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Hideaki Suda - One of the best experts on this subject based on the ideXlab platform.

  • phase transformation behaviour and Bending property of twisted nickel titanium endodontic instruments
    International Endodontic Journal, 2011
    Co-Authors: Y Yahata, Y Hayashi, Takao Hanawa, Arata Ebihara, Hideaki Suda
    Abstract:

    AIM: To investigate the relationship between phase transformation behaviour and Bending property of nickel-titanium endodontic instruments manufactured by a twisting process. METHODOLOGY: The phase transformation behaviour and Bending property of Twisted Files (TF; SybronEndo, Orange, CA, USA) and K3 (SybronEndo) with.06 taper and size 30 tip were investigated. K3 was used as control group. Phase transformation behaviour was estimated by differential scanning calorimetry (DSC). Transformation temperatures were calculated from the DSC curve. Bending Load of the instruments was measured by cantilever-Bending test at 37°C. Data were analysed by Student's t-test and Mann-Whitney U-test. RESULTS: The phase transformation temperatures of TF were significantly higher (P<0.05) than those of K3. The Bending Load values were significantly lower for TF than that of K3 (P<0.05), both in the elastic and super-elastic ranges. CONCLUSIONS: The new method of manufacturing NiTi instruments by twisting coupled with heat treatment might contribute to the increased phase transformation temperatures and superior flexibility.

  • phase transformation behaviour and Bending properties of hybrid nickel titanium rotary endodontic instruments
    International Endodontic Journal, 2007
    Co-Authors: Y Hayashi, Takayuki Yoneyama, Y Yahata, K Miyai, Takao Hanawa, Arata Ebihara, Hideaki Suda
    Abstract:

    Aim  To investigate the Bending properties of hybrid rotary nickel–titanium endodontic instruments in relation to their transformation behaviour. Methodology  Four types of nickel–titanium rotary endodontic instruments with different cross-sectional shapes (triangular-based and rectangular-based) and different heat treatment conditions (super-elastic type and hybrid type with shape memory effect) were selected to investigate Bending properties and phase transformation behaviour. Bending Load of the instruments was measured in a cantilever-Bending test at 37 °C with the maximum deflection of 3.0 mm. A commercial rotary instrument, ProFile (PF; Dentsply Maillefer, Ballaigues, Switzerland) was used as a reference for the Bending test. Phase transformation temperatures were calculated from the diagrams obtained from differential scanning calorimetry. Data were analysed by anova and Scheffe's test. Results  The Bending Load values of the hybrid type that had undergone additional heat treatment at the tip were significantly lower (P < 0.05) than those of the super-elastic type with no additional heat treatment. The Bending Load values of rectangular-based cross-sectional shaped instruments were significantly lower (P < 0.05) than those of triangular-based cross-sectional shaped instruments. Phase transformation temperatures (Ms and Af points) of the hybrid type were significantly higher (P < 0.05) than the super-elastic type. The Mf and As points of the tip part were significantly higher (P < 0.05) than those of the whole part of the hybrid instrument. Conclusions  Additional heat treatment of hybrid nickel–titanium instruments may be effective in increasing the flexibility of nickel–titanium rotary instruments.

Klaus Dilger - One of the best experts on this subject based on the ideXlab platform.

  • Study on the residual stress relaxation in girth-welded steel pipes under Bending Load using diffraction methods
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017
    Co-Authors: Nico Hempel, Th Nitschke-Pagel, Jeffrey R. Bunn, E. Andrew Payzant, Klaus Dilger
    Abstract:

    Abstract This research is dedicated to the experimental investigation of the residual stress relaxation in girth-welded pipes due to quasi-static Bending Loads. Ferritic-pearlitic steel pipes are welded with two passes, resulting in a characteristic residual stress state with high tensile residual stresses at the weld root. Four-point Bending is applied to generate axial Load stress causing changes in the residual stress state. These are determined both on the outer and inner surfaces of the pipes, as well as in the pipe wall, using X-ray and neutron diffraction. Focusing on the effect of tensile Load stress, it is revealed that not only the tensile residual stresses are reduced due to exceeding the yield stress, but also the compressive residual stresses for equilibrium reasons. Furthermore, residual stress relaxation occurs both parallel and perpendicular to the applied Load stress.

Xibin Wang - One of the best experts on this subject based on the ideXlab platform.

  • crack behavior of ti 6al 4v alloy combined conformal contact fretting non conformal contact fretting and simple fatigue
    International Journal of Fatigue, 2020
    Co-Authors: Huiqing Gu, Lvchen Feng, Li Jiao, Shiqi Chen, Xibin Wang
    Abstract:

    Abstract This paper presents the results of fatigue tests combined with conformal contact, non-conformal contact and simple fatigue carried out on Ti-6Al-4V sheet specimens under externally remote Bending Load. A special fretting fatigue test rig was proposed to focus on two different fretting modes fatigue test simultaneously between non-conformal contact and conformal contact. The test results showed that all the specimens failed at the conformal contact area under external Bending Load, although the contact stress was lower, residual stress was higher than that with non-conformal contact area. The reason for failure was radial fretting induced fatigue depending upon the nature of conformal geometry. The conformal geometric nature reversed the contact shear stress, accelerated the debris accumulation, redistributed the contact Loading and exacerbated the crack nucleation conditions. The mechanisms of fretting fatigue crack formation, including crack nucleation and the three stages of crack propagation were discussed. Furthermore, among the four regions (fretting region, protrusion region, dark inner friction region and fracture region) on fractography, the protrusion region and dark inner friction region were special, rarely reported before. To explain the formation of the protrusion region, dark inner friction region, internal crack and stripped material on the fractography, a friction-based press-push-separate procedure interpretation was proposed. In addition, crack arresting effect exists in the propagation of fretting fatigue cracks due to compression Loading on the contact surface with non-conformal contact.

Palla Gandhi - One of the best experts on this subject based on the ideXlab platform.

  • fatigue crack growth behavior of a 170 mm diameter stainless steel straight pipe subjected to combined torsion and Bending Load
    Frontiers of Structural and Civil Engineering, 2021
    Co-Authors: Selvakumar Veerarajan, Dakshinamurthy Pukazhendhi, Palla Gandhi
    Abstract:

    In a nuclear powerplant, the rotary equipment, such as a pump directly fitted with hanger in the piping system, experiences torsional and Bending Loads. Higher crack growth rate occurs because of this torsional Load in addition to the Bending Load. Hence, it is necessary to study the fatigue behavior of piping components under the influence of combined torsional and Bending Load. In this study, experimental fatigue life evaluation was conducted on a notched stainless steel SA312 Type 304LN straight pipe having an outer diameter of 170 mm. The experimental crack depth was measured using alternating current potential drop technique. The fatigue life of the stainless steel straight pipe was predicted using experiments, Delale and Erdogan method, and area-averaged root mean square-stress intensity factor approach at the deepest and surface points of the notch. Afterward, the fatigue crack growth and crack pattern were discussed. As a result, fatigue crack growth predicted using analytical methods are in good agreement with experimental results.

Naseem Abbas - One of the best experts on this subject based on the ideXlab platform.

  • experimental and computational studies on honeycomb sandwich structures under static and fatigue Bending Load
    Journal of King Saud University - Science, 2019
    Co-Authors: Muzamil Hussain, Rafiullah Khan, Naseem Abbas
    Abstract:

    Abstract Sandwich structures with glass fiber face sheets and aluminum honeycomb core are investigated computationally and experimentally. A three point Bending Load arrangement is conducted to examine the static and fatigue performance of honeycomb sandwich panel. Under static Loading, the Load and displacement response is indicated in five phases. The decrease in fatigue life with Load level was observed in approximately linear manner. The visual and Scanning Electron Microscopic (SEM) analysis were carried out to analyze the failure modes. For static and high amplitude fatigue Load, the failure initiates due to face yielding, while for low fatigue Load failure initiates as a result of delamination at core and skin interface. However, in all cases principle failure mode is indentation. The honeycomb sandwich structure was also modeled with commercially available finite element packages ANSYS and the fatigue analyses were carried out to determine the life of specimens under Load-displacement response. The experimental results were in good agreement with the Finite Element Analysis (FEA) results in both static and fatigue Loads, and fracture modes prediction.

  • Experimental and computational studies on honeycomb sandwich structures under static and fatigue Bending Load
    Elsevier, 2019
    Co-Authors: Muzamil Hussain, Rafiullah Khan, Naseem Abbas
    Abstract:

    Sandwich structures with glass fiber face sheets and aluminum honeycomb core are investigated computationally and experimentally. A three point Bending Load arrangement is conducted to examine the static and fatigue performance of honeycomb sandwich panel. Under static Loading, the Load and displacement response is indicated in five phases. The decrease in fatigue life with Load level was observed in approximately linear manner. The visual and Scanning Electron Microscopic (SEM) analysis were carried out to analyze the failure modes. For static and high amplitude fatigue Load, the failure initiates due to face yielding, while for low fatigue Load failure initiates as a result of delamination at core and skin interface. However, in all cases principle failure mode is indentation. The honeycomb sandwich structure was also modeled with commercially available finite element packages ANSYS and the fatigue analyses were carried out to determine the life of specimens under Load-displacement response. The experimental results were in good agreement with the Finite Element Analysis (FEA) results in both static and fatigue Loads, and fracture modes prediction. Keywords: Sandwich structures, Bending Load, Finite element, Fatigue life, Failure modes, Face yieldin