Rotary friction welding (RFW) is a green manufacturing technology with environmental pollution in the field of joining methods. In practice, the welding quality of the friction-welded parts was affected by the peak temperature in the weld joint during the RFW of dissimilar plastic rods. In industry, polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) are two commonly used plastics in consumer products. In this study, the COMSOL multiphysics software was employed to estimate the peak temperature in the weld joint during the RFW of PC and ABS rods. After RFW, the mechanical performance and microstructural evolution of friction-welded parts were investigated experimentally. The average Shore A surface hardness, flexural strength, and impact energy are directly proportional to the rotation speed of the RFW. The quality of RFW is excellent, since the welding strength in the weld joint is better than that of the ABS base materials. The fracture occurs in the ABS rods since their brittleness is higher than that of the PC rods. The average percentage error of predicting the peak temperature using COMSOL software using a mesh element count of 875,688 for five different rotation speeds is about 16.6%. The differential scanning calorimetry curve for the friction-welded parts welded at a rotation speed of 1350 rpm shows an endothermic peak between 400 to 440 °C and an exothermic peak between 600 to 700 °C, showing that the friction-welded parts have better mechanical properties.

/pdf/mechanical-performance-and-microstructural-evolution-of-2io7rqfl.pdf

Mechanical Performance and Microstructural Evolution of Rotary Friction Welding of Acrylonitrile Butadiene Styrene and Polycarbonate Rods

Introduction. Due to its simplicity, sliding mechanism is very often used in
 clinical practice for post-extraction space closure, however, the efficiency
 of this method may be reduced due to friction and changes in the properties
 of the materials used in this method. The most commonly used methods of
 sliding mechanics are nickel titanium (NiTi) closed coil spring and elastic
 chain. The aim of this study was to analyze force degradation in the
 application of nickel titanium closed coil springs and elastic chains during
 post-extraction space closure within treatment with fixed orthodontic
 appliances. Material and Methods. The total sample in this study consisted
 of 78 post-extraction spaces in patients who were indicated for extraction
 of first premolars and treatment with fixed orthodontic appliances. Nickel
 titanium closed coil springs and elastic chains were used to close the
 post-extraction spaces. Post-extraction spaces were monitored for 6 months
 with follow up examinations every 4 weeks. Measurements of initial force, at
 the beginning of mechanism activation and residual force in the observation
 period were performed during control examinations. Results. Results of this
 research showed that with both methods of sliding mechanism there was a
 significant decrease in the observation period. When using NiTi closed coil
 springs, the value of average initial force at control examination was
 between 189.00-210.25 g, while residual was in the range of 117.56-133.50 g
 that NiTi closed coil springs kept an average 61.57% of initial force. The
 average initial force on the control examinations for elastic chains was
 between 184.5-205.38 g, while residual force was in range of 100.39-113.00
 g, that elastic chains retained an average 53.41% of initial force.
 Conclusion. There was a significant force degradation between inspections,
 when sliding mechanics were applied. The loss of force between activation
 phases of NiTi closed coil springs was smaller compared to the forces
 produced by elastic chains.

http://www.doiserbia.nb.rs/ft.aspx?id=0039-17432203115U

Analysis of sliding mechanics force degradation during postextraction space closure

Multiforce nickel–titanium (NiTi) orthodontic archwires release progressively increasing forces in a front-to-back direction along their length. The properties of NiTi orthodontic archwires depend on the correlation and characteristics of their microstructural phases (austenite, martensite and the intermediate R-phase). From a clinical and manufacturing point of view, the determination of the austenite finish (Af) temperature is of the greatest importance, as in the austenitic phase, the alloy is most stable and exhibits the final workable form. The main purpose of using multiforce orthodontic archwires is to decrease the intensity of the applied forces to the teeth with a small root surface area, such as the lower central incisors, and also provide forces high enough to move the molars. With the optimally dosed forces of multiforce orthodontic archwires in the frontal, premolar and molar segments, the feeling of pain can be reduced. This will contribute to the greater cooperation of the patient, which is of utmost importance to achieve optimal results. The aim of this research was to determine the Af temperature at each segment of as-received and retrieved Bio-Active® and TriTanium® archwires with dimensions of 0.016 × 0.022 inches, investigated by the differential scanning calorimetry (DSC) method. A classical Kruskal–Wallis one-way ANOVA test and multi-variance comparison based on the ANOVA test statistic using the Bonferroni corrected Mann–Whitney test for multiple comparisons were used. The incisor, premolar and molar segments have different Af temperatures, and they decrease from the anterior to posterior so that the posterior segment has the lowest Af. Bio-Active® and TriTanium® with dimensions of 0.016 × 0.022 inches can be used as first leveling archwires by additional cooling and are not recommended for use on patients with mouth breathing.

/pdf/thermal-behavior-changes-of-as-received-and-retrieved-bio-fv6b3xmn.pdf

Thermal Behavior Changes of As-Received and Retrieved Bio-Active® (BA) and TriTanium® (TR) Multiforce Nickel–Titanium Orthodontic Archwires

Shape memory alloys (SMAs) are gaining popularity in the fields of automotive and aerospace engineering due to their unique thermomechanical properties. This paper proposes a numerical implementation of a comprehensive constitutive model for simulating the thermomechanical behavior of shape memory alloys, with temperature and strain as control variables to adjust the shape memory effect and super elasticity effect of the material. By implementing this model as a user subroutine in the FE code Abaqus/Standard, it becomes possible to account for variations in material properties in complex components made of shape memory alloys. To demonstrate the potential of the proposed model, a skid plate system design is presented. The system uses bistable actuators with shape memory alloy springs to trigger plate movement. The kinematics and dynamics of the system are simulated, and effective loads are generated by the shape memory alloy state change due to the real temperature distribution in the material, which depends on the springs’ geometrical parameters. Finally, the performance of the actuator in switching between different configurations and maintaining stability in a specific configuration is assessed. The study highlights the promising potential of shape memory alloys in engineering applications and demonstrates the ability to use them in complex systems with accurate simulations.

/pdf/shape-memory-alloys-applied-to-automotive-adaptive-2rz4gjv8.pdf

Shape Memory Alloys Applied to Automotive Adaptive Aerodynamics

Nickel-Titanium (NiTi) springs have been increasingly used in orthodontics; however, no optimum condition of heat treatment has been reported. Therefore, this research was conducted to determine the optimum heat-treatment temperature and duration for the fabrication of NiTi-closed coil springs by investigating their effects on thermo-mechanical properties. As-drawn straight NiTi wires of 0.2 mm diameter were used to fabricate closed coil springs of 0.9 mm lumen diameter. The springs were heat-treated at three different temperatures (400, 450, and 500 °C) with three different durations (20, 40, and 60 min). Electron Probe Micro-Analysis (EPMA) and Differential Scanning Calorimetry (DSC) were used to investigate element composition and thermo-mechanical properties, respectively. Custom-made NiTi closed coil springs composed of 49.41%-Ti and 50.57%-Ni by atomic weight, where their DSC curves of 500 °C presented the obvious endothermic and exothermic peaks, and the austenite finish temperature (Af) were approximately 25 °C. With increasing temperature, deactivation curves presented decreased plateau slopes generating higher superelastic ratios (SE ratios). At 500 °C, closed coil springs showed superelastic tendency with lower stress hysteresis. The thermo-mechanical properties were significantly influenced by heat-treatment temperature rather than duration. The optimum parameter appeared to be 500 °C for 40 min to produce appropriate force delivery levels, relatively low plateau slope, and lower hysteresis for orthodontic use.

/pdf/the-effects-of-temperature-and-time-of-heat-treatment-on-1a6qg44l.pdf

The Effects of Temperature and Time of Heat Treatment on Thermo-Mechanical Properties of Custom-Made NiTi Orthodontic Closed Coil Springs

To investigate the effects of different temperatures for heat treatment of custom-made NiTi closed coil springs. NiTi closed coil springs (50.8% Ni-49.2%Ti) were manually fabricated around a 0.9mm diameter mandrel and heat treated at temperatures of 400°C, 450°C, and 500°C for 20 minutes. The outer diameter of each specimen was measured to determine the effect of heat treatment temperature on spring geometry. Tensile tests were carried out to measure the force levels at 3, 6, 9, and 12 mm of spring extension. Non-parametric statistical analyses were done to assess and compare the effects of different temperatures of heat treatment on the custom-made orthodontic closed coil springs. Heat treatment at lower temperatures produced larger outer coil diameters than at higher temperatures. Raising the temperature of heat treatment produced significant increases in force levels by 13-18 g especially between 400°C and 500°C at spring extensions of 3, 6 and 9 mm. The highest superelastic ratio of 5.44 was found in the NiTi coil springs that were heat treatment at 500°C for 20 minutes which signifies superelastic tendencies. The mechanical properties of NiTi closed coil springs are influenced by the temperature of heat treatment. The NiTi closed coil springs that were heat treated at 500°C for 20 minutes produce appropriate force levels to display a superelastic tendency for orthodontic use.

Effect of Heat Treatment Temperature on the Mechanical Properties of Custom-Made NiTi Closed Coil Springs

We reported dental and craniofacial characteristics of an SJS patient with severe OSA. Not only does the syndrome cause skeletal abnormalities and myotonia, but it also affects the craniofacial development resulting in a severe constriction of maxillary arch and bimaxillary retrognathia which may increase a risk to develop pediatric OSA.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ccr3.3193

Thanate Assawakawintip

Papers

The Effects of Temperature and Time of Heat Treatment on Thermo-Mechanical Properties of Custom-Made NiTi Orthodontic Closed Coil Springs

Effect of Heat Treatment Temperature on the Mechanical Properties of Custom-Made NiTi Closed Coil Springs

Oral findings and craniofacial morphology in a patient with Schwartz-Jampel syndrome and severe obstructive sleep apnea: A case report.