• Title/Summary/Keyword: Tension deviation

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Effects of Abdominal Muscle and Pressure on the Spine Stability during Upright Stance Posture - For the Case where Intervertebral Disc Plays the Role of Mechanoreceptor (추간판이 물리적 자극의 수용기 역할을 하는 경우 기립 상태에서 복압 및 복근의 역할이 척추 안전성에 미치는 영향)

  • Choi, Hae-Won;Kim, Young-Eun
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.1
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    • pp.115-122
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    • 2011
  • Recently, we have proposed a hypothesis that spinal structures have a stress sensor driving feedback mechanism, In the human spine, spinal structure could react to modify muscular action in such a way so as to equalize stress at the disc, therefore reduce the risk of injury, In this analysis, abdominal muscle and abdominal pressure, which were not included in the previous study, were added to identify those effects in spine stability during upright stance posture for the case where the intervertebral disc plays the role of mechanoreceptor, The musculoskeletal FE model was consisted with detailed whole lumbar spine, pelvis, sacrum, coccyx and simplified trunk model. Muscle architecture with 46 local muscles containing paraspinal muscle and 6 rectus abdominal muscles were assigned according to the acting directions. The magnitude of 4kPa was considered for abdominal pressure. Minimization of the nucleus pressure deviation and annulus fiber average tension stress deviation was chosen for cost function. Developed model provide nice coincidence with in-vivo measurement (nucleus pressure). Analysis was conducted according to existence of co-activation of abdominal muscle and abdominal pressure. Antagonistic activity of abdominal muscle produced stability of spinal column with relatively small amount of total muscle force. In contrast to the abdominal muscle, effect of abdominal pressure was not clear that was partly depending on the assumption of constant abdominal pressure.

Analysis of Springback of Sheet Metal(II): Experimental Validation of Analytical Model (박판재의 스프링백 해석(II)-해석모델의 실험적 검증)

  • Lee, Jae-Ho;Kim, Dong-Woo;Sohn, Sung-Man;Lee, Mun-Yong;Moon, Young-Hoon
    • Transactions of Materials Processing
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    • v.16 no.7
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    • pp.516-520
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    • 2007
  • As the springback of sheet metal during unloading nay cause deviation from a desired shape, accurate prediction of springback is essential for the design of sheet stamping operations. On the removal of the applied load the specimen loses its elastic strain by contracting around the contour of the block, the radius $\rho$ can be determined by the residual differential strain. Therefore in this study the springback estimated by the residual differential strain is experimentally validated through the comparison with those obtained by U-bending test. The springback characteristics of two analytical models are also estimated at various processing conditions such as thickness, curvature of radius and drawing strain. The model based on residual differential strain has an applied transition strain where the springback undergoes a dramatic decrease. Both models show that springback decreases with increased strip thickness and with decreased radius of curvature. For no applied tension, the model based on residual differential strain predicts more springback as compared to the moment based model.

Empirical study of alginate impression materials by customized proportioning system

  • Kurtulus, Karani;Tufekci, Kenan
    • The Journal of Advanced Prosthodontics
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    • v.8 no.5
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    • pp.372-379
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    • 2016
  • PURPOSE. Alginate mixers available in the market do not have the automatic proportioning unit. In this study, an automatic proportioning unit for the alginate mixer and controller software were designed and produced for a new automatic proportioning unit. With this device, it was ensured that proportioning operation could arrange weight-based alginate impression materials. MATERIALS AND METHODS. The variation of coefficient in the tested groups was compared with the manual proportioning. Compression tension and tear tests were conducted to determine the mechanical properties of alginate impression materials. The experimental data were statistically analyzed using one way ANOVA and Tukey test at the 0.05 level of significance. RESULTS. No statistically significant differences in modulus of elastisity (P>0.3), tensional/compresional strength (P>0.3), resilience (P>0.2), strain in failure (P>0.4), and tear energy (P>0.7) of alginate impression materials were seen. However, a decrease in the standard deviation of tested groups was observed when the customized machine was used. To verify the efficiency of the system, powder and powder/water mixing were weighed and significant decrease was observed. CONCLUSION. It was possible to obtain more mechanically stable alginate impression materials by using the custom-made proportioning unit.

Clinical analysis of early reoperation cases after orthognathic surgery (악교정수술 후 조기 재수술 증례의 분석)

  • Lee, Ju-Hwan;Lee, In-Woo;Seo, Byoung-Moo
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.36 no.1
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    • pp.28-38
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    • 2010
  • The factors influencing the relapse and recurrence of skeletal deformity after the orthognathic surgery include various factors such as condylar deviation, the amount of mandibular set-back, stretching force by the soft tissues and muscles around the facial skeleton. The purpose of this report is to recognize and analyze the possible factors of reoperation after orthognathic surgery, due to early relapses. Six patients underwent reoperation after the orthognathic surgeries out of 110 patients from 2006 to 2009 were included in this study. In most cases, clincal signs of the insufficient occlusal stability, anterior open bite, and unilateral shifting of the mandible were founded within 2 weeks postoperatively. Although elastic traction was initiated in every case, inadequate correction made reoperation for these cases inevitable. The chief complaints of five cases were the protruded mandible combined with some degree of asymmetric face and in the other one case, it was asymmetric face only. Various factors were considered as a major cause of post-operative instability such as condylar sagging, counter-clockwise rotation of the mandibular segment, soft tissue tension related with asymmetrical mandibular set-back, preoperatively existing temporomandibular disorder (TMD), poor fabrication of the final wafer, and dual bite tendency of the patients.

The effect of plastic anisotropy on wrinkling behavior of sheet metal (소성 이방성이 박판의 주름 발생에 미치는 영향)

  • 양동열
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.03b
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    • pp.14-17
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    • 1999
  • The wrinkling behavior of a thin sheet with perfect geometry is a kind of compressive instability. The compressive instability is influenced by many factors such as stress state mechanical properties of the sheet material geometry of the body contact conditions and plastic anisotropy. The analysis of compressive instability in plastically deforming body is difficult considering all the factors because the effects of the factors are very complex and the instability behavior may show wide variation for small deviation of the factors. In this study the bifurcation theory is introduced for the finite element analysis of puckering initiation and growth of a thin sheet with perfect geometry. All the above mentioned analysis and the post-bifurcation behavior is analyzed by introducing the branching scheme proposed by Riks. The finite element formulation is based on the incremental deformation theory and elastic-plastic material modeling. in order to investigate the effect of plastic anisotropy on the compressive instability a square plate that is subjected to compression in one direction and tension in the other direction is analyzed by the above-mentionedfinite element analysis. The critical stress ratios above which the buckling does not take place are found for various plastic anisotropic modeling method and discussed. Finally the effect of plastic anisotropy on the puckering behavior in the spherical cup deep drawing process is investigated.

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Suspension Stability of Pigments in Aqueous Solution of Anionic Oligo-Type Surfactants(part 3);Synthesis of Anionic Oligo Surfactant having Fluorescent Intensity and Their Properties (올리고머형 음이온성계면활성제 수용액에서 안료의 분산안정성(제 3보);형광성이 큰 올리고머 계면활성제의 합성 및 그의 계면성)

  • Lee, H.W.;Lee, J.H.;Ju, M.J.;Nam, K.D.
    • Journal of the Korean Applied Science and Technology
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    • v.14 no.1
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    • pp.109-115
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    • 1997
  • Fluorescent anionic oligo surfactants were synthesized by the condensing products of long chain alkylvinylether-maleic anhydride cooligomers and resorcinol including dye structures. Their various surface activities and dispersing action were studied on the aqueous solution. These oligo surfactants exhibited a remarkable surface tension lowering property, lower foaming and a large dispersing action for the particles of ${\alpha}-copper$ phthalocyanine blue. Further it was ascertained that the binding of oligo surfactant onto the pigment surface caused the deviation towards lower wavelengths at the maximum fluorescent intensity as compared with aqueous oligo surfactant solutions, These surface active properties of the oligo surfactants may be attributed to rigid and hydrophobic structure of dye groups, besides surface-active groups of alkylether groups and carboxylic group of the anionic oligo surfactants.

Flow Behavior of Thin Polymer Film by various patterns in Spinning Coating Process of Blu-ray Disc Cover layer (블루레이 디스크의 커버레이어 스핀 코팅 시 다양한 패턴에 따른 최적화된 폴리머 거동에 관한 연구)

  • Cho K. C.;Park Y. H.;Kim H. Y.;Kim B. H.;Lee B. G.;Son S. G.;Shin H. K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.467-471
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    • 2005
  • In this paper, experimental methods about the flow behavior of thin polymer film by various edge patterns in the spin coating process for stable cover layer coating of a blu-ray disc is described. The blu-ray disc, a next-generation optical disc format over 25GB, consists of a 1.1m thick substrate and a 0.1mm tick cover layer. Generally, cover layer on the blu-ray disc is made by the polymer spin coating process. However, it is hard to secure sufficient coating uniformity around the rim on the cover layer. In order to get the uniform thickness deviation and to minimize the bead around the rim, the edge of the disc substrate can be modified into various patterns, such as normal plain, trench, step and chamfer pattern, etc, around the rim on the disc and experimented with various parameters, such as surface tension, viscosity, coating time, temperature and rotation speed, etc. And the optimal shape of the rim was tried to get by 3 dimensional computer simulation of the polymer expulsion process.

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The Joining Quality of High Strength Bolt, Nut and Washer Set (S10T & 10.9HRC) under the Surface Treatment Conditions (표면처리별 S10T, 10.9HRC 고장력 볼트 세트의 체결 품질 연구)

  • Choi, Youn-O;Suk, Han-Gil;Hong, Hyeon-Sun
    • Journal of the Korean institute of surface engineering
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    • v.48 no.3
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    • pp.93-99
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    • 2015
  • This test focuses on the correlations between joining axial force at non-room temperature and at room temperature according to the surface treatment (Geomet, Dacro, Green Kote, Armore Galv.). The quality characteristics of the fastening axial force required by the KSB 2819 and EN14399-10 standards were discussed. Surface treatment was implemented to S10T and 10.9HRC sets of bolts under the same environmental factors. Development for the stabilization of the fastening axial force required by each standard should continually be enforced, and the fastening and storage in the field should be maintained at room temperature. Managing stabilization of torque enumerated data is required after application of surface treatment. It is concluded that, by conducting the test of applying surface treatment to effectively manage, each lot-specific rate of axial force at room temperature conditions should be maintained below the maximum 4.47%. The decline rate of axial force should be maintained under 2.15% maximum, and the standard deviation of the room temperature condition should be maintained below 0.5.

Flow Behavior of Thin Polymer Film in Spinning Coating Process of Blu-ray Disc Cover layer (블루레이 디스크의 커버레이어 스핀코팅 시 폴리머 거동에 관한 연구)

  • Ban J. H.;Shin H. G.;Kim B. H.;Kim H. Y.;Lee H. G.;Son S. G.;Shin J. K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.113-116
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    • 2005
  • In this paper, a computational and experimental analysis about the flow behavior of thin polymer film in the spin coating process for stable cover layer coating of a blu-ray disc is described. The blu-ray disc, a next-generation optical disc format over 25GB, consists of a 1.1mm thick substrate and a 0.1mm tick cover layer. Generally, cover layer on the blu-ray disc is made by the polymer spin coating process. However, it is hard to secure sufficient coating uniformity around the rim on the cover layer. In order to get the uniform thickness deviation and to minimize the bead around the rim, the edge of the disc substrate can be modified into various shapes around the rim on the disc and analyzed with various parameters, such as surface tension, viscosity, and rotation speed, etc. The optimal shape of the rim was tried to get by 3 dimensional computer simulation of the polymer expulsion process.

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Fatigue behavior of mechanical structures welded with different filler metal

  • Alioua, Abdelkader;Bouchouicha, Benattou;Zemri, Mokhtar;IMAD, Abdellatif
    • Advances in materials Research
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    • v.6 no.3
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    • pp.233-243
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    • 2017
  • This paper describes an investigation on the effect of using three different filler metals on fatigue behavior of mechanical structures welded. The welding is carried out on the steel A510AP used for the manufacture of gas cisterns and pipes. The welding process used is manual welding with coated electrodes and automatic arc welding. Compact tension CT50 specimen has been used. The three zones of welded joint; filler metal FM, heat affected zone HAZ and base metal BM have been investigated. The results show that the crack growth rate CGR is decreasing respectively in BM, FM and HAZ; however, this variation decreases when stress intensity factor SIF increases. For low values of SIF, the CGR is inferior in the over-matched filler metal of which the value of mismatch M is near unity, but for high values of M the CGR is superior, and the effect of the over-matching on CGR becomes negative. No deviation of the crack growth path has been noticed.