Shear Force Loading Research Articles

Shear and Bending Stresses in Prismatic, Non-Circular-Profile Shafts with Epitrochoidal Contours Under Shear Force Loading

Shear and Bending Stresses in Prismatic, Non-Circular-Profile Shafts with Epitrochoidal Contours Under Shear Force Loading

Surgery assistance system for continuous resection of brain tumors-proposal of continuous tumor resection forceps, tumor cell separation, dehydration, and isolation mechanism

The tumor resection ratio must be improved due the increased possibility of recurrence or malignancy. The purpose of this study was to develop a system that includes forceps with a continuous suction function and flow cytometry to diagnose the malignancy of the tumor for safe, accurate, and effective surgery. A newly developed continuous tumor resection forceps consists of a triple pipe structure, which enables continuous suction of the tumor by integrating the reflux water and suction system. The forceps includes tip opening/closure detection switch to control the adsorption and suction strength when tip is opened and closed. To perform accurate tumor diagnosis using flow cytometry, a filtering mechanism was developed for dehydrating reflux water from continuous suction forceps. In addition, a cell isolation mechanism comprising a roller pump and shear force loading mechanism was also newly developed. By using a triple pipe structure, a significantly larger tumor collection ratio was observed compared to the previous double-pipe structure. By performing suction pressure control with the opening/closure detection switch, inaccurate suction can be prevented. By widening the filter area of dehydration mechanism, it was possible to improve the reflux water dehydration ratio. The most appropriate filter area was 85 mm2. By using a newly developed cell isolation mechanism, the processing time can be reduced to less than 1/10 of the original time, keeping the same cell isolation ratio, when compared to the existing pipetting method. Neurosurgery assistance system with continuous tumor resection forceps and a cell separation, dehydration and isolation mechanism was developed. An effective and safe tumor resection, accurate and fast diagnosis of malignancy can be achieved by using the current system.

Improved design of a cone-shaped rotating disk for shear force loading in a cell culture plate

In our previous study, a cone-shaped rotating disk had been designed and proposed for generating shear force on the cell in a cell culture plate. This study aims to improve the design of the rotating disk that could provide a better uniformity of shear stress distribution. The top of the cone was designed to be trimmed off to obtain a flat head area. The effect of tilt angle (θ) was numerically studied using computational fluid dynamics (CFD) technique in ANSYS-Fluent software. The results revealed that for 500 rpm, the new designed rotating disk with a height of cone-shaped top to the plate bottom h = 1 mm and θ = 25° provided the best uniformity of 0.820 which was better than that of the previously designed.

通しダイアフラム形式の柱梁溶接接合部を設けた鋼梁の耐火性能

Verification on both load-bearing and plastic deformation capacity for a steel beam-column welded connection at elevated temperature is of importance to secure fire safety of steel building structures. At the fire resistant design, it is required that the beam-column welded connection does not fracture before the adjacent heated steel beam exhibits stable plastic collapse mechanism. The AIJ design recommendation (Architectural Institute of Japan, 2017) cannot, however, offer a fire resistant verification method for the beam-column welded connection, because the fire resistance has not been verified experimentally. Main purpose of this study is to clarify both load-bearing and deformation capacity for steel beams including the beam-column welded connections at high temperature, by conducting their experiments under a condition on constant temperature and gradually increasing load. The beam-column welded connection with through diagrams is arranged in the center of beam specimen. The boundary condition is simple support and a shear force is applied through the medium of the column above the beam-column welded connection. In the welded connection, scallop working for a web plate in the wide flange section is not used. This kind non-scallop working is widely used for the actual beam-column welded connections to avoid brittle fracture at the structural design in Japan. The base metal and weld material are JIS SN490B and JIS YGW11, respectively. Stiffener plates to avoid local buckling of the flange plate in the beam are arranged near the beam-column welded connection, because the large tensile force is acted to the welded connection. The number of specimens is five and an experimental parameter is specimen temperature, which is given by ambient temperature, 600, 700, 800 and 900 °C. The specimen temperature was gradually risen by an electric furnace, and the shear force was applied after the temperature reached to the test temperature and kept constant it. Bending moment and rotation angle of the specimen are estimated respectively, and the shear force loading continued until the rotation angle exceeded 0.2. From minute investigations on the experimental results, the following knowledge was obtained. All specimens exhibited the beam bending collapse mode and the welded connections did not fracture. They possessed the larger bending strength than the full plastic moment at each temperature. The shear force applied at the high temperature experiments approximately kept constant with the specimen plastic deflection increase. From specimen observation after those experiments, the weld metal itself in the beam-column connection besides the beam largely deformed, however, ductile cracks in the weld metal and heat affected zone were not observed. It is expected that the beam-column welded connection with the high seismic performance by the non-scallop working also possesses the high load-bearing and deformation capacity at the fire. Furthermore, in-plane numerical analyses using a beam element were conducted, and it was clarified that both numerical and experimental specimen behaviors approximately agreed.

Mode II delamination resistance of composites reinforced with inclined Z-pins

Z-pin reinforcements in composite materials significantly enhance the through-thickness strength by providing strong bridging forces on the delaminated surfaces of a damaged laminate. The bridging forces have been shown to be more effective in mode I dominated delamination cracks than in mode II shear dominated cracks. One solution to help improve the Mode II delamination resistance of Z-pins is to incline the pins such that the angle between the longitudinal axis of the pin and the shear force load vector is reduced. In this study, the Mode II resistance of laminated composite reinforced through the thickness with inclined Z-pins is characterised. There is a notable increase in the apparent fracture toughness of composites when Z-pins are better aligned with the shear load vector (inclined) compared to the conventional, orthogonally inserted Z-pins. Brittle, catastrophic failure however occurs when the inclined Z-pins are angled against the shear load vector. For many structures the direction of the local direction of shear load cannot always be predicted, therefore a general approach for inclined Z-pins using a±θ configuration was also investigated. With this setup, a modest improvement in the apparent fracture toughness was obtained.

Effects of temperature on the material characteristics of midsole and insole footwear foams subject to quasi-static compressive and shear force loading

The use of appropriate leisure, sports and orthotic footwear can help reduce the occurrence of foot problems, maintain correct gait and provide stability for the individual. The temperature of footwear components could play a key role in the development of foot problems in certain circumstances and can also affect gait and stability too.For orthotic and sports applications, footwear should be designed to accommodate the effects of temperature to maximise their cushioning and stabilizing effect. Materials test data is therefore required for footwear foams at various temperatures to predict their performance in service and to aid materials development and product design.The mechanical properties of eight commonly used elastomeric foams (midsole and insole) have been obtained from the current study and the effect of temperature quantified under displacement control test conditions. The foams were subject separately to quasi-static compression and shear force loading under varying temperature conditions (−10°C to 40°C) using a new testing protocol. All material test data were subject to a least squares fit procedure within the FEA software ABAQUS to determine the coefficients of the hyperfoam model used to describe the foams behaviour at different temperature, a validation exercise for these coefficients has been performed. Further numerical methods were employed to determine the foams energy absorption characteristics.The present study indicated that all foams tested exhibit typical elastomer mechanical and energy absorption characteristics and that these characteristics are affected significantly as a function of temperature. All foams demonstrated some degree of softening with elevated temperature whereas lower temperatures resulted in a greater amount of energy absorption capability for a specific value of strain (as a result of increasing stiffness).

Stiffness analysis of footwear foams subjected to shear force loading at varying temperatures

The temperature rise inside the footwear is due to the three main factors of foot temperature, repetitive friction between the foot and footwear and environmental temperature (Shariatmadari et al. ...

강상자형교의 전단력 산정을 위한 하중분배계수

강상자형사교의 경우 국내의 도로교 설계기준이 갖추어지지 않아, 미국의 AASHTO 및 AASHTO LRFD 설계기준을 적용할 경우에는 실제의 거동과 다른 하중분배계수를 산출하게 되어 과대설계 및 과소설계를 초래할 가능성을 가지고 있다. 본 연구의 목적은 실제 거동을 바탕으로 한 강상자형 사교의 둔각부 지점에서의 전단력 산정을 위한 하중분배계수식을 제시하는 데 있다. 이를 위하여 본 연구에서는 강상자형 사교의 다양한 구조모델들에 대해 유한요소해석을 수행하고, 각 매개변수들이 강상자형사교의 하중분배계수에 미치는 영향을 분석한 후, 다중회귀분석을 수행하여 강상자형사교의 전단력 산정을 위한 하중분배계수식을 제시한다. For Korean design provisions are not equipped for skewed steel box girder bridges, when American provisions are adopted, load distribution factors different from real behavior are determinated. Furthermore the possibility of over or under estimated bridge design involves. The aim of this study is to provide more rational load distribution factor formulas based on real behavior for shear at obtuse corner of skewed steel box girder bridges. In order to accomplish the aim finite element analysis for a variety of skewed steel box girder bridge structural models is carried out, and each parameters degree of influence on wheel load distribution factors of skewed steel box girder bridges are analyzed. Then multiple regression analysis is fulfilled in order to propose formulas for determinating shear force load distribution factor of skewed steel box girder bridges.

A technique for conditioning and calibrating force-sensing resistors for repeatable and reliable measurement of compressive force

Miniature sensors that could measure forces applied by the fingers and hand without interfering with manual dexterity or range of motion would have considerable practical value in ergonomics and rehabilitation. In this study, techniques have been developed to use inexpensive pressure-sensing resistors (FSRs) to accurately measure compression force. The FSRs are converted from pressure-sensing to force-sensing devices. The effects of nonlinear response properties and dependence on loading history are compensated by signal conditioning and calibration. A fourth-order polynomial relating the applied force to the current voltage output and a linearly weighted sum of prior outputs corrects for sensor hysteresis and drift. It was found that prolonged (>20 h) shear force loading caused sensor gain to change by approximately 100%. Shear loading also had the effect of eliminating shear force effects on sensor output, albeit only in the direction of shear loading. By applying prolonged shear loading in two orthogonal directions, the sensors were converted into pure compression sensors. Such preloading of the sensor is, therefore, required prior to calibration. The error in compression force after prolonged shear loading and calibration was consistently <5% from 0 to 30 N and <10% from 30 to 40 N. This novel method of calibrating FSRs for measuring compression force provides an inexpensive tool for biomedical and industrial design applications where measurements of finger and hand force are needed.

Investigation of filament distribution at geotextile/geomembrane interfaces

This paper presents results from a study that examined the filament distributions at needle-punched nonwoven (NPNW) geotextile/HDPE geomembrane interfaces. An advanced image analysis technique was used to observe the evolution of the filament microstructure under different boundary conditions including normal force loading and unloading, as well as shear force loading to residual conditions. The different phases within the geosynthetic interface zone were detected from images captured using high-resolution optical microscopy. The changes in geotextile inner structure were statistically quantified in terms of filament nearest neighbour distance distribution and local void ratio distribution. The frequency of geotextile features within 10 μm of the interface increased by 73% as the normal stress increased from 10 to 300 kPa. The filament concentration at filament-texture interlocking points was quantified in terms of the local void ratio distribution. The study provides insight into the mechanism of geotextile microstructure evolution under different boundary conditions.

On the numerical Green’s function technique for cracks in Reissner’s plates

The numerical Green’s function (NGF) technique, previously proposed by the present authors, is here extended to fracture mechanics problems involving Reissner’s plate theory. The technique numerically produces a plate bending fundamental Green’s function that automatically includes embedded cracks to be used in the classical boundary element method (BEM) to solve this class of problems. The applications discussed include torsion, bending moment and shear force loadings. In addition, also presented is a series of numerical results computed in terms of normalized stress intensity factors to illustrate the good accuracy of the procedure.

摩擦ダンパーＣＦＤを用いた戸建て住宅制震構法の開発

The authors of this paper have developed a earthquake force reduction system for the wooden houses. This contruction method involves the fixing of a friction damper in the form of a brace to the wooden frame using steel brackets and pipes for added damping effect. In order to confirm the damping properties of this earthquake force reduction system, static and dynamic shear force loading tests were conducted on a plane incorporating the friction damper. The results showed that the bracket and steel pipe were sufficiently rigid and flexible to fulfill the original damping effect of said friction damper and the loading deformation curve of the total plane clearly indicated sufficient damping properties.

Effect of Annular Incision Type on the Change in Biomechanical Properties in a Herniated Lumbar Intervertebral Disc

The technique used to incise the disc during discectomy may play a role in the subsequent healing and change in biomechanical stiffness of the disc. Several techniques of lumbar disc annulotomy have been described in clinical reports. The purpose of this paper was to study the influence of annulotomy technique on motion segment stiffness using a finite element model. Four incision methods (square, circular, cross, and slit) were compared. The analyses showed that each of the annular incisions produced increase in motions under axial moment loadings with circular incision producing the largest change in the corresponding rotational motion. Under shear loading mode, cross and slit-type annular incisions produced slightly larger changes in the principal motions of the disc than square and circular incisions. All other incision types considered in the current study produced negligibly small increase in motion under rest of the loading conditions. In addition to annulotomy, when nucleotomy was also included in the analyses, once again cross and slit incisions produced larger change in motion under shear loading mode as compared to the other two incision types. A comparison between the four types of annular incisions showed that cross incision produced an increase in motion larger than those produced by the other three incisions under flexion/extension and lateral moment loading and both shear force loadings. Circular incision produced the largest increase in motion under axial moment load in comparison to those produced by square, cross, and slit incisions. Sagittal plane symmetry was influenced by the incision injury to the motion segment leading to coupled motions as well as increased facet loads. From the study it can be concluded that the increase inflexibility of the disc due to annulotomy depends on the type of annulotomy and the annulotomy also produce asymmetrical deformations leading to increased facet loading.

鋼管柱・梁接合部パネルのせん断加力実験

When a steel frame is subjected to horizontal force due to earthquake, high shear force is developed in the beam-to-column joint panel. Many studies to investigate the strength and deformation of joint panel were carried out. In this paper, the shear force loading tests for joint panel and for cruciform subassemblage of rectangular and circular hollow section are reported. As the main experimental parameter of these tests, axial force ratio and loading direction are selected. The results are summarized as follows. The hysteretic characteristics of joint panel are different from the steel grade and how to make of rectangular and circular hollow sections. Axial force leads to reduction of the strength and the increase of axial displacement. The hystereses of joint panel in cruciform subassemblages are similar with those of specimens of shear loading test. And the strength of panels agrees with those of specimens of shear loading test.