Torque Analysis Research Articles

Microscale bone interlocking enhances osseointegration strength on the rough surface of 3D-printed titanium implants: experimental and finite element analysis

BackgroundThe advent of 3D-printing technology, which is capable of on-demand fabrication, has ushered in a new era for fixed implant prosthodontics. Over the past decade, immediately loaded 3D-printed titanium implants have demonstrated predictable clinical outcomes in human jaws, highlighting their superior osseointegration strength, which is attributed to their increased surface roughness. However, the biomechanical mechanisms underlying this enhanced osseointegration strength remain elusive, thereby impeding the standardization and broader clinical application of 3D-printed titanium implants.MethodsExperimental 3D-printed titanium implants were fabricated via selective laser melting (SLM), and conventional sandblasted and acid-etched titanium implants (CNC-SLA) served as the control group. Implant surfaces were characterized with scanning electron microscopy, surface profilometry, energy-dispersive X-ray spectroscopy, and a contact angle meter. Implants (n = 10) were surgically inserted into the femoral condyle of New Zealand rabbits. At weeks 1, 2, and 8, micro-CT and undecalcified histological sections were used to assess histological osseointegration (n = 6), whereas removal torque analysis was performed to evaluate osseointegration strength (n = 4). At week 8, microscale finite element analysis of different bone-implant interfaces was conducted to predict the peri-implant bone strain under multidirectional implant loading.ResultsThe surface roughness of the SLM implants was significantly greater than that of the CNC-SLA implants. Histological osseointegration assessments revealed equal levels of SLM and CNC-SLA implants at weeks 1, 2, and 8. Notably, after week 2, bone interlocking phenomenon appeared on the SLM implants. The removal torque for the SLM implants at week 2 were significantly greater (P < 0.05) than that for the CNC-SLA implants at the same time point and was comparable to the CNC-SLA implants at week 8 (P = 0.775). The removal torque for the SLM implants at week 8 was further increased. Microscale finite element analysis revealed that the rough surface of the SLM implants dispersed harmful strains at the bone-implant interface into the surrounding bone, thereby mitigating the risk of damage to the bone-implant interface.ConclusionsThe rough surface of 3D-printed titanium implants fosters microscale bone interlocking and alleviates peri-implant bone strain concentration, which is a promising biomechanical basis for osseointegration strength.

Mapping method from human to robot arms with different kinematics

The accurate modeling from human arms to humanoid machine arms is the premise of humanoid robot's anthropomorphic compliant movement. In this paper, a mapping method simulating human upper limb motion mechanism is proposed to solve this problem. This method reconstructs the human arm model quickly and maps it to the dual-arm robot model. Firstly, the movement mechanism of human upper limb is analyzed and the upper limb model is established. According to the human double-arm kinematics theory, the calculation of arm motion rotation center and the analysis of force and torque are carried out. Then the mapping concept is used to start from the human morphological structure, establish a robot model similar to the arm structure and motion of the human hand, and generate the anthropomorphic configuration. At last, the data collected from the movement of human double arms are matched with the robot model, and the experiment verifies the feasibility of the proposed mapping method.

Methods for Assessing Orthodontic Mini Implant Stability

Assessing the stability of orthodontic mini implants (MI) is critical for ensuring successful treatment outcomes. This abstract reviews, various methods employed to measure MI stability in orthodontics. Invasive methods include histologic &amp; histomorphometry technique, cutting torque resistance analysis, removal torque analysis and insertion torque analysis. Non-invasive modalities such as surgeon’s perception, radiographic examination, finite element analysis, percussion test, pulsed oscillation waveform, Periotest and Resonance Frequency Analysis. Each method contributes uniquely to the assessment of MI stability, aiding orthodontists in making informed decisions regarding treatment planning and anchorage management. Understanding the strengths and limitations of these measurement methods enhances their clinical utility and ensures optimal treatment outcomes in orthodontic practice. Keywords: Orthodontic mini implants, Stability measurement, Orthodontics

Research on muck conditioning for EPB shield tunnelling in composite formation

Compared with simple formations, EPB (earth pressure balance) shield tunnelling in composite formations encounters severe problems with muck conditioning and require improved muck conditioning technology to fulfil expectations for continuous and efficient excavation. In the Nanchang Metro Line 4 Project, a water-rich sand-argillaceous siltstone composite formation is encountered. With a high moisture content and complex composite formation ratio, it is quite difficult to determine the optimum muck conditioning scheme, and thus, muck spewing accidents frequently occur during the tunnelling process. In this study, laboratory muck conditioning tests are conducted for five ratios of stratum, from a full section water-rich sand formation to a water-rich sand-argillaceous siltstone composite formation. The muck conditioner ratio for EPB shield tunnelling in such composite formations is dynamically optimized based on an analysis of propulsion speed, penetration rate, thrust force and torque of the shield machine in the field. The following muck conditioning scheme is obtained: (1) For the full-section water-rich sand layer, foam and bentonite slurry should have similar proportions, namely, the foam injection ratio is 10–15% and the bentonite slurry injection ratio is 10%. (2) As the argillaceous siltstone content increases from 10 to 90%, the foam injection rate gradually increases from 20 to 50%, and the bentonite slurry injection rate gradually decreases from 20% to 0. (3) If the argillaceous siltstone content is 10%, then CMC polymer with an injection ratio of 1% is required. Once the argillaceous siltstone content exceeds 70%, it is necessary to add mudstone dispersant solution (1:5) with a volume ratio of 2 to 3%. According to the analysis of the field tunnelling parameters, including penetration rate, total shield thrust and cutterhead torque, the optimization of the muck conditioning scheme proposed based on laboratory tests is proved effective and deserves further application.

Numerical and experimental analysis of guide vane pivot torque prediction in the reversible pump-turbine

In the last decades, Computational Fluid Dynamics (CFD) has played an important role in the numerical prediction of different characteristics of all types of hydraulic turbomachinery. Relative results of the characteristics curves for different hydraulic shapes can be predicted very accurately. On the contrary the prediction of the absolute values of various characteristics is still a challenge. In the paper, we would like to present the comparison between the results of the model testing and numerical analysis of the main reversible pump-turbine characteristics in pump and turbine mode: head, torque, efficiency and detailed analysis of prediction of the guide vane pivot torque for various operating regimes. Detailed model reversible pump-turbine measurements were done in hydraulic laboratory according to the international standard IEC 60193. Special attention was paid to the measurements of the guide vane torque. The research results include efficiency and QH curves derived from model tests and numerical analyses across various operating regimes. Dimensionless guide vane pivot torque values from both model tests and numerical analysis are compared and presented in diagram form. The comparison shows good agreement between the model test and CFD results. While steady-state CFD is generally accurate enough for turbine mode operation, unsteady calculations provide better results for pump mode operation. Numerous unsteady CFD analyses in turbine and pump mode operation demonstrate that CFD is equivalent or superior to model test in terms of speed, cost and accuracy. This research establishes that using CFD to predict guide vane pivot torque in hydraulic machines is now the most reasonable approach, eliminating the need for model tests.

Primary Stability of Dental Implants in Human Jawbones: Experiments & FE Analyses.

Primary stability (PS) is a key factor for promoting osseointegration and long-term success of dental implants particularly for immediate loading protocols. Beyond the current assessments of PS, an accurate pre-operative evaluation of PS would contribute to the improvement of surgical planning and treatment outcome. This study used biomechanical testing and homogenized finite element (hFE) analysis to objectively measure PS in the laboratory, and digitally estimate PS from prior μCT reconstructions. Thirty-five bone samples extracted from the jaws of two donors were examined. Twenty-two were finally evaluated for PS. After scanning of the samples with μCT, implants were inserted by two experienced surgeons, and various metrics such as μCT-based bone volume fraction (BV/TV), insertion torque (IT), and resonance frequency analysis (RFA) were assessed to determine PS. Mechanical testswere conducted to measure ultimate force (UFexp) as an objective indicator of PS while the hFE simulations were performed to estimate this same ultimate force (UFsim). Higher correlation was found between UFsim and UFexp (R2 = 0.85) than between BV/TV and UFexp (R2 = 0.61), IT and UFexp (R2 = 0.50), and RFA and UFexp (R2 = 0.38). All variables demonstrated a statistically significant linear correlation with UFexp (p < 0.01). UFsim turns out to be a more reliable and objective indicator of PS than IT and RFA. The hFE analysis requires prior μCT reconstructions and is currently limited by numerical convergence problems. Despite these limitations, pre-operative hFE analysis emerges as a promising tool with a higher accuracy for estimation of PS than state of care techniques.

Measurement of bone deformation and insertion torque during dental implant installation.

Insertion of dental implants causes bone deformation and induces residual bone compression stress, which can lead to implant failure if the bone loss threshold is exceeded. The current literature about bone stress is restricted to computer simulations and implant primary stability measurements after installation. This work measures the torque and deformation during implant insertion testing. The aim of this work was to analyze the influence surface treatment, thread profile, body shape and the presence of microthreads in the neck on the primary stability, bone deformation and residual stress during dental implants insertion. The insertion torque and resonance frequency analysis (RFA) are the main technique used to measure the primary stability of dental implants. Five models of dental implants with different surface treatments (machined and acid etching), thread profiles (triangular and trapezoidal) and body shapes (cylindrical and conical) were inserted in synthetic bone blocks (polyurethane) with a density of 30 PCF (0.48g/cm³) compatible with the D2 bone. The insertion torque was quantified by a digital torque driver. Strain gauge extensometry technique was used to measure bone deformation during implant insertion. The bone deformation and torque increase as the number of implants turns insertion increases. Dental implant with trapezoidal thread profile needs higher insertion torque than triangular threads. Implants with a conical shape require higher insertion torque than cylindrical ones. The bone stress induced by machined implant insertion exceeded the bone's mechanical resistance, causing cracks. Conical implants showed better performance than cylindrical ones. The implants with a trapezoidal thread and those with a conical body induce greater insertion torque. Comparing the mechanical behavior, it was found that the machined implants had the worst performance in terms of stress distribution in the synthetic bone, resulting in cracks in the specimen during insertion. Implants with trapezoidal threads and those with a conical body induce insertion torque and bone compression stresses that do not harm osseointegration. Excessive deformations in the peri-implant bone led to bone necrosis and implant failure. Thus, the surgeons must analyze the influence of surface treatment, thread profile, and body shape on the osseointegration process.

Comparative Analysis of Surface Roughness and Design Features of Titanium Dental Implants on Primary Stability and Osseointegration

ABSTRACT Objective: This study aimed to evaluate the impact of the surface roughness and design features of titanium dental implants on primary stability and osseointegration. Methods: Sixty titanium dental implants were categorized into three groups based on their surface roughness: smooth (Subgroup A1), moderately rough (Subgroup A2), and highly rough (Subgroup A3). Each roughness category was further divided into three design subgroups: cylindrical (B1), tapered (B2), and hybrid (B3). Primary stability was assessed using insertion torque and resonance frequency analysis (RFA). Osseointegration was evaluated through histological and histomorphometric analyses, measuring bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) at 4, 8, and 12 weeks post-implantation in rabbit models. Results: Highly rough-surface implants (Subgroup A3) demonstrated significantly higher insertion torque and ISQ values than smooth (Subgroup A1) and moderately rough (Subgroup A2) implants (P &lt; 0.001). Among the design features, tapered implants (Subgroup B2) exhibited the highest insertion torque and ISQ values (P &lt; 0.001). Histological and histomorphometric analyses revealed that highly rough-surface implants (Subgroup A3) and tapered implants (Subgroup B2) had the highest BIC and BAFO percentages at all time points (P &lt; 0.001). Conclusion: These findings indicate that both surface roughness and implant design significantly influence primary stability and osseointegration.

Design, Fabrication, and Performance Testing of PMMA Interference Screws Prepared by 3D Printing Methods

The Interference screws are one type of device that is often used in ACL reconstruction surgery. These devices are made of strong materials such as titanium or bioabsorbable materials. However, the use of PMMA (polymethyl methacrylate) as a material for the production of interference screws has not been widely explored. PMMA is commonly used in biomedical applications such as orthopedics and bone tissue engineering. Therefore, the aim of this study was to assess the structural integrity and performance characteristics of PMMA-based interference screws fabricated by utilizing three-dimensional (3D) printing techniques. The interference screw fabrication was carried out by adjusting the nozzle temperature, bed temperature, and print speed on the 3D printing machine to 240oC, 100oC, and 30 mm/s, respectively. The tests conducted in this study include torque, density, and fracture surface analysis. This study found that the density of the PMMA and commercial interference screws met the density requirements for cortical bone. However, the PMMA interference screw had a lower density than the commercial interference screw. The PMMA and commercial interference screws had densities (g/cm3) of 1.10 and 1.31, respectively. The mechanical properties of interference screws increase with increasing density. The PMMA interference screw achieved only 41% of the PFT (peak failure torque) exhibited by the commercial interference screw. In addition, the PMMA interference screw only meets the clamping criteria, while the commercial interference screw has met the good clamping criteria. The results of surface fracture analysis showed that the PMMA and commercial interference screws had ductile and brittle properties.

Torque (Performance) Analysis, Exhaust Gas Emissions and Exhaust Flow Modeling Variation of Catalytic Converter Filter Number

In a combustion engine, to generate torque, a combustion and compression process is required. Apart from obtaining mechanical energy, the combustion results also produce exhaust emissions, which can result in a polluted environment. This research aims to determine the influence of torque and exhaust gas emission modeling by using variations in the number of filters using simulation software. This research is descriptive and quantitative research with an experimental method. This research uses a Dyno test tool and a Gas Analyzer from this research to find out data from the exhaust that has been varied. The addition of a filter reduces the torque value by 1.7%. The presence of a filter on the catalytic converter has been proven to reduce levels of exhaust emissions that are harmful to the environment (CO, HC). Of the variations in the number of catalytic converters, filter number 2 is the best, producing 9.71 hp with CO emission levels of 1.7% and HC 553 PPM.

Finite element analysis and experimental verifications of low-speed rotor torque of magnetic-geared motor with permanent magnets only in stator

We propose a magnetic-geared motor with controllable step-out torque. The operational principle which controls the step-out torque using DC currents is described. The controllable step-out torque characteristics are computed using finite element method. In addition, the load characteristics under vector control are also computed using finite element method. Two inherent characteristics are observed in this analysis result. One is that this magnetic-geared motor can generate the torque more than the step-out torque. The other is that the phase angle difference between the rotors when both rotors step out is around 30 deg. In this paper, the mechanism of these inherent characteristics is investigated by finite element method, and these inherent characteristics are verified by carrying out measurements on a prototype.

Analysis of torque variation in bolt fastening on coated steel surfaces

Analysis of torque variation in bolt fastening on coated steel surfaces

Analysis of flow and energy dissipation in pump turbine with small guide vane opening

In this study, a detailed flow state analysis of a reversible pump turbine (RPT) under small guide vane opening conditions was conducted using both numerical simulation and experimental methods on three analysis planes at 0.5 span. The entropy production rate (EPR) in entropy production theory was utilized to visualize the location and magnitude of energy losses in the flow process. The focus was placed on the coherent vortex structures in the volute, stay vane, guide vane, and runner flow path. The results demonstrate that, throughout the runner’s cycle, the leading edge of the guide vane experiences low-pressure regions with uneven pressure distribution within the runner channel. Velocity streamlines reveal flow separation and vortex generation at the typical guide vane trailing edge, with a maximum velocity reaching 49.7. Analysis of radial force and torque on typical guide vanes and the runner indicates that radial force and torque on the guide vanes do not significantly change, with the radial force coefficient CF r−x varying between 0.254 and 1.3. Major energy losses are concentrated behind the trailing edge of the guide vane, primarily in the form of jet wake. Coherent vortex structures are observed in the volute, stay vane, guide vane, and runner flow path, with slight turbulent wake at the trailing edge of the stay vane, clear shedding vortex streets, and vortex build-up in the bladeless area between the guide vane and the runner.

A Novel Ungrounded Haptic Device for Generation and Orientation of Force and Torque Feedbacks.

To provide deeper immersion for the user in the virtual environments, both force and torque feedbacks are required rather than the mere use of visual and auditory ones. In this paper, we develop a novel propeller-based Ungrounded Handheld Haptic Device (UHHD) that delivers both force and torque feedbacks in one device to help the user experience a realistic sensation of immersion in a three-dimensional (3D) space. The proposed UHHD uses only a pair of propellers and a set of sliders to continuously generate the desired force and torque feedbacks up to 15N and 1N.m in magnitude in less than 370ms, respectively. The produced force and torque feedbacks are oriented in a desired direction using a gimbal mechanism where the propellers are mounted inside in such a way that a simple structure is obtained. These features facilitate the control of the proposed UHHD and enhance its practicality in various applications. To prove the capability of the system, we model it and elaborate on the force and torque analyses. Next, we develop a robust parallel force/position controller to tackle the structured and unstructured uncertainties. Finally, a measurement setup is manufactured to experimentally evaluate the performance of the UHHD and the controller. The implementation of the controller on the developed UHHD prototype shows that a satisfactory control performance is achievable in terms of offering the desired force and torque feedbacks.

Primary Stability of Dental Implants: A Comparative Evaluation of Five Implant Systems Using Insertion Torque and Resonance Frequency Analysis

Primary Stability of Dental Implants: A Comparative Evaluation of Five Implant Systems Using Insertion Torque and Resonance Frequency Analysis

Thermal-mechanical Coupling Model of Angular Contact Ball Bearing and the Influence of its Surface Roughness

Abstract A model that integrates thermal and mechanical aspects for an angular contact ball bearing (ACBB) has been introduced, considering its surface roughness. Subsequently, the analysis of friction torque, clearance, contact force, and temperature within the bearing is conducted under varying levels of surface roughness based on the established model. Additionally, the characteristics of thermal-mechanical coupling are examined under different conditions. The results indicate a significant interdependence between temperature and contact forces in the bearing system. It is observed that both friction torque and temperature increase with increasing surface roughness. This analysis provides valuable insights into the thermal-mechanical coupling characteristics of bearings.

A Novel Caterpillar-Inspired Vascular Interventional Robot Navigated by Magnetic Sinusoidal Mechanism

Magnetic soft continuum robots (MSCRs) hold significant potential in fulfilling the requirements of vascular interventional robots, enabling safe access to difficult-to-reach areas with enhanced active maneuverability, shape morphing capabilities, and stiffness variability. Their primary advantage lies in their tether-less actuation mechanism that can safely adapt to complex vessel structures. Existing commercial MSCRs primarily employ a magnetic-pull strategy, which suffers from insufficient driving force and a single actuation strategy, limiting their clinical applicability. Inspired by the inchworm crawling locomotion gait, we herein present a novel MSCR that integrates a magnetic sinusoidal actuation mechanism with adjustable frequency and kirigami structures. The developed MSCRs consist of two permanent magnets connected by a micro-spring, which is coated with a silicone membrane featuring a specific notch array. This design enables bio-inspired crawling with controllable velocity and active maneuverability. An analytical model of the magnetic torque and finite element analysis (FEA) simulations of the MSCRs has been constructed. Additionally, the prototype has been validated through two-dimensional in-vitro tracking experiments with actuation frequencies ranging from 1 to 10 Hz. Its stride efficiency has also been verified in a three-dimensional (3D) coronary artery phantom. Diametrically magnetized spherical chain tip enhances active steerability. Kirigami skin is coated over the novel guidewire and catheter, not only providing proximal anchorage for improved stride efficiency but also serving similar function as a cutting balloon. Under the actuation of an external magnetic field, the proposed MSCRs demonstrate the ability to traverse bifurcations and tortuous paths, indicating their potential for dexterous flexibility in pathological vessels.

Characterization and Dataset Compilation of Torque–Angle Curve Behavior for M2/M3 Screws

This research explores the torque–angle behavior of M2/M3 screws in automotive applications, focusing on ensuring component reliability and manufacturing precision within the recommended assembly specification limits. M2/M3 screws, often used in tight spaces, are susceptible to issues like stripped threads and inconsistent torque, which can compromise safety and performance. The study’s primary objective is to develop a comprehensive dataset of torque–angle measurements for these screws, facilitating the analysis of key parameters such as torque-to-seat, torque-to-fail, and process windows. By applying Gaussian curve fitting and Gaussian process regression, the research models and simulates torque behavior to understand torque dynamics in small fasteners and remarks on the potential of statistical methods in torque analysis, offering insights for improving manufacturing practices. As a result, it can be concluded that the proposed stochastics methodologies offer the benefit of fail-to-seat ratio improvement, allow inference, reduce the sample size needed in incoming test studies, and minimize the number of destructive test samples needed.

Full-arch prostheses supported by implants with different macrostructures: A multicenter randomized controlled trial.

This study evaluates the clinical performance of implants with hydrophilic surface and two different macrostructures: cylindrical with perforating triangular threads (CT) and cylindrical-tapered with the association of square and condensing and perforating triangular threads (TST). This was a multicenter split-mouth, simple-blinded, randomized, and controlled trial. Thirty patients with edentulous mandible received two CT and two TST implants. Primary stability was determined by insertion torque and resonance frequency analysis (RFA). Implants were loaded with full fixed-arch prostheses within 24 h after insertion. Clinical parameters (visible plaque index, marginal bleeding index; bleeding on probing; probing depth; and clinical attachment level) and the RFA were assessed at 2, 6, 12, and 24 months after implant loading. Marginal bone level changes were measured by comparison of standardized radiographs taken on the day of implant placement and 6, 12, and 24 months thereafter. Twenty-eight patients completed the 2-year follow-up. The survival rates were 99.16% for CT implants and 100% for TST implants. One CT implant was lost until the 2 months follow-up. No significant differences were found between the two implant types for marginal bone level changes (CT 0.34 [0.24; 0.55 mm]; 0.33 [0.18; 0.55 mm]; 0.41 [0.12; 0.7 mm] vs TST 0.36 [0.14; 0.74 mm]; 0.33 [0.23; 0.63 mm]; 0.30 [0.20; 0.64 mm] at 6, 12, and 24 months, respectively) and other clinical parameters. The macrostructure of the implants had no influence on survival rate, primary and secondary stability, marginal bone level changes, and peri-implant clinical parameters outcomes. Both implants can be predictably used for immediate loading of full-arch mandibular prostheses.

The Effect of Increasing Thread Depth on the Initial Stability of Dental Implants: An In Vitro Study

Background: The long-term success of dental implants largely depends on achieving primary stability, previously described as crucial to obtaining osseointegration and immediate loading protocol requirements. Implant thread depths seem to be one of the key factors influencing primary stability, particularly in low-density bone. Insertion torque (IT) and resonance frequency analysis (RFA) are considered the most reliable tests to assess primary stability. The aim of this work was to evaluate how different thread depths of commercially available dental implants affect primary stability in low-density D3 bone. Materials and Methods: An in vitro study was carried out between February 2024 and March 2024. Twenty-four dental implants were divided into four groups (six implants each) according to their thread depths (Group A: 4 mm, Group B: 4.5 mm, Group C: 5 mm, Group D: 5.5 mm) and were inserted in D3-type artificial bone blocks. The main outcome variables were the IT and the Implant Stability Quotient (ISQ) measured in four different areas of the implant (buccal, lingual, mesial, and distal) with an Osstel® ISQ reader. Descriptive and inferential analyses of the data were performed, and the significance value was set at 5%. Results: A total of 24 implants were analyzed. The highest IT values were obtained in Group D, with a mean of 54.03 Ncm (standard deviation (SD) = 8.99), while the lowest measurements were observed in Group A (mean = 25.12; SD: 2.96 N.cm). The mean ISQ values were consistently higher in Group D for each analyzed area, with a mean of 70.13 N.cm (SD = 1.12). Conclusions: Taking into consideration the limitations of this in vitro study, greater thread depths seem to increase the primary stability of dental implants placed in soft bone. Furthermore, a positive correlation was observed between all IT and ISQ values, regardless of the thread depth.