scholarly journals Quantitative assessment of the level of instability of a single-plane balance platform

2021 ◽  
pp. 1-17
Author(s):  
Vaidotas Gudziunas ◽  
Aurelijus Domeika ◽  
Linas Puodžiukynas ◽  
Renata Gustiene
Keyword(s):  
Quantitative Assessment ◽  
Mechanical Characteristics ◽  
Balance Training ◽  
Vibration Damping ◽  
Damping Factor ◽  
Single Plane ◽  
Main Disadvantage

BACKGROUND: Balance training on unstable surfaces is widely used in medicine and sports. The main disadvantage of balance platforms is weakly definable assessment of the level of instability (IL) they create. OBJECTIVE: To evaluate the mechanical characteristics of a suspended single-plane instability balance platform which determines quantitative instability characteristics. METHODS: Three criteria influencing the IL were evaluated: 1. The displacement of the platform board by changing the position of the object on the board; 2. Amount of force required for board displacement; 3. The vibration damping of the platform. RESULTS: 1. 1IL the displacement of the object on the board affected 0.66 cm. the displacement of the board relative to the platform frame; 2IL – 0.79 cm; 3IL – 0.91 cm.; 2. A force of 2.64 is required for a board displacement of 1IL compared to 2IL and 5.76 times that of 3IL. 3. Damping factor 1IL – 0.015, 2IL – 0.006, 3IL – 0.003. CONCLUSIONS: 1. The longer the suspension, the change in the position of the object on the board affects the greater movement of the board relative to the platform. 2. Different IL can be compared with each other depending on how different the force required to cause the board to move. 3. The platform dampens vibrations weakly, but the damping between 1 and 3 IL differs about 5 times.

scholarly journals Self-Reinforced Nylon 6 Composite for Smart Vibration Damping

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1235
Author(s):  
Bidita Salahuddin ◽  
Rahim Mutlu ◽  
Tajwar A. Baigh ◽  
Mohammed N. Alghamdi ◽  
Shazed Aziz
Keyword(s):  
Matrix Material ◽  
Nylon 6 ◽  
Vibration Damping ◽  
Vibration Energy ◽  
Damping Factor ◽  
Passive Vibration Control ◽  
Reinforced Composite ◽  
Coiled Structure ◽  
The Matrix ◽  
3D Printed

Passive vibration control using polymer composites has been extensively investigated by the engineering community. In this paper, a new kind of vibration dampening polymer composite was developed where oriented nylon 6 fibres were used as the reinforcement, and 3D printed unoriented nylon 6 was used as the matrix material. The shape of the reinforcing fibres was modified to a coiled structure which transformed the fibres into a smart thermoresponsive actuator. This novel self-reinforced composite was of high mechanical robustness and its efficacy was demonstrated as an active dampening system for oscillatory vibration of a heated vibrating system. The blocking force generated within the reinforcing coiled actuator was responsible for dissipating vibration energy and increase the magnitude of the damping factor compared to samples made of non-reinforced nylon 6. Further study shows that the appropriate annealing of coiled actuators provides an enhanced dampening capability to the composite structure. The extent of crystallinity of the reinforcing actuators is found to directly influence the vibration dampening capacity.

scholarly journals Waterproofing material for protection of underground structures

2019 ◽  
Vol 97 ◽  
pp. 02008
Author(s):  
Olga Lyapidevskaya
Keyword(s):  
Crack Resistance ◽  
Mechanical Characteristics ◽  
Physical And Mechanical Properties ◽  
Ethylene Vinyl Acetate ◽  
Hard Coatings ◽  
Optimal Composition ◽  
Underground Structures ◽  
High Elasticity ◽  
Main Disadvantage ◽  
Physical And Mechanical Characteristics

The article deals with the problem of increasing the durability of underground and buried buildings. One of the methods of solving this problem is ensuring the reliable protection of underground structures from the effects of water of different origin. Among the existing waterproofing coatings, mineral-based compositions are the most effective. However, the main disadvantage of such systems is the low crack resistance of hard coatings, which limits their applicability. We have made an attempt to develop a cement-based waterproofing material that would have high elasticity, strength, crack resistance and adhesion to a concrete base. We have conducted studies to justify the possibility of obtaining an effective waterproofing material by including microsilica and ethylene vinyl acetate in the mix. The optimal composition of the material was worked out. On the basis of the experimental data, the main physical and mechanical properties of the material were established. Based on the obtained results, it was found that the resulting material had high physical and mechanical characteristics and could be recommended for the protection of concrete structures used in underground construction.

scholarly journals Experimental Study on Mechanical Characteristics and Fracture Patterns of Unfrozen/Freezing Saturated Coal and Sandstone

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 992 ◽  
Author(s):  
Chong Wang ◽  
Shuangyang Li ◽  
Tongwei Zhang ◽  
Zhemin You
Keyword(s):  
Phase Transition ◽  
Compressive Strength ◽  
Mechanical Characteristics ◽  
Failure Modes ◽  
Single Plane ◽  
Failure Patterns ◽  
Freezing Method ◽  
Fracture Patterns ◽  
Triaxial Compressive Strength ◽  
Layer Activation

The thermomechanical behavior of coal and sandstone during excavation using the freezing method is a new challenge for coal mining and geotechnical engineering. In this paper, the influence of temperature on the mechanical characteristics and fracture patterns of two types of saturated rocks (coal and sandstone) were investigated. A series of laboratory tests, including the Brazilian tensile strength (BTS), uniaxial compressive strength (UCS), and triaxial compressive strength (TCS), were conducted at temperatures of 20, −4, −10, and −15 °C. The results indicated a significant increase in their strength when the temperature was reduced from 20 to −15 °C, especially near the phase-transition point. Then, a theoretical model was proposed to predict rock strength change with temperature, based on the phase-transition theory. To evaluate this model, the predicted results were compared with experimental data, where a good correlation was identified. In addition, four failure patterns were observed in indirect tensile tests (i.e., layer activation, central fracture, noncentral fracture, and central and layer activation), and three types of failure modes in compression tests (i.e., axial splitting, shearing along a single plane, multiple fracturing). The evolution of the rock damage was divided into four stages: Crack closure, fracture initiation, critical energy release, and rupture. These results could be applied to evaluate and predict the mechanical behavior of saturated coal and sandstone during excavation using the freezing method.

Local Mechanical Characterization of Human Teeth by Instrumented Indentation

2010 ◽  
Vol 89-91 ◽  
pp. 751-756 ◽  
Author(s):  
Ilaria Cappelloni ◽  
Paolo Deodati ◽  
Roberto Montanari ◽  
Andrea Moriani
Keyword(s):  
Mechanical Characteristics ◽  
Mechanical Characterization ◽  
Damping Factor ◽  
Good Resolution ◽  
Instrumented Indentation ◽  
Mechanical Spectroscopy ◽  
Human Teeth ◽  
Indentation Tests ◽  
Cylindrical Punch

The mechanical characteristics of dentine have been investigated on local scale by micro-hardness and instrumented indentation tests. FIMEC, an indentation technique employing a cylindrical punch, permitted measurements of elastic modulus, yield stress, stress-relaxation and creep. The punch diameter (Φ = 0.5 mm) is much larger than the tubule size thus data are not so largely scattered as in micro- and nano-indentation tests but, at the same time, is small enough to guarantee a good resolution in mapping the mechanical properties in different tooth positions. The results are in agreement with literature data obtained by means of various experimental techniques. Furthermore, through tests of mechanical spectroscopy carried out on bar-shaped samples (13 mm x 4 mm x 0.8 mm) the dynamic modulus and the damping factor Q-1 have been measured.

scholarly journals PENELITIAN TRANSMISIBILITAS ALAT PEREDAM GETARAN PADA MUATAN ROKET RX 550 LAPAN (RESEARCH TRANSMISSIBILITY OF VIBRATION DAMPERS EQUIPMENTS ON ROCKET RX 550 LAPAN)

2018 ◽  
Vol 15 (2) ◽  
pp. 133
Author(s):  
Agus Budi Djatmiko
Keyword(s):  
Large Amplitude ◽  
Structural Engineering ◽  
Combustion Process ◽  
Vibration Damping ◽  
Electronic Equipment ◽  
Damping Factor ◽  
Engineering Structure ◽  
Single Piece ◽  
Working Frequency ◽  
Vibration Dampers

Every single piece of structural engineering as well as the rocket payload, has its mass and elasticity, and also has the potential to cause vibration. In general, the occurrence of vibration in the engineering structure is not desirable. Therefore, to the extent possible the vibrations is arranged to be muted. Acceleration nuisance caused by the combustion process in rocket can cause vibrations with a large amplitude resulting in damage to the structure of the mutant rockets and electronic equipment that is in charge of the rocket could not work as intended, based on the experience of electronic equipment will be damaged if the acceleration bully at 10 g that work on the rocket is not reduced, it is designed for a vibration damping apparatus, equipment consisting of springs and dampers are arranged such that a damping effecton the vibration occurs.In this research used springs with stiffness k = 120,000 N/m, damping factor = 0.0503 and mass of charge (m) = 10.5 kg, with acceleration of 1 G and working frequency from 0 to 2000 Hz. Interest transmissibility research on tool vibration dampers is to determine the magnitude of the acceleration is transmitted to the rocket payload. The results of the dampening experiment, at the beginning of acceleration or G force transmitted to a rocket load of 1 g or TR = 1, but after passing a resonance or obtained G force transmitted to a rocket payload of  0,1 g or TR = 0.1 (the silencer is good enough). From the results of this study can be said that the silencer can be used to reduce vibration on the rocket payload RX 550. AbstrakSetiap struktur rekayasa seperti halnya pada muatan roket, mempunyai massa dan elastisitas, maka struktur tersebut mempunyai potensi untuk menimbulkan getaran. Pada umumnya terjadinya getaran pada struktur rekayasa adalah tidak diinginkan, oleh karena itu sedapat mungkin getaran tersebut diusahakan untuk diredam. Percepatan pengganggu yang ditimbulkan oleh proses pembakaran pada roket dapat menyebabkan getaran dengan amplitudo yang besar yang mengakibatkan kerusakan  pada struktur mutan roket dan alat elektronik yang ada pada muatan roket sehingga tidak dapat bekerja seperti yang diinginkan. Berdasarkan pengalaman, alat elektronik akan mengalami kerusakan jika percepatan pengganggu sebesar 10 g yang bekerja pada roket tidak direduksi. Untuk itu dirancang suatu alat peredam getaran, peralatan tersebut terdiri dari pegas dan damper atau peredam yang disusun sedemikian rupa sehingga muncul efek redaman terhadap getaran. Pada penelitian ini digunakan pegas dengan kekakuan k = 120.000 N/m, faktor redaman  = 0,0503 dan massa muatan (m) = 10,5 kg, dengan percepatan sebesar 1 G dan frekuensi kerja dari 0 sampai dengan 2000 Hz. Tujuan penelitian transmisibilitas pada alat peredam getaran ini adalah untuk mengetahui besarnya percepatan yang ditransmisikan ke muatan roket. Hasil penelitian alat peredam, pada saat awal percepatan pengganggu atau G force yang ditransmisikan ke muatan roket sebesar 1 g atau TR = 1, tetapi setelah melewati resonansi atau  didapat G force yang ditransmisikan ke muatan roket sebesar  0,1 g atau TR = 0,1 (alat cukup baik). Dari hasil penelitian ini  dapat  dikatakan bahwa alat peredam dapat digunakan untuk meredam  getaran pada muatan roket RX 550.

scholarly journals Evaluation of TLCD Damping Factor from FRF Measurement Due to Variation of the Fluid Viscosity

2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Lovely Son
Keyword(s):  
Experimental Data ◽  
Frequency Response ◽  
Frequency Response Function ◽  
Low Frequency ◽  
Maintenance Cost ◽  
Damping Factor ◽  
Fluid Viscosity ◽  
Low Frequency Vibration ◽  
Main Disadvantage ◽  
Shear Structure

<p class="TTPAbstract">Tuned Liquid Column Damper (TLCD) has become an alternative solution for reducing low frequency vibration response of machines and structures. This is not surprisingly that the damper has simply structure and low maintenance cost. The main disadvantage of using TLCD is the complexity in controlling TLCD damping factor experimentally. Theoretically, damping factor can be controlled by adjusting the orifice dimension. However, this method is time consuming and not appropriate conducted in the real application. A more simply method for adjusting TLCD damping factor is by varying the fluid viscosity. This research is aimed to evaluate the effect of fluid viscosity to the damper performance. Two DOF shear structure with TLCD is used as the experimental model. Several TLCD fluids with different viscosity are evaluated. Evaluation of TLCD damping factor due to variation of the fluid viscosity is conducted by comparing the Frequency Response Function (FRF) obtained from the experimental data.</p>

Vibration-Damping Factor of Glass/Kenaf/Polyester Hybrid Composite

2018 ◽  
Vol 772 ◽  
pp. 38-42 ◽  
Author(s):  
Kuncoro Diharjo ◽  
Didik Djoko Susilo ◽  
Petrus Heru Sudargo ◽  
Sunarto Kaleg
Keyword(s):  
Elastic Modulus ◽  
Hybrid Composite ◽  
Volume Fraction ◽  
Unsaturated Polyester ◽  
Vibration Damping ◽  
Fiber Content ◽  
Damping Factor ◽  
Fiber Volume ◽  
Kenaf Fiber ◽  
Kenaf Fibers

The study of vibration-damping factor on unsaturated polyester resin reinforced glass and kenaf fiber has been performed. Two variations of glass and kenaf fibers were made based on fiber volume fraction (Vf) and ratio of glass to kenaf fiber at Vf of 25 %. The measurement of the samples was to obtain the value of the vibration-damping factor and the elastic modulus. The result shows that the vibration-damping factor decreases proportionally to the addition of fiber. Increased stiffness is evidenced by an increase in elastic modulus along with an increase in fiber content. According ratio of glass to kenaf fiber, the vibration-damping factor decreases proportionally with the increasing of glass fiber content. Increased kenaf fiber content causes an increase in vibration-damping factor, a decrease in elastic modulus, and lead to decreased in stiffness of the hybrid composite.

scholarly journals Evaluation of TLCD Damping Factor from FRF Measurement Due to Variation of the Fluid Viscosity

2016 ◽  
Vol 1 ◽  
Author(s):  
Lovely Son
Keyword(s):  
Experimental Data ◽  
Frequency Response ◽  
Frequency Response Function ◽  
Low Frequency ◽  
Maintenance Cost ◽  
Damping Factor ◽  
Fluid Viscosity ◽  
Low Frequency Vibration ◽  
Main Disadvantage ◽  
Shear Structure

<p class="TTPAbstract">Tuned Liquid Column Damper (TLCD) has become an alternative solution for reducing low frequency vibration response of machines and structures. This is not surprisingly that the damper has simply structure and low maintenance cost. The main disadvantage of using TLCD is the complexity in controlling TLCD damping factor experimentally. Theoretically, damping factor can be controlled by adjusting the orifice dimension. However, this method is time consuming and not appropriate conducted in the real application. A more simply method for adjusting TLCD damping factor is by varying the fluid viscosity. This research is aimed to evaluate the effect of fluid viscosity to the damper performance. Two DOF shear structure with TLCD is used as the experimental model. Several TLCD fluids with different viscosity are evaluated. Evaluation of TLCD damping factor due to variation of the fluid viscosity is conducted by comparing the Frequency Response Function (FRF) obtained from the experimental data.</p>

scholarly journals (318) The Flat Bed Scanner as a Close-up Digital Camera

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1044E-1044
Author(s):  
James McConnell
Keyword(s):  
Plant Material ◽  
Digital Camera ◽  
Depth Of Field ◽  
Image Editing ◽  
Instructional Tool ◽  
Single Plane ◽  
Plant Pests ◽  
Main Disadvantage ◽  
Flat Bed Scanner

A flat bed scanner can be used as a high-resolution digital camera with close-up capabitlities for photographing plant material such as leaves, flowers, and plant pests. The scanner is very useful as a diagnostic and instructional tool that is more portable and less expensive than a camera and dissecting microscope. The quality of the images can be very good and can be enhanced in post-production using image editing software. The main disadvantage is the shallow depth of field, which requires the object be on a single plane.

Effects of an 8-week basketball-specific proprioceptive training with a single-plane instability balance platform

2020 ◽  
Vol 28 (5) ◽  
pp. 561-571
Author(s):  
Aurelijus Domeika ◽  
Agnė Slapšinskaitė ◽  
Selen Razon ◽  
Laimonas Šiupšinskas ◽  
Irina Klizienė ◽  
...  
Keyword(s):  
Training Program ◽  
Postural Stability ◽  
Balance Training ◽  
Stability Test ◽  
Control Group ◽  
Training Methods ◽  
Basketball Players ◽  
Balance Test ◽  
Single Plane ◽  
Balance Ability

BACKGROUND: To avoid injuries in basketball players, they are recommended to pay more attention to improve their body balance. Therefore new training methods and equipment need to be devised. This study examined the effects of an 8-week basketball-specific proprioception training program while using a new developed one plane instability balance board during warm-up for improving balance ability in basketball players. Players who obtained basketball-specific balance training were compared to a control group. METHODS: Thirty-one male university basketball players (age: 21.35, SD = 0.605 years; height: 190.97, SD = 1.88; body mass: 86.95, SD = 2.61) participated in this study. Seventeen participants were assigned to the basketball-specific 8-week balance training group (BTG) while 14 participants served as a control group (CG). Both groups were tested with the Y balance test (YBT) and postural stability test (PST) at baseline and 8 weeks later. RESULTS: The results indicate significant improvements in the overall YBT for both legs in BTG, but not in CG. However, no group differences were found for dynamic balance performance, but static balance (i.e., postural stability) differed between groups after 8 weeks. A statistically significant moderate inverse correlation was computed between the total score of YBT and the total score of the overall stability index (r=-0.404; p= 0.041). CONCLUSIONS: An 8-week basketball-specific proprioception training program with a single-plane instability balance platform improved balance ability (Y balance test and postural stability test) of basketball players.

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