation. A lower limb cadaver study will first be performed to optimize the placement of an array of radiopaque beads and markers on the socket, liner, and skin to simultaneously assess dynamic tibial movement and residual tissue and liner deformation. Five cadaver limbs will be used in an iterative process to develop an optimal marker setup. Stance phase gait will be simulated during each session to induce bone movement and skin and liner deformation. The number, shape, size, and placement of each marker will be evaluated after each session to refine the marker set. Once an optimal marker setup is identified, 21 participants with transtibial limb loss will be fitted with a socket capable of being suspended via both elevated vacuum and traditional suction. Participants will undergo a 4-week acclimation period and then be tested in the DSX system to track tibial, skin, and liner motion under both suspension techniques during 3 activities: treadmill walking at a self-selected speed, at a walking speed 10% faster, and during a step-down movement. The performance of the 2 suspension techniques will be evaluated by quantifying the 3D bone movement of the residual tibia with respect to the socket and quantifying liner and skin deformation at the socket-residuum interface. This study was funded in October 2021. Cadaver testing began in January 2023. Enrollment began in February 2024. Data collection is expected to conclude in December 2025. The initial dissemination of results is expected in November 2026. The successful completion of this study will help develop analytical methods for the accurate assessment of residual limb-socket motion. The results will significantly advance the understanding of the complex biomechanical interactions between the residual limb and the socket, which can aid in evidence-based clinical practice and socket prescription guidelines. This critical foundational information can aid in the development of future socket technology that has the potential to reduce secondary comorbidities that result from complications of poor prosthesis load transmission. DERR1-10.2196/57329.

POLYETHYLENE LINER MOTION IN DUAL MOBILITY HIP PROSTHESES: STATIC AND DYNAMIC RADIOSTEREOMETRY IN 16 CASES ONE YEAR AFTER OPERATION

Dual mobility hip arthroplasty utilizes a freely rotating polyethylene liner to protect against dislocation. As liner motion has not been confirmed in vivo, we investigated the liner kinematics in vivo using dynamic radiostereometry.16 patients with Anatomical Dual Mobility acetabular components were included. Markers were implanted in the liners using a drill guide. Static RSA recordings and patient reported outcome measures were obtained at post-op and 1-year follow-up. Dynamic RSA recordings were obtained at 1-year follow-up during a passive hip movement: abduction/external rotation, adduction/internal rotation (modified FABER-FADIR), to end-range and at 45° hip flexion. Liner- and neck movements were described as anteversion, inclination and rotation.Liner movement during modified FABER-FADIR was detected in 12 of 16 patients. Median (range) absolute liner movements were: anteversion 10° (5–20), inclination 6° (2–12), and rotation 11° (5–48) relative to the cup. Median absolute changes in the resulting liner/neck angle (small articulation) was 28° (12–46) and liner/cup angle (larger articulation) was 6° (4–21). Static RSA showed changes in median (range) liner anteversion from 7° (-12–23) postoperatively to 10° (-3–16) at 1-year follow-up and inclination from 42 (35–66) postoperatively to 59 (46–80) at 1-year follow-up. Liner/neck contact was associated with high initial liner anteversion (p=0.01).The polyethylene liner moves over time. One year after surgery the liner can move with or without liner/neck contact. The majority of movement is in the smaller articulation between head and liner.

Linear analytical model for magneto-Rayleigh–Taylor and sausage instabilities in a cylindrical liner

Recent experimental and numerical results demonstrates that the interfacial motion of a liner Z-pinch during the early stage of implosion may be controlled by the coupled effects of magneto-Rayleigh–Taylor (MRT), sausage, and kink instabilities. However, previous treatments of sausage instability have not considered the mechanical properties of the liner material. In this paper, we present an analytical model that allows us to study the effects of liner viscosity and elasticity on the coupling effects of MRT and sausage instabilities, and we further assume that the wavelengths are much smaller than the liner thickness by neglecting the feedthrough effect. The dispersion relations are analyzed. It is found that viscosity suppresses short-wavelength perturbations, and longer wavelengths are needed to achieve the fastest growing mode as the viscosity grows. Elasticity also strongly suppresses short-wavelength perturbations and eventually leads to the appearance of a cutoff wavenumber beyond which the interface always remains stable. In particular, the present approach provides the basis for the development of a more general theory that would also include magnetohydrodynamic instabilities and would allow a more accurate description of liner motion.

Novel Eddy Current Array Sensor Delivery Tool for Automated Nondestructive Examination of Spent Fuel Pool Liner

Abstract Inspection of a spent fuel pool (SFP) liner of a nuclear power plant is important to validate the integrity of this component to perform its intended function (e.g., confirm that there are not any defects in the pool liner). Eddy current array (ECA) testing offers a reliable and sensitive nondestructive examination (NDE) technique to inspect SFP liners but requires a delivery system to transport the ECA sensor to these hard-to-reach and harsh environment locations. This work presents an ECA sensor delivery tool design for use with inspection of an SFP. The design for a payload delivery tool proof-of-concept model is proposed that can transport an ECA sensor with positional feedback. The tool allows the sensor to traverse the wall of a nuclear SFP liner, with both horizontal and vertical motion capabilities to support positioning and inspection. The tool provides both manual and automatic operating modes with variable speeds. Computational-based simulations and analysis validate that the performance requirements for the ECA sensor delivery tool are satisfied to support inspection of an SFP liner upper region.

Comprehensive Analysis for Material Selection: Performance Evaluation for a Special Purpose Flexure

Considering a cryocooler for space applications, a special type of a flexure spring is fitted to assist the compressor motor and a displacer for liner motion thereby removing vibrations, frictional losses, and wear & tear. In the context of the critical application, the important physical parameter i.e., fatigue life of the flexure spring matters the most so that cryocooler does not fail during the operation. The present research study is an attempt to analyze the vital factors and attributes to determining the suitable material for accomplishing finite-fatigue life for the special flexure spring. A comprehensive analysis for material selection was conducted using the material options viz. a] AISI 304 Stainless Steel b] Beryllium Copper UNSC17200 c] Grade 5 Titanium (Ti-6Al-4V-3.7165-R56400) and d] AMPCOLOY® 944. Further, the materials stated were compared to their respective S-N curves. To decode the flexure spring’s performance evaluation, the parameters viz. load stresses, stiffness, displacement, geometrical configuration, etc. were analyzed using the Finite Element Analysis (FEA) package.

Polyethylene liner motion in dual-mobility hip prostheses: static and dynamic radiostereometry in 16 patients 1 year after operation.

Background and purposeDual-mobility hip arthroplasty utilizes a freely rotating polyethylene acetabular liner to protect against dislocation. As liner motion has not been confirmed in vivo, we undertook this using dynamic radiostereometry (RSA).Patients and methods6 patients with Anatomical Dual Mobility acetabular components were included. Markers were implanted in the liners using a drill guide. Static RSA recordings and patient-reported outcome measures were obtained postoperatively and at 1-year follow-up. Dynamic RSA recordings were obtained at 1-year follow-up during passive hip movement: abduction/external rotation, adduction/internal rotation (modified FABER–FADIR), to end-range and at 45° hip flexion. Liner and neck movements were described as anteversion, inclination, and rotation.ResultsLiner movement during modified FABER–FADIR was detected in 12 of 16 patients. Median (range) absolute liner movements were: anteversion 10° (5–20), inclination 6° (2–12), and rotation 11° (5–48) relative to the cup. Median absolute change in the resulting liner/neck angle (small articulation) was 28° (12–46) and in liner/cup angle (larger articulation) was 6° (4–21). Static RSA showed changes in median liner anteversion from 7° (–12 to 23) postoperatively to 10° (–3 to 16) at 1-year follow-up and inclination from 42° (35–66) postoperatively to 59° (46–80) at 1-year follow-up. Liner/neck contact was associated with high initial liner anteversion (p = 0.01).InterpretationThe polyethylene liner moves over time. 1 year after surgery the liner can move with or without liner/neck contact. The majority of movement is in the smaller articulation between head and liner.

Selection of structural materials for improved Liner motion gate valves based on friction correlation method

Selection of structural materials for improved Liner motion gate valves based on friction correlation method

Combined and hybrid marker models for radiostereometry assessment of polyethylene liner motion in dual mobility hip prosthesis: a proof-of-concept study

BackgroundInvestigation of polyethylene liner movement in total hip arthroplasty requires bead-marking for radiographic visibility of the liner. However, occlusion of markers poses a challenge for marker registration in radiographs.MethodsThe polyethylene of a dual mobility acetabular system was marked with twelve 1-mm tantalum markers (four groups of three markers) using a custom-made drill guide. Liner motion in a phantom and a patient was investigated with dynamic radiostereometry analysis (dRSA) at 1-year follow-up and static radiostereometry analysis (sRSA) postoperatively and at 1- and 2-year follow-up. A combined marker configuration (CMC) model was calculated from the registered positions of the liner markers and the femoral head in several images. Furthermore, the CMC model and the theoretic marker positions from computer-assisted models of the drill guide were combined in a hybrid model.ResultsThe CMC model included eleven markers in the phantom and nine markers in the patient, which was sufficient for dRSA. Liner movement in the phantom followed liner contact with the femoral neck, while liner movement in the patient was independent. The hybrid model was necessary to determine liner orientation in sRSA recordings, which clearly changed from postoperative to 1- and 2-year follow-up even though the patient was positioned similarly.ConclusionPolyethylene liner motion in dual mobility hip prosthesis can be assessed with CMC models in dRSA recordings. In sRSA, the liner position between follow-ups is unpredictable and analysis requires inclusion of all markers in the model, accomplished with a hybrid marker model.Trial registrationClinicalTrials.gov [NCT02301182], 25 October 2015.

Design and analysis of permanent magnet biased radial magnetic bearing with external rotor for vacuum tube

A permanent magnet biased radial magnetic bearing with external rotor for vacuum tube was introduced, and the configuration and operating principle were analyzed. The parameter design method based on the total magnetic flux was established to deduce the calculation formulas of the parameters of the permanent magnet radial magnetic bearing. The magnetic flux leakage coefficient and the magnetic resistance coefficient were considered, and the calculations were constrained to the degree of magnetic flux density unsaturation of the internal magnetic field of the soft magnetic material. Finite element software was used to execute simulation analysis and modeling of the permanent magnet biased radial magnetic bearing. The results show that the design method is reasonable and efficient, and the design magnetic bearing is compact and easy to control, which is more suitable for the liner motion with low power consumption.

On the hydrodynamic stability of an imploding rotating circular cylindrical liquid liner

The hydrodynamic stability of an imploding cylindrical liquid liner is analytically and numerically investigated. Such dynamic system can be used to compress gas trapped by the liner, as one may seek in a hydrogen fusion reactor. For such system it is vital for the liner to stay intact at least up to the turnaround point, which marks the point of maximum compression of the inner gas. New two-dimensional linear stability of Bell-type equation and Wentzel-Kramers-Brillouin (WKB) approximations are derived to account for the rotation of the liner. Excellent agreement is achieved between computational fluid dynamics (CFD) and 1D analysis for the trajectory of the unperturbed liner. Very good agreement is also achieved between the Bell type linear stability solution and the CFD until non-linear effects take hold near the turnaround point. The WKB approximation also agrees well but only at the early stage of the liner motion. Viscosity, surface tension and inner gas stability waves are found to have a small effect for a liner’s radial compression of up to ten. It is seen that the rotation has little effect on the perturbation amplitude during the accelerating stage of the liner, which is dominated by a slow oscillatory growth of a Bell-Plesset type at the studied conditions. However, at the decelerating stage towards the turnaround point, Rayleigh–Taylor rapid perturbation growth is suppressed at sufficiently large rotation rates. Hence, when coupled with non-linear saturation effects, the liner stays much intact until the turnaround point for radial compression ratios of up to ten. New simple linear stability limits are derived and are analysed.

Сравнение различных математических и численных моделей движения цилиндрического лайнера и их проверка

Сравнение различных математических и численных моделей движения цилиндрического лайнера и их проверка

Performance Assessment of a Near Room Temperature Magnetic Cooling System

Abstract In this study, performance of a near room temperature magnetic cooling system was investigated experimentally in terms of temperature span. The current setup has a permanent magnet pairs (0.7 Tesla), a magnetocaloric material (Gadolinium) and a heat transfer fluid (water, ethylene glycol and 10% ethanol-water mixing) furthermore solar energy was used as a power source of liner motion of the magnetic system. The obtained results showed that ethanol-water was the best heat transfer fluid and also that optimum magnetization-demagnetization period for the system was found 10 s.

Analysis of Dual Mobility Liner Rim Damage Using Retrieved Components and Cadaver Models

BackgroundThe objective of this study was to assess the retentive rim of retrieved dual mobility liners for visible evidence of deformation from femoral neck contact and to use cadaver models to determine if anterior soft tissue impingement could contribute to such deformation. MethodsFifteen surgically retrieved polyethylene liners were assessed for evidence of rim deformation. The average time in vivo was 31.4 months, and all patients were revised for reasons other than intraprosthetic dislocation. Liner interaction with the iliopsoas was studied visually and with fluoroscopy in cadaver specimens using a dual mobility system different than the retrieval study. For fluoroscopic visualization, a metal wire was sutured to the iliopsoas and wires were also embedded into grooves on the outer surface of the liner and the inner head. ResultsAll retrievals showed evidence of femoral neck contact. The cadaver experiments showed that liner motion was impeded by impingement with the iliopsoas tendon in low flexion angles. When observing the hip during maximum hyperextension, 0°, 15°, and 30° of flexion, there was noticeable tenting of the iliopsoas caused by impingement with the liner. ConclusionLiner rim deformation resulting from contact with the femoral neck likely begins during early in vivo function. The presence of deformation is indicative of a mechanism inhibiting mobility of the liner. The cadaver studies showed that liner motion could be impeded because of its impingement with the iliopsoas. Such soft tissue impingement may be one mechanism by which liner motion is routinely inhibited, which can result in load transfer from the neck to the rim.

A Review and Application of Linear Infinitely Variable Transmission in Automobile

In this paper, the linear Infinitely Variable Transmission in automobile engine use particular drive a Cam and number of follower rotary mounted a carrier plate to generate an auxiliary motion in equal number of planet gear the energy losses conventional transmission are unacceptable in scientific in manner. The variation of transmission including zero transmission ratios in cam and follower. The IVT has number of identical an unit ,each unit contain tree dimensional cam, cam follower, groove wheel, one way clutch(gear planet), though each unit rotational motion is converted in an oscillatory liner motion of variable amplitude and rectified to the rotation motion again. The motion maximum linear transmission ratio to the system depends on geometric design factors. This paper reviews the transmission system with a concept proposal for Infinitely Variable transmission.

The Study of LEFP Based on One Part of Semicircle Liner

In order to obtain the forming and the velocity of LEFP(Linear Explosively Formed Penetrators) based on one part of semicircle liner, the X-ray radiography and test velocity technology are used to obtain the forming and velocity of LEFP. In this paper, an analytical approach to describe the two-dimensional liner motion of LSCs is addressed firstly at a detonation-point. The relationship of LEFP flight distance can approximate a linear equation to estimate the distance of LEFP before contacting target. Experimental results showed that the shape of LEFP likes a scimitar according to gray image, and LEFP can close around linear explosive charge length axis direction.

Steady state equation of motion of a linear shaped charges liner

The sweeping detonation effect creates a unique turning angle of plates upon detonation. This effect was addressed by G. I. Taylor and opens a broad range of applications in many different engineering regimes. In case of linear shaped charges (LSCs), because of the unique geometrical shape, which are comprised of long, flat liners and multiple flat claddings, an approach to understand the performance of LSCs must be analyzed under the Taylor turning angle, motivating this research.In this paper, an analytical approach to describe the unique liner motion of LSCs upon detonation is addressed first. Subsequent modification of the original Birkhoff theory is addressed in order to build a steady state analytical equation of motion of LSCs liner based on the Taylor turning angle. The analytical model is then compared to the numerical simulation results created from Autodyn™ in terms of M/C ratio and apex angles in reasonable sized LSCs, and it exhibits favorable results in a limited range.

Motion of liner in various sections of magnetic compressor

The article discusses the simulation of acceleration and deceleration of a liner in a magnetic compressor. Two-dimensional approximations are considered, corresponding to the sections of the initial spatial area of transversal and longitudinal planes. The models are presented where the liner is considered as an elastic body, elastic-plastic body, and viscous liquid. The calculated results are presented and a comparative analysis of liner motion in various models is given.

Dynamic Analysis and Experiment Validation of Linear Motion Guide Having Rolling Elements for NC Machine Tool

To design a machine tool successfully, its essential parts should be analyzed and evaluated during the process of design. The liner motion guide is one of the most essential parts of the machine tool. So it is very important to analyze the dynamic-static characteristic of the machine tool consider linear motion guide and to study the effect on machinery function. The paper’s research is based on a NC machine tool produced by a certain plant of machine tools. Methods of simulating the linear rolling guide support are studied, and the configuration of the spring damper elements of the bearing supports are also studied, and the finite element analysis on the CKS6125 machine tool has been made to confirm its dynamic characteristics. Then the finite element analysis models are validated by some experiments.

Sub-Nanometer Positioning Combining New Linear Motor with Linear Motion Ball Guide Ways

A new type of linear motor described in this paper has some advantages compared with the usual types of motors. The attractive magnetic force between the stator (permanent magnets) and mover (armature) is diminished almost to zero. The efficiency is better because the magnetic flux leakage is very small, the size of motor is smaller and detent (force ripple) is smaller than the general motors. Therefore, we think that this motor is greatly suitable for ultra-precision positioning as an actuator. An ultra-precision positioning device using this motor and liner motion ball guide ways is newly developed. Moreover, the positioning performance is evaluated by a positioning resolution, deviational and dispersion errors. As the results of repeated step response tests, the positioning resolution is 0.3 nm, the deviational error is -0.001nm and the dispersion error (3σ) is 0.29 nm. Consequently, the positioning device achieves sub-nanometer positioning. In addition, very large rigidity can be achieved.