• Steel and Composite Structures
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• 제36권1호
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• pp.75-86
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• 2020

The grid structures with welded hollow spherical joint (WHSJ) have gained increasing popularity for use in industrial buildings with suspended cranes, and usually welded with steel tube (ST). The fatigue performance of steel tube-welded hollow spherical joint (ST-WHSJ) is however not yet well characterized, and there is little research on fatigue life prediction methods of ST-WHSJ. In this study, based on previous fatigue tests, three series of specimen fatigue data with different design parameters and stress ratios were compared, and two fatigue failure modes were revealed: failure at the weld toe of the ST and the WHSJ respectively. Then, S-N curves of nominal stress were uniformed. Furthermore, a finite element model (FEM) was validated by static test, and was introduced to assess fatigue behavior with the hot spot stress method (HSSM) and the effective notch stress method (ENSM). Both methods could provide conservative predictions, and these two methods had similar results. However, ENSM, especially when using von Mises stress, had a better fit for the series with a non- positive stress ratio. After including the welding residual stress and mean stress, analyses with the local stress method (LSM) and the critical distance method (CDM, including point method and line method) were carried out. It could be seen that the point method of CDM led to more accurate predictions than LSM, and was recommended for series with positive stress ratios.

• 한국자동차공학회논문집
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• 제19권2호
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• pp.111-116
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• 2011

Three-dimensional finite element analyses have been performed to improve the durability of bulkhead. To keep pace with design changes and concentrate on regions of interest, SUBMODEL technique in ABAQUS was used for analysis. An analysis was conducted with following load cases: 1) Cap press-fit, 2) Bearing crush, 3) Bolt assembly, 4) Hot assembly, 5) Firing load, 6) Alternating firing load, 7) 2nd hot assembly. Fatigue analysis was done using commercial software FEMFAT and fatigue factors at the interested regions such as bolt tip area, counter bore, breathing hole, honing clearance were calculated and compared to aid design validation. Finite element modeling in the area of thread engagement used a simple constraint equations. Increasing bolt length, to a minimum of 39 mm above joint face gives a better fatigue resistance to the bulkhead. Breathing hole helps not only circulate the air in the crankcase but also fatigue resistance of bulkhead by relieving the stress at the critical locations.

• Earthquakes and Structures
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• 제8권5호
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• pp.957-976
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• 2015

Recently, two energy-based response parameters, i.e., the absolute and the relative elastic input energy equivalent velocity, have been receiving a lot of research attention. Several studies, in fact, have demonstrated the potential of these intensity measures in the prediction of the seismic structural response. Although some ground motion prediction equations have been developed for these parameters, they only provide marginal distributions without information about the joint occurrence of the spectral values at different periods. In order to build new prediction models for the two equivalent velocities, a large set of ground motion records is used to calculate the correlation coefficients between the response spectral values corresponding to different periods and components of the ground motion. Then, functional forms adopted in models from the literature are calibrated to fit the obtained data. A new functional form is proposed to improve the predictions of the considered models from the literature. The components of the ground motion considered in this study are the two horizontal ones only. Potential uses of the proposed equations in addition to the prediction of the correlation coefficients of the equivalent velocity spectral values are shown, such as the prediction of derived intensity measures and the development of conditional mean spectra.

• Steel and Composite Structures
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• 제17권3호
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• pp.237-252
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• 2014

The use of composite structures is increasingly present in civil building works. Composite Box Girder Bridges (CBGB), particularly, are study of effect of shear connector's numbers and distribution on the behavior of CBGBs is submitted. A Predicti structures consisting of two materials, both connected by metal devices known as shear connectors. The main functions of these connectors are to allow for the joint behavior of the girder-deck, to restrict longitudinal slipping and uplifting at the element's interface and to take shear forces. This paper presents 3D numerical models of CBGBs to simulate their actual structural behavior, with emphasis on the girder-deck interface. Additionally, a Prediction of several FE models is assessed against the results acquired from a field test. A number of factors are considered, and confirmed through experiments, especially full shear connections, which are obviously essential in composite box girder. A good representation for shear connectors by suitable element type is considered. Numerical predictions of vertical displacements at critical sections fit fairly well with those evaluated experimentally. The agreement between the FE models and the experimental models show that the FE model can aid engineers in design practices of box girder bridges. Preliminary results indicate that number of shear studs can be significantly reduced to facilitate adoption of a new arrangement in modeling CBGBs with full composition. However, a further feasibility study to investigate the practical and economic aspects of such a remedy is recommended, and it may represent partial composition in such modeling.

• Advances in Computational Design
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• 제8권2호
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• pp.97-112
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• 2023

The Finite Element (FE) modeling of Reinforced Concrete (RC) under seismic loading has a sensitive impact in terms of getting good contribution compared to experimental results. Several idealized model types for simulating the nonlinear response have been developed based on the plasticity distribution alone the model. The Continuum Models are the most used category of modeling, to understand the seismic behavior of structural elements in terms of their components, cracking patterns, hysteretic response, and failure mechanisms. However, the material modeling, contact and nonlinear analysis strategy are highly complex due to the joint operation of concrete and steel. This paper presents a numerical simulation of a chosen RC column under monotonic and cyclic loading using the FE Abaqus, to assessthe hysteretic response and failure mechanisms in the RC columns, where the perfect bonding option is used for the contact between concrete and steel. While results of the numerical study under cyclic loading compared to experimental tests might be unsuccessful due to the lack of bond-slip modeling. The monotonic loading shows a good estimation of the envelope response and deformation components. In addition, this work further demonstrates the advantage and efficiency of the damage distributions since the obtained damage distributions fit the expected results.

• Smart Structures and Systems
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• 제17권5호
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• pp.819-835
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• 2016

In this paper, the activities carried out within the EU funded Clean Sky Joint Technology Initiative (JTI GRA) Project and aimed at developing a morphing flap, are illustrated. The reference device is a regional aircraft single slotted flap, enhanced with deforming capabilities to obtain improved hyper-lift performance. The design started with the identification of the internal architecture, intended to allow camber variations. A concentrated-hinge architecture was selected, for its ability to fit different curvatures and for the possibility of easily realizing an "armadillo-like" configuration, then avoiding the use of a complicate deformable skin. The flap layout is made of segmented ribs, elastically hinged each other and span-wise connected by conventional spars. Relative rotations of the rib elements are forced by SMA structural actuators, i.e., cooperating in the external loads absorption. Super-elastic SMA are used to make up recovery elastic elements, necessary to regain the original shape after activation. These further elements in turn contribute to the overall flap rigidity. After assessing the hinge number and the size of the SMA active and passive elements, the advanced design phase was dealt with. It was aimed at solving manufacturing issues and producing the executive drawings. The realized demonstrator was finally tested in lab conditions to prove its functionality in terms of whether target shape actuation or attained shape preservation under loads. On the basis of the numerical results and the experimental outcomes, precious hints were obtained for further developments of the concept.

• Clinics in Shoulder and Elbow
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• 제14권1호
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• pp.140-145
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• 2011

목적: 금속 요골두 치환술은 주관절 불안정성을 동반한 고정할 수 없는 분쇄된 요골두 골절의 치료로 최근 다양한 임플란트의 개발로 널리 사용되고 있다. 저자는 금속성 요골두 치환술의 적응증과 국내에 사용중인 임플란트의 종류와 수술 술기를 문헌 고찰과 함께 기술하고자 한다. 대상 및 방법: 요골두 치환술의 주 적응증은 동반된 연부조직 손상으로 인한 주관절의 불안정성이 있고, 요골두의 분쇄 골절로 안정적인 내고정이 불가능한 골절이다. 이러한 경우 과거 시행되었던 요골두 절제술은 많은 합병증의 발생으로 금기시되고 있다. 현재 국내에서는 양극성, 압박 고정 단극성 및 이완 고정 단극성 임플란트의 3종류가 수입되어 사용되고 있다. 요골두 치환술은 궁극적으로 원래의 요골두의 크기와 길이로 복원하는 것이 중요하다. 과도하게 긴 요골두의 삽입은 흔한 합병증으로 수술 시 주의가 필요하다. 결과 및 결론: 요골두 치환술은 적절한 적응증과 정확한 수술 술기로 만족할 만한 임상적 결과를 얻을 수 있다. 향후 장기추시 연구와 다양한 치환물들의 임상적인 비교 연구가 필요하다.

• 한국임상수의학회지
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• 제36권1호
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• pp.53-61
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• 2019

Total hip arthroplasty (THA) is a successful surgical treatment for both patients with chronical lameness and dogs who are nonresponsive to medical treatments, providing excellent joint function for returning dogs to the normal gait in 80% to 98% of hip dysplasia (HD) patients. The THA surgical implant system manufactured by BioMedtrix and Kyon are today widely accepted. When comparing the BioMedtrix biological fixation (BFX) system to the BioMedtrix cemented fixation (CFX) system, the many advantages of BFX, which include longer potential implant life, decreased risk of postoperative or later infection, and better implant stability, become evident. However, BFX implies a greater risk of femoral fracture during reaming and requires a more precise surgical technique to achieve good implant fit, given the press-fit nature of cementless THA. The purposes of this study are to both describe the mistakes and complications during stem implantation for beginner surgeons with both the BFX and the CFX systems and to document the initial result of 12 implantations in canine cadavers. Given the detailed evaluations of 3 specialists, who are Diplomate American College of Veterinary Surgeons (DACVS), only 3 of 11 stems were appropriately sized. Specifically, 6 stems were anteverted rather than being retroverted; further, although 7 stems were coaxial with the femoral long axis in the frontal plane, the other stems were in the varus at the frontal plane, with the proximal medial stem adjacent to the medial femoral cortex. Moderate angulation from the cranial to the caudal directions was found in 4 cases in the sagittal plane. Additionally, 1 case of femoral fissure and 1 case of perforated femoral cortex were reported. It is not easy for surgeons performing cementless THA for the first time to achieve a good result, even though they completed an educational course about it and given that catastrophic complications often occurred during early surgical clinical cases. Therefore, ex-vivo studies are sincerely required to get an expertise by rehearsing the preparation of the femoral envelop in isolated bones. Further studies should be conducted to achieve both highly accurate implant size and correct orientation during the preoperative planning. Additionally, surgeons' learning curve should be examined in future investigations.