Low Force Research Articles

Patient-specific gait pattern in individuals with patellofemoral instability reduces knee joint loads

AbstractPatellofemoral instability is influenced by morphological factors and associated with compensational alterations in gait pattern. Recent simulation studies investigated the impact of knee morphology on the stability and loading of the patellofemoral joint but neglected the patient-specific gait pattern. The aim of this study was to investigate the impact of patient-specific gait pattern on muscle forces and joint loading in individuals with patellofemoral instability. Musculoskeletal simulations with a model including a twelve degrees of freedom knee joint were performed based on three-dimensional motion capture data of 21 individuals with chronic patellofemoral instability and 17 healthy control participants. The patellofemoral instability group walked with a less flexed knee joint and reduced knee flexion and abduction moments compared to the control group, which required less quadriceps muscle forces. Lower quadriceps muscle forces resulted in a reduction of tibiofemoral and patellofemoral joint contact forces despite similar walking velocities between both groups. Furthermore, we observed decreased lateralizing patella forces in subjects with patella instability, which could potentially reduce the risk of patella dislocation. Our findings highlight the importance of accounting for the patient-specific gait pattern when analysing knee loads in individuals with patellofemoral instability.

Effect of Dietary Concentrate-to-Forage Ratios During the Cold Season on Slaughter Performance, Meat Quality, Rumen Fermentation and Gut Microbiota of Tibetan Sheep

This study aimed to investigate the effects of different dietary concentrate-to-forage ratios on slaughter performance, meat quality, rumen fermentation, rumen microbiota and fecal microbiota in Tibetan sheep. A total of sixty male Tibetan sheep were equally allocated into three dietary groups based on concentrate-to-forage ratios, i.e., 30:70 (C30), 50:50 (C50), and 70:30 (C70). Compared with the C30 group, sheep fed the C70 diet resulted in a higher (p < 0.05) slaughter live weight (SLW), hot carcass weight (HCW), dressing percentage (DP), eye muscle area, average daily gain (ADG), and ruminal total volatile fatty acids concentration and propionate molar proportion and lower (p < 0.05) shear force and cooking loss of meat, and ruminal acetate molar proportion and acetate:propionate ratio. Sheep in the C50 group exhibited a higher (p < 0.05) SLW, HCW, ADG, and ruminal propionate molar proportion and lower (p < 0.05) shear force and cooking loss of meat, and ruminal acetate molar proportion and acetate: propionate ratio compared with the C30 group. In rumen fluid, the relative abundance of Butyrivibrio was lower (p = 0.031) in the C30 group, and that of Ruminococcus was higher (p = 0.003) in the C70 group compared with the C50 group. In feces, genus Monoglobus and UCG_002 were the most abundant in the C30 group (p < 0.05), and the relative abundance of Prevotella was significantly higher in the C70 group than in other groups (p = 0.013). Correlation analysis revealed possible links between slaughter performance and meat quality and altered microbiota composition in the rumen and feces of Tibetan sheep. Overall, feeding a C70 diet resulted in superior carcass characteristics and meat quality in Tibetan sheep, thus laying a theoretical basis for the application of short-term remote feeding during the cold season.

Comparison of machining forces, power consumption, and specific cutting energy in tools with grooved cutting edges for sustainable manufacturing

ABSTRACT The ease at which a material is cut or formed to the required shape is defined as machinability. Higher machinability, superior productivity, and sustainability are the three key parameters used to evaluate machining performance. The tools designed to support these performance parameters are intended to consume less power, generate lower forces, produce surfaces with lesser roughness, and provide a higher tool life. Hence, the purpose of the investigation is to compare the efficiency of milling inserts with grooves (serrations) on the cutting edges (also called porcupine edges) in machining AISI 304 austenitic stainless steel and AISI 4140 low-alloy, medium-carbon steel materials. The metal cutting test results show that the milling inserts with grooved cutting edges consumed 8% to 17% less power and specific cutting energy, and exhibited 7% to 16% lower resultant force in AISI 304 steel. Similarly, 9% to 15% less power consumption, specific cutting energy, and 10% to 14% lower resultant force than the tools with straight cutting edges were also observed in AISI 4140 steel. The reduction in cutting power, specific cutting energy, and forces is credited to the decreased contact length between the tool edge and workpiece, providing lesser resistance in the inserts with grooved cutting edges.

Identifying latent subgroups of primary head injury: an explorative latent class analysis on neuropathologically examined medico-legal autopsy cases.

Traumatic brain injury (TBI) is a significant global health concern and frequently encountered in medico-legal autopsies. Previous studies suggest that certain TBI subtypes are more likely to co-occur than others. Therefore, we aimed to explore the potential of latent class analysis (LCA) to identify and characterize primary head injury combinations in neuropathologically examined medico-legal autopsy cases. The dataset comprised 78 cases from the Forensic Medicine Unit of the Finnish Institute for Health and Welfare over the period of 2016-2022. Data on background and circumstantial characteristics as well as primary and secondary head and brain injuries were collected from police documents, medical records, general autopsy reports and neuropathology reports. Latent class solutions with two to five classes were explored to identify clustering of primary head injuries among the sample. The dataset comprised 69.2% males and the median age was 49 years. In LCA, the solutions appeared reasonable, and each class appeared to represent a distinct TBI profile. The two-class solution was found to fit the present dataset best. Class 1 was characterized by older age, presence of an underlying CNS disease, and less diverse primary head injuries; these were interpreted as suggestive of lower traumatic forces. Class 2 was characterized by male sex and assaults as a prominent injury circumstance; subarachnoid and intracerebral/ventricular haemorrhages and contusions were classified exclusively into this class. In conclusion, this study identified two distinct subgroups of primary head injuries. Understanding typical injury combinations related to distinct circumstances could assist not only forensic pathologists but also clinicians treating TBI patients. However, the present latent class solution should not be interpreted as "ground truth", but instead further research is needed.

Throw distribution across the Dabbahu−Manda Hararo dike-induced fault array: Implications for rifting and faulting

Dike intrusion and formation of overlying dike-induced normal faults facilitate plate extension. The kinematics of these dike-induced normal faults provide an accessible record of subsurface diking. Here, we use high-resolution light detection and ranging (LiDAR) and interferometric synthetic aperture radar (InSAR) data to explore how strain was distributed across a preexisting dike-induced fault array during diking events in the Dabbahu−Manda Hararo magmatic segment (Afar, Ethiopia) in 2008 and 2010. By analyzing throw of the dike-induced normal faults, we show that only a small number of faults were reactivated during each diking event; the distribution of this reactivation likely reflects dike depth, opening, and inclination, as well as fault orientation. We also show fault throw favorably accrued toward fault centers, away from areas of soft- or hard-linkage. Our high-resolution data sets demonstrate the importance of reactivation to rifting, as it means extension can occur at lower extensional forces, and that fault slip (and seismic hazard) may not localize at sites of fault linkage.

The association between students' confidence and ability to modulate spinal manipulation force-time characteristics of specific target forces: a cross-sectional study.

Spinal manipulative therapy (SMT) is a guideline-recommended care for musculoskeletal pain taught in various undergraduate programs. Visual feedback through force-sensing tables can improve modulation of SMT force-time characteristics and, potentially, students' confidence, both factors important for clinical competence and patient outcomes. However, it is unclear if a link exists between students' confidence and ability in SMT force-time modulation. We aim to investigate this relationship and whether it was moderated by experience. This cross-sectional study recruited first- to third-year Canadian Memorial Chiropractic College students. Participants provided information about their confidence in performing SMT using different impulse forces of 200N, 400N, and 800N with a pre-established pre-load and a time-to-peak force < 150ms. SMT impulse forces of 200N, 400N, and 800N were targeted on a Human Analogue Mannequin positioned prone on a force-sensing table. We described the confidence levels and SMT force-time characteristics and assessed their association using linear mixed models. We re-ran the models interacting with SMT experience. The order of the three SMT impulse forces was randomly performed. Participants and outcome assessors were blinded to force-time characteristics recordings. One-hundred-and-forty-nine participants provided usable data. Participants were confident in delivering 200N and 400N impulse forces. However, confidence decreased for 800N forces. Accordingly, participants performed impulse forces close to the 200N and 400N but had difficulty accurately modulating to 800N forces. A positive association was found between confidence and the ability to modulate their force-time characteristics, especially keeping the same pre-load force, keeping the time to peak force < 150ms, and providing the 800N impulse force. This association was not moderated by experience. Students were more confident in their abilities to perform lower SMT forces but lacked confidence in their abilities to perform higher (800N) forces. This aligned with their skills, as many struggled to apply 800N force. However, students who had higher confidence levels generally performed better overall. There was substantial variability in SMT force-time characteristics, which may have implications for adverse events and patient satisfaction. Some of this variability could be attributed to students' confidence. Thus, further investigations are necessary in undergraduate settings to implement and optimize these findings. https://osf.io/6f7d5.

Mechano-responsive fluorescent gel based on tetraphenylethylene-crosslinked dynamic covalent network.

The rapid development of mechano-responsive fluorescence has been driven by its promising applications in the fields of sensors, information encryption, and anti-counterfeiting. However, designing mechanophores that can exhibit fluorescence changes under relatively low force remains challenging. In this study, a mechano-responsive fluorescent gel was developed using a tetraphenylethylene derivative as a cross-linker, producing a dynamic covalent network that exhibits increased fluorescence under tensile stress. Based on controlled experimental studies and molecular modeling calculations, the fluorescence enhancement by external forces was attributed to the restriction of intramolecular motion in tetraphenylethylene by macromolecular chain orientation. In time-dependent experiments, due to the exchange of dynamic covalent bonds, the stress relaxation and the decrease in fluorescence intensity of the gel at fixed strain occurred simultaneously, demonstrating the potential of this fluorescence as an indication of internal stress through aggregation-induced emission (AIE) type mechanophore.

A Study of Fit and Friction Force as a Function of the Printing Process for FFF 3D-Printed Piston–Cylinder Assembly

Current 3D printing processes for polymer material extrusion are limited in their accuracy in terms of dimension, form, and position. For precise results, post-processing is recommended, like with assembled parts such as pistons and cylinders wherein axial mobility is desired with low friction force and limited radial play. When no post-processing step of the printed parts is accomplished, the fit and the friction force behavior are strongly dependent on the process performances. This paper presents a study on parameters of significance and their effects on sliding and running fits as well as their friction forces for fused filament fabrication of such assemblies. A series of experiments were performed with multiple factors and levels, including the position or layout of printed objects, their layer thickness, the material used, the use of aligned or random seam, and the printer type. Piston–cylinder pairs were printed, measured, assembled, and tested using a tensile test frame. A mathematical model was developed to describe the oscillating friction force behavior observed. This study presents the feasibility and limitations of producing piston–cylinder assemblies with reduced play and friction when using appropriate conditions. It also provides recommendations to obtain and better control a desired running and sliding fit.

Near-Surface Reconfiguration of Biopolymer Blends by Mechanical Embossment: Creation of Friction-Reduced Foils

Biopolymer blends of polylactic acid (PLA) and polybutylene adipate-co-terephthalate (PBAT) are extruded into flexible monolayer films. These blends are excellent candidates for the realization of environmentally friendly packaging applications. A necessary pre-requisite for that are appropriate tribological properties under mechanical contact. Reasonable wear resistance allows good protection of packed goods, and low friction forces reduce difficulties in stacking. In this research, mechanical embossment under high loads at room temperature was used for the modification of polymer surfaces to exhibit a significant friction reduction under dry conditions. The results particularly show a systematic decrease in the coefficient of friction for biopolymer blends containing 30 wt% and 40 wt% PBAT. FTIR was used to analyze the change in surface composition after mechanical embossing. A sophisticated FTIR calibration method revealed that the blend with 30 wt% PBAT shows a modified distribution of PBAT and PLA at the surface due to mechanical embossment. This leads to a controlled and long-lasting modification of the surface properties without a substantial change in the chemical composition of the polymer in bulk. Without the use of additional coatings, biodegradable packaging foils with improved characteristics are accessible.

High‐Performance Alkaline Battery‐Supercapacitor Hybrid Based on Bimetallic Phosphide/Phosphate

AbstractTransition metal‐based materials explored for energy storage applications viz. batteries, supercapacitors and more recently battery‐supercapacitor hybrids (BSHs) abundantly involve Co‐based materials. However, the supply chain issues and low electronic conductivity force us to look for alternative options. In this regard, Co‐free binary metal phosphide/phosphate consisting of Ni and V metal (NiVP/Pi) microspheres as the positive electrode of BSH which shows a high specific capacity of 502 C g−1 (1004 F g−1) at 2 mV s−1 while retaining a high specific capacity of 214 C g−1 (428 F g−1) at 12 A g−1 is reported. The high electronic conductivity of binary metal phosphide in NiVP/Pi electrode and the rich electrochemical active sites due to Ni and V metal centres results in exciting performance. More interestingly, the hybrid device is successfully developed by employing NiVP/Pi as the positive electrode and carbon nanotubes (CNTs) as the negative electrode. The hybrid device (NiVP/Pi//CNT) is able to achieve a maximum energy density of 22.17 Wh kg−1 and a power density of 5 kW kg−1 with 91.7% capacitance retention after 7500 continuous galvanostatic charge–discharge cycles.

Lower limb joint loading during high-impact activities: implication for bone health.

Osteoporosis results in low-trauma fractures affecting millions globally, in particular elderly populations. Despite the inclusion of physical activity in fracture prevention strategies, the optimal bone-strengthening exercises remain uncertain, highlighting the need for a deeper understanding of lower limb joint loading dynamics across various exercise types and levels. This study examines lower limb joint loading during high-impact exercises across different intensities. A total of 40 healthy, active participants were recruited (mean ± SD: age of 40.3 ± 13.1yr; height 1.71 ± 0.08m; and mass 68.44 ± 11.67kg). Motion capture data and ground reaction forces of 6 different exercises: a self-selected level of walking, running, countermovement jump, squat jump, unilateral hopping, and bilateral hopping were collected for each participant. Joint reaction forces were estimated using lower body musculoskeletal models developed in OpenSim. Running and hopping increased joint forces compared to walking, notably at the hip (83% and 21%), knee (134% and 94%), and ankle (94% and 77%), while jump exercises reduced hip and ankle loading compared to walking (36% and 19%). Joint loading varied with exercise type and intensity, with running faster increasing forces on all joints, particularly at the hip. Sprinting increased forces at the hip but lowered knee and ankle forces. Higher jumps intensified forces on all joints, while faster hopping reduced forces. The wide variation of lower limb joint loading observed across the exercises tested in this study underscores the importance of implementing diverse exercise routines to optimize overall bone health and strengthen the musculoskeletal structure. Practitioners must therefore ensure that exercise programs include movements that are specifically suitable for their intended purpose.

Experimental Study on the Crushing Strength of Diamond Grains

This study investigates the crushing strength of single diamond grains of varying grades and particle sizes using the WDW-100 electronic universal testing machine. The research aims to understand the mechanical properties of diamond particles, which are critical for optimizing the performance of diamond tools in industrial grinding processes. High-grade diamond particles, characterized by their regular polyhedral shapes and minimal impurities, exhibit higher and more stable maximum load forces compared to medium- and low-grade particles. Medium-grade particles show a balance between strength and brittleness, while low-grade particles display significant variability in their structural integrity due to higher impurity levels and defects. The study also reveals that larger diamond particles tend to have lower average maximum load forces, attributed to increased crystal defects and pronounced grain boundary effects. These findings underscore the importance of considering both the grade and particle size of diamond grains in applications requiring high mechanical strength. The insights gained from this research are essential for improving the design and durability of diamond tools, ensuring their efficiency and longevity in industrial applications.

Simultaneous cutting and grinding of micropins using cylindrical microtools

Decreasing cutting force is always crucial in cutting processes. One method to achieve this is by minimizing tool wear, for which rotary cutting is a highly effective technique. The use of a cylindrical tool offers the additional benefit of easy tool fabrication, which is especially advantageous for a microtool capable of machining micropins. However, there have been no reported studies on rotary cutting using a cylindrical microtool. It should be noted that if a microtool is fabricated by electrical discharge machining, it is expected to engage in cylindrical grinding as well. This suggests that both rotary cutting and cylindrical grinding can be carried out simultaneously; however, there have also been no reported studies on simultaneous cutting and grinding. Therefore, the present study investigated whether this machining method can perform micropin machining, if it actually involves both cutting and grinding actions, and whether the combination of these actions enhances material removal capability. In turning and grinding experiments, where only one of the tool and workpiece was rotated, both actions were observed. Furthermore, it was confirmed that micropin machining can be performed by rotating both the tool and workpiece, resulting in a decrease in machining force to approximately one-quarter to one-half compared to that of turning. This indicates that simultaneous cutting and grinding was carried out, and the overlap of their actions enhanced material removal capability. In addition, the relationship between the machining conditions and machining force was investigated. At a small depth of cut, a tool with smaller surface roughness exhibited lower machining force than a tool with larger roughness, and the opposite was true at a large depth of cut. Finally, an ultrasmall-diameter micropin with a diameter less than 3 μm was successfully machined using conditions capable of reducing machining force.

Fatigue-induced alterations in force production, trajectory and performance in alpine skiing

ABSTRACT In giant slalom, the ability to apply a high amount of force in the radial direction is essential for performance. A race is characterized by repeated turns performed at high velocity, potentially inducing fatigue. Therefore, this study aimed to assess the effect of fatigue on performance, trajectory characteristics, and force production capacities onto the snow. Twelve skiers ran a 4-turn section with (FATIGUE) and without pre-induced fatigue (CONTROL). Knee extensor maximal voluntary contraction (MVC) was performed before the experiment and after both conditions. Section time, energy dissipation, path length, total force output, force application effectiveness, and EMG activity of the main lower-limb muscles were compared between conditions. Multiple linear regressions were used to understand whether interindividual variability in the kinematic, kinetic and EMG between conditions explains variability in performance changes with fatigue. MVC was lower after FATIGUE (−19.1 ± 6.4%, p < 0.001) but did not change after CONTROL. FATIGUE was associated with longer section times (+0.21 ± 0.11 s, p < 0.001), energy dissipation (−0.78 ± 1.05 J.s.kg.m−1, p = 0.026), path length (+1.1 ± 1.6 m, p = 0.033) and lower force application effectiveness (−0.1 ± 0.1, p = 0.017). This study experimentally demonstrates that fatigue in giant slalom results in lower force application effectiveness, inducing over-dissipation of mechanical energy and longer path length, leading to lower performance.

On the Inverse Correlation Between the Thermosphere Winter Helium Bulge and Solar Activity: Impact of Gravity Wave Drag From the Mesosphere

AbstractUnderstanding the temporal and spatial variations in the ideal inert tracer helium can provide insight into the dynamic evolution of the thermosphere. The magnitude of the thermospheric winter helium bulge was inversely correlated with the level of solar activity. However, this feature has been found to be not reproduced by the Thermosphere‐Ionosphere Electrodynamic General Circulation Model (TIEGCM), and the associated physical mechanisms remain unknown. Using the Thermosphere‐Ionosphere‐Mesosphere Electrodynamic General Circulation Model (TIME‐GCM), we found that mesospheric gravity wave drag (GWD) is a factor contributing to this inverse correlation. Specifically, the summer‐to‐winter circulation in thermosphere becomes the main cause of the helium bulge, as mesospheric GWD can play a role in strengthening this circulation. The GWD contributions to temperature change below the lower thermosphere do not depend prominently on solar activity. However, because the temperature impacts on the pressure gradient force are height‐integrated according to the background temperature of the neutral gas, the higher background temperature in the thermosphere at the solar maximum corresponds to a relatively weaker response in pressure gradient force in the thermosphere. Therefore, the response of the thermospheric circulation that might be expected to accompany increasing solar activity is suppressed due to the influence of mesospheric GWD, which results in a decrease in the magnitude of the winter helium bulge with increasing solar activity. Thus, our results demonstrated that lower atmosphere forcing can play a significant role in the response of thermospheric helium to solar activity.

Is biomechanical loading reduced in individuals with unilateral transtibial amputation during fast-paced walking when using different ankle/foot prostheses? A pragmatic randomized controlled trial.

Sound side loading is a risk factor for osteoarthritis development, which has been noted to reduce when using advanced prostheses during normal-paced walking in individuals with unilateral transtibial amputation (UTTA). However, descriptions of loading during fast-paced walking remain relatively unreported. Therefore, the aim of this study was to describe the biomechanical loading of individuals with UTTA while using different ankle/foot prostheses during fast-paced walking. A blinded, randomized control trial was conducted in a group of K3-K4 ambulators, who used 3 different prosthetic feet (1. a solid ankle cushioned heel foot prosthesis [SACH], 2. a standard energy storage and return foot prosthesis [ESAR], and 3. a novel ESAR foot prosthesis [N-ESAR]) in a 2-week randomized crossover design. The spatiotemporal and kinetic data of the participants' fast walking pace were collected. Data were analyzed using a mixed model and one-way analysis of variances (p < 0.05) and Cohen d. Twenty individuals with UTTA (age: 40 ± 16 years; height: 1.76 ± 0.09 m; and BMI: 24.72 ± 3.63 kg/m2) participated in this study. There were minimal changes in the spatiotemporal data between the different prosthetic feet. When the participants used the N-ESAR feet, they had a lower peak vertical ground reaction force (p = 0.02) and external knee adduction moment (p = 0.02) on the sound side, as well as a higher distal shank power on the prosthetic side (p < 0.01). Overall fast-paced walking resulted in higher sound side loading forces compared with normal-paced walking. However, use of the N-ESAR prosthesis reduced the biomechanical loading on the sound side in individuals with UTTA while walking at a fast pace compared with the ESAR and SACH prostheses. The percentage change in the biomechanical loading from normal- to fast-paced walking of the N-ESAR foot was also larger compared with the other prostheses, perhaps because of the individuals' ability to achieve a faster walking pace when using the N-ESAR prosthesis. Longitudinal intervention studies should be performed to further investigate the possible benefits of using advanced prostheses.

The Influence of Pigments on Ultrasonic Welding Behaviour of 3D Printed Components Using the Low Force Stereolithography Technology

The purpose of this paper is to study the strength characteristics of V4 resin components that are welded using ultrasonics. These components are created using the Low Force Stereolithography (LFS) technology, which reduces the printing forces for achieving the best possible finish. Welding components are 3D printed with a Form 3+ 3D printer, known for its high printing precision, employing a powerful laser and a spatial filter. Key characteristics of the ultrasonically welded components can be extracted, analysed, and summarized to provide guidance on the optimal resin selection.

Enhancing orthogonal finishing machining of Ti6Al4V with laser-ablated tool geometry modifications

Finishing machining of Ti6Al4V, known for its high strength and heat conduction resistance, demands optimisation to achieve high-quality end products. This study explores modifying the chip contact length on the rake face and altering the flank face with a cavity to minimise process forces and temperatures while maintaining cutting edge integrity. The research validates the manufacturability of ultra-short pulsed laser-ablated tool geometry modifications, indicating potential for industrial scale-up. Extensive experimental evaluations under dry conditions assess the impact of tool modifications at various feed rates for planing and turning. Significant reductions in process forces and temperatures were observed with rake face modifications, particularly at a cavity distance of approximately 34 µm. Ideal performance was noted for feed rates between 0.035 and 0.045 mm for planing and 0.040 to 0.045 mm/rev for turning. Smoothed Particle Hydrodynamics (SPH) simulations employing a Johnson-Cook material model were used to analyse chip formation and to predict the process forces. These simulations revealed a clear change in the chip formation and lower process forces and temperatures. The SPH results closely matched experimental outcomes, with a discrepancy of less than 7 % in cutting forces for both tool types, although feed forces were underestimated by about 50 %. The effect of the tool modification is reflected accurately at the respective feeds.

Effects of a soft back exoskeleton on lower lumbar spine loads during manual materials handling: a musculoskeletal modelling study

The aim of this study was to append a passive soft back exoskeleton to a validated musculoskeletal model and assess its effectiveness in reducing lumbar loads. Fifteen participants lifted a box, with and without wearing a CORFOR® exoskeleton. A full body OpenSim model was used to estimate lumbar joint moments and reaction forces, as well as low back muscles forces. Wearing the exoskeleton reduced the peak flexion moment, muscles forces, as well as peak compressive and shear forces. This musculoskeletal modelling study shows that wearing the exoskeleton may reduce lumbar spine loads and may contribute to prevent low back disorders.

Modeling of Multibody Lubrication Dynamics in Cylindrical Roller Bearings

As a typical multibody system, rolling bearing consists of several lubricated frictional pairs which transmit motions and forces among components. In this paper, a multibody lubrication dynamics (MLD) model of cylindrical roller bearings (CRBs) is developed by coupling the bearings dynamics sub-model and several lubrication sub-models of each frictional pairs in real-time. The lubrication sub-models are discretized by using finite difference and solved by numerical iteration methods of Gauss-Seidel with line relaxation and discrete convolution-fast Fourier transform (DC-FFT) technique. What’s more, a parallel algorithm is also designed to enhance the calculation efficiency. Its results are validated by the experimental results in literature, and further compared by the results from other dynamics models. It is revealed that the film formation changes not only friction but also geometrical constraints and pressure distribution, which may introduce additional load inside bearing and increase rolling friction under high-speed conditions. As the dynamic oil film stiffness and damper are took into account by MLD, the cage has a lower whirl frequency and forces. The curve-fitting formulas of EHL film thickness are overestimates the thickness value, and thus change the load distribution and friction between roller and raceway.