coil spring
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2022 ◽  
pp. 107754632110514
Author(s):  
Sivakumar Solaiachari ◽  
Jayakumar Lakshmipathy

In this study, a new type of vibration isolator based on fluidic actuators and a composite slab was tested experimentally with an unbalanced disturbance. Quasi-zero stiffness vibration isolation techniques are advanced and provide effective isolation performance for non-nominal loads. The isolation performance of the proposed isolator was compared to that of a nonlinear vibration isolator equipped with fluidic actuators and a mechanical coil spring (NLVIFA). The NLVIFA system is better suited to non-nominal loads; however, the mechanical spring axial deflection leads to limited amplitude reduction in the system. To address this issue, a cross buckled slab was developed to replace a mechanical coil spring for absorbing vertical deflection by transverse bending, which is made of a specially developed composite material of Basalt fiber reinforced with epoxy resin and enhanced with graphene nano pellets. This current study was concerned with the theoretical analysis and experimental investigations of the proposed nonlinear vibration isolator with fluidic actuators and composite material (NLVIFA-CM), which performs under quasi-zero stiffness characteristics. Because of its reduced axial deflection, the theoretical and experimental results show that the NLVIFA-CM system outperforms the NLVIFA system and other linear type vibration isolators in terms of isolation performance. Furthermore, the proposed vibration isolator makes a significant contribution to low-frequency vibration.


2021 ◽  
Vol 33 (2) ◽  
pp. 90-93
Author(s):  
Md Kamrul Hasan ◽  
Gazi Shamim Hassan ◽  
Samira Rahman ◽  
Md Sher Ali ◽  
Md Azizur Rahman ◽  
...  

Introduction: In Majority of patients seeking orthodontic treatment, teeth must be extracted in order to obtain proper esthetics, occlusion, and stability as well as extraction of teeth is often a need to close residual space, after the initial decrowding and aligning. Pre adjusted fixed orthodontic appliances commonly utilize sliding mechanics for space closure with different types of force delivery systems. A variety of materials have been used as force delivery systems to close spaces between teeth as in the case of canine retraction after the extraction of premolars. Among all sliding or frictionless methods of canine retraction, super-elastic nickel titanium coil spring has a particular property in producing light continuous force at a long range of action, compared with previously available materials. Nickel-titanium closed coil spring, with a continuous action, might have some advantages in fixed appliance space closure mechanics. Materials and Methods: Over the period of one year from May 2015 to April 2016, this clinical trial was carried out and A total number of 20 patients (40 quadrants), who required canine retraction into first premolar extraction sites as part of their orthodontic treatment in the Department of Orthodontics of BSMMU selected as study population. The quadrants were affixed by nickel titanium closed coil springs (medium force, Ni-Ti extension spring, Ormco) with 200gm force measured by Correx Tension Gauge. Space closure was measured by means of direct measurement from the mesial surface of mesial wing of the 2nd premolar bracket and the distal surface of distal wing of the canine bracket with digital Vernier Calipers. Results: Mean space closer rate in mandibular canine retraction was 1.07 ± 0.12 mm/month by nickel-titanium (Ni-Ti) closed coil spring method with p value<0.001. Conclusion: This study revealed that space closer rate in mandibular canine retraction by nickel-titanium (Ni-Ti) closed coil spring is 1.07 ± 0.12 mm/month. Medicine Today 2021 Vol.33(2): 90-93


Author(s):  
V. M. Zyablikov ◽  
A. A. Shirshov

The design of the coupling is considered in detail, its possibilities for connecting misaligned shafts are indicated. The interaction of the spring turns with the teeth of the half-couplings is considered in detail. A scheme of deformation (exaggerated) of the coils during the transmission of torque is proposed, according to which a calculation model is selected to determine the torsional rigidity of the coupling and the strength of the coils. It is shown that during the operation of the coupling, the coils of the spring not only bend, but also twist, increasing the stiffness, while their strength is estimated by an equivalent voltage. Misalignment of the connected shafts, as well as an increase in the gap between the coupling halves, leads to a decrease in torsional rigidity and an increase in stresses in the spring turns.


Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1424
Author(s):  
Daehwan Cho ◽  
Joonhong Park ◽  
Jaeil Kim

Studies have been actively conducted on systems that prevent the breakage of water pipes from freezing in winter. Shape memory alloy (SMA) coil springs have been used as the key components of actuators that can operate automatically by detecting the real-time outside temperature changes, but research on its use as an actuator that can operate at sub-zero temperatures is insufficient. This study proposes the anti-freezing system using Ni-44.08Ti-1.46Co (wt.%) SMA coil springs that operate near sub-zero temperatures to prevent the freezing accident of water pipes. After fabricating the SMA coil springs, the test for performance evaluation of the springs applied static load conditions was conducted on the specific outside temperature. To examine the operation of anti-freezing systems applied the SMA coil spring as an actuator, the water discharge test (WDT) was also conducted along with the computational fluid simulation. The results of water discharge measurement obtained by WDT, simulations, and theoretical equations applied to the fluid resupply system constructed were compared with each other to verify the reliability. Consequently, it was confirmed that water discharge can be automatically controlled in real time according to temperature changes of SMA coil springs in the anti-freezing system.


2021 ◽  
Author(s):  
Felix Simeon Egner ◽  
Yonggang Wang ◽  
Thijs Willems ◽  
Matteo Kirchner ◽  
Bert Pluymers ◽  
...  

Author(s):  
Asma Fatima ◽  
Prasad Konda ◽  
Asiya Fatima ◽  
Hidayathulla Shaikh ◽  
Butool Zohra ◽  
...  

Background: The ability to close space efficiently in Orthodontics is of major clinical importance. Elastomeric power chain, coil spring, and tiebacks are commonly used in Orthodontics to achieve tooth movement during the closure of spaces. Many mouth rinses which are used by the patients to achieve good oral hygiene affect the properties of the material used during treatment resulting in force decay if they contain alcohol. Aim: To know the effect of mouth rinses containing different alcohol Concentrations on the force decay of retraction materials. Materials and Methods: A study was carried out to test the effect of alcohol exposure found in mouth rinses on orthodontic NiTi closing coils, elastomeric chains, and tie-back. A total of 135 specimens were divided into one control group and two test groups submerged in artificial saliva at 37⁰ C. Two test groups each of them exposed to different alcohol-containing mouthwashes (Listerine and Povidone-iodine) for 60 seconds twice a day and the control group were exposed only to deionized (DI) water for 28 days. Force measurements were taken at six-time points (initial, 7 days, 14 days, 21 days, and 28 days) using a digital force gauge. Results: The comparison between the tensile strength was made by digital force gauge and the p-value (≤ 0.05) for tensile strength was derived by ANOVA test, multiple comparisons, and Tukey’s correction. Significant force decay was seen in test groups when compared to the control group. Conclusion: Force degradation of retraction products used during orthodontic treatment was effected by mouth rinses containing alcohol.


2021 ◽  
Author(s):  
Harshkumar Patel ◽  
Hong Zhou

Abstract Springs are mechanical devices that are employed to resist forces, store energy, absorb shocks, mitigate vibrations, or maintain parts contacting each other. Spring wires are commonly coiled in the forms of helixes for either extension or compression. Helical springs usually have cylindrical shapes that have constant coil diameter, constant pitch and constant spring rate. Unlike conventional cylindrical coil springs, the coil diameter of conically coiled springs is variable. They have conical or tapered shapes that have a large coil diameter at the base and a small coil diameter at the top. The variable coil diameter enables conical coil springs generate desired load deflection relationships, have high lateral stability and low buckling liability. In addition, conical compression springs can have significantly larger compression or shorter compressed height than conventional helical compression springs. The compressed height of a conical compression spring can reach its limit that is the diameter of the spring wire if it is properly synthesized. The height of an undeformed conical coil spring can have its height of its spring wire if the spring pitch is chosen to be zero. The variable coil diameter of conical coil springs provides them with unique feature, but also raises their synthesis difficulties. Synthesizing conical coil springs that require large spring compression or small deformed spring height or constant spring rate is challenging. This research is motivated by surmounting the current challenges facing conical coil springs. In this research, independent parameters are introduced to control the diameter and pitch of a conical coil spring. Different conical coil springs are modeled. Their performances are simulated using the created models. The deflection-force relationships of conical coil springs are analyzed. The results from this research provide useful guidelines for developing conical coil springs.


Author(s):  
Felipe Bergh ◽  
Gilmar Cordeiro Silva ◽  
Caio Silva ◽  
Pedro Paiva
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