Axial Load Capability Research Articles

Experimental Investigation of the Axial Behaviour for Battened Tubular Columns

This paper describes a series of experiments on batten tubular specimens with various slenderness ratios. The experimental study was employed to satisfy the expectations of behaviour and axial load capability of battened tubular columns. Twelve specimens composed of four tubes having different global column slenderness and various ratios of the unbraced chord slenderness-to-the global column slenderness were chosen to cover stub, short and medium columns. The tubes were assembled with welded batten plates. A numerical model with a thin shell element considered both geometric and material nonlinearities was used to verify the experimental results. Tests result showed different failure modes, such as local, local-flexural and flexural buckling. By comparing, the finite element and tested results have a good agreement. The results revealed the strength of the battened columns, which was related to the effect of global slenderness and spacers on the buckling behaviour. Additionally, the stub, short and medium column strengths were enhanced by 8%, 25%, and 78%; respectively, when the number of spacers increased to four batten plates. Eventually, predicted strengths of the battened column by AISC and EC3 specifications were slightly un-conservative.

Permodelan Pengekangan Kolom Pada Beton Mutu Normal Dengan Metode Elemen Hingga 3-D

The column is a critical element in the building structure, the failure of the column will directly result in the collapse of other related structural components. The column must have strength, stability and ductility. In increasing the capacity and ductility of the column by providing confinement, to protect concrete elements from breaking due to the influence of the working pressure. Analyzing ultimate axial load capability, stress-strain distribution patterns and crack patterns in concrete elements and column ductility. Tests of several models and variations of the restraint distance in short columns of normal concrete quality with longitudinal reinforcement of steel steels and carbon steel transversal reinforcement. The columns were analyzed using the Finite Element Analysis (FEA) method with the help of a full scale ANSYS 3-D application, with material properties for concrete using SOLID65 and steel reinforcement using LINK8 and SOLID45 loading plates. The type of pedestal used is the joints with axial loading (axial loadstep) centric direction. The effect of the restraint model and the variation of the restraint distance to the value of the column ultimate axial load for the whole model is relatively small with a ratio of 1.079, while for the ratio of the axial deformation ratio of 1.496. The pattern of stress and strain distribution when yielding spreads throughout the column area but when it reaches the ultimate distribution the concentration is concentrated in the support area. The first dominant crack occurs in the pedestal area and generally occurs in the concrete blanket layer, in the ultimate condition cracks have occurred evenly throughout the column area. The ratio of the ratio of ductility values ??for all column models and the restraint distance is relatively large with a ratio value of 1.523

Stent screw-assisted internal fixation (SAIF): clinical report of a novel approach to stabilizing and internally fixating vertebrae destroyed by malignancy.

Severe lytic cancerous lesions of the spine are associated with significant morbidity and treatment challenges. Stabilization and restoration of the axial load capability of the vertebral body (VB) are important to prevent or arrest vertebral collapse. Percutaneous stent screw-assisted internal fixation (SAIF), which anchors a VB stent/cement complex with pedicular screws to the posterior vertebral elements, is a minimally invasive, image-guided, 360° internal fixation technique that can be utilized in this patient cohort. The purpose of this study was to assess the feasibility, safety, and stabilization efficacy of VB reconstruction via the SAIF technique in a cohort of patients with extensive lytic vertebral lesions, who were considered to have an unstable or potentially unstable spine according to the Spinal Instability Neoplastic Score (SINS). This study was a retrospective assessment of a prospectively maintained database of a consecutive series of patients with neoplastic extensive extracompartmental osteolysis (Tomita type 4-6) of the VB treated with the SAIF technique. VB reconstruction was assessed on postprocedure plain radiographs and CT by two independent raters. Technical and clinical complications were recorded. Clinical and imaging follow-ups were assessed. Thirty-five patients with extensive osteolytic metastatic lesions of the VB underwent 36 SAIF procedures. SAIF was performed as a stand-alone procedure in 31/36 cases and was associated with posterior surgical fixation in 5/36 (4/5 with decompressive laminectomy). In 1 case an epidural cement leak required surgical decompression. VB reconstruction was categorized as satisfactory (excellent or good rating) by the two raters in 34/36 cases (94.5%) with an interrater reliability of 94.4% (Cohen's kappa of 0.8). Follow-up, ranging from 1 to 30 months, was available for 30/36 levels. Long-term follow-up (6-30 months, mean 11.5 months) was available for 16/36 levels. Stability during follow-up was noted in 29/30 cases. SAIF provides 360° nonfusion internal fixation that stabilizes the VB in patients with extensive lytic lesions that would otherwise be challenging to treat.

Stent-screw-assisted internal fixation: the SAIF technique to augment severe osteoporotic and neoplastic vertebral body fractures

ObjectivesTo describe a new technique to obtain minimally invasive but efficient vertebral body (VB) reconstruction, augmentation, and stabilization in severe osteoporotic and neoplastic fractures, combining two pre-existing procedures. The implant...

Finite element analysis of the clamp band joint

In this paper, the clamp band joint commonly used to connect cylindrical shells with end flanges is modeled using the finite element analysis software ANSYS. The joint model is validated by a series of static experiments. Then the response of the joint components to the preload and the axial load is analyzed in detail, from which the axial load capability, the axial stiffness and the damping characteristics of the clamp band joint are discussed. Finally, parametric studies are carried out to investigate the effects of the preload, the wedge angle, the friction coefficient, and the number and size of the V-segment on the behavior of the clamp band joint. This paper presents the general mechanical behavior of the clamp band joint subjected to axial loads.

Optimal design of thrust bearing for high-speed composite air spindles

High-speed air spindles are appropriate for high-speed and high-precision machining such as small hole drilling of printed circuit board (PCB) or wafer cutting for manufacturing semiconductors. The axial load capability and stiffness of the air spindles for drilling operation are dependent on the thrust bearings. The thrust bearings are composed of an air supply part in the housing and a rotating part. Since stresses induced in the rotating part of thrust bearing by centrifugal force are very high at high-rotational speed, the axial stiffness and load capability of an air spindle should be designed considering stresses due to centrifugal force as well as the natural frequency of the rotating shaft to avoid the resonant whip vibration of the spindle. In this work, the air supply part and the rotating part of a thin thrust bearing were designed for a high-speed carbon fibre composite air spindle using the stiffness map to maximize the stiffness of the thrust bearing under axial and centrifugal forces.

Thrust bearing design for high-speed composite air spindles

The air spindles whose shafts are made of carbon fiber composite are appropriate for high-speed and high-precision machining such as small hole drilling of printed circuit board (PCB) or wafer cutting for manufacturing semiconductors because the carbon fiber composite shaft has low rotational inertia, high damping ratio and high fundamental natural frequency. The axial load capability and stiffness of air spindles for drilling operation are dependent on thrust bearings that are composed of air supply part mounted on the housing and rotating part mounted on the rotating shaft of spindle. Since the stresses induced in the rotating part of thrust bearing by centrifugal force are very high at high-speed rotation, the axial stiffness and load capability of an air spindle should be designed considering the stresses induced by the centrifugal force as well as the natural frequency of rotating shaft to avoid the resonant whip vibration of the spindle. In this work, the air supply part of a thrust air bearing for a high-speed composite air spindle was designed considering its axial stiffness and load capability. The rotating part of the thin thrust bearing was designed through finite element analysis considering the static and dynamic characteristics under axial load and the centrifugal force during high-speed rotation.

Noninvasive determination of ulnar stiffness from mechanical response--in vivo comparison of stiffness and bone mineral content in humans.

An approach referred to as Mechanical Response Tissue Analysis (MRTA) has been developed for the noninvasive determination of mechanical properties of the constituents of the intact limb. Of specific interest in the present study is the bending stiffness of the ulna. The point mechanical impedance properties in the low frequency regime, between 60 and 1,600 Hz are used. The procedure requires a proper design of the probe for good contact of the skin at midshaft and proper support of the proximal and distal ends of the forearm to obtain an approximation to "simple support" of the ulna. A seven-parameter model for the mechanical response is then valid, which includes the first mode of anterior-posterior beam bending of the ulna, the damping and spring effect of the soft tissue between probe and bone, and the damping of musculature. A dynamic analyzer (HP3562A) provides in seconds the impedance curve and the pole-zero curve fit. The physical parameters are obtained from a closed-form solution in terms of the curve-fit parameters. The procedure is automated and is robust and analytically reliable at about the five percent level. Some 80 human subjects have been evaluated by this mechanical response system and by the Norland single photon absorptiometer, providing for the first time in vivo, a comparison of elastic bending stiffness (ulna) and bone mineral content (radius). Three functional parameters of potential clinical value are the cross-sectional bending stiffness EI, the axial load capability Pcr (Euler buckling load) and the bone "sufficiency" S, defined as the ratio of Pcr to body weight. The correlation between EI and bone mineral (r = 0.81) is only slightly less than previous in vitro results with both measurements on the same bone (r = 0.89). When sufficiency is taken into consideration, the correlation of Pcr and bone mineral content is improved (r = 0.89). An implication is that "quality" of bone is a factor which is not indicated by bone mineral content but which is indicated by stiffness. Bone mineral is necessary for proper stiffness but not sufficient. Therefore mechanical measurement should provide a new dimension to be used toward a better understanding of the factors related to bone health and disease.

Aim Investigation of the Axial Load Carrying Capacity of Cylindrical Roller Bearings

Normally cylindrical roller bearings are employed to transmit purely radial loads. However, depending upon the configuration of lips or flanges on the rings, it is sometimes possible to carry an axial load. In certain applications, an axial load capability is essential. A significant feature in determining the performance of a cylindrical roller bearing under axial loading is the lubrication conditions existing between the lips and rolling elements. The paper describes a study of such conditions. The long-term aim of the work is to provide a basis for the design of cylindrical roller bearings to carry axial loads.

Aim Investigation of the Axial Load Carrying Capacity of Cylindrical Roller Bearings

Normally cylindrical roller bearings are employed to transmit purely radial loads. However, depending upon the configuration of lips or flanges on the rings, it is sometimes possible to carry an axial load. In certain applications, an axial load capability is essential. A significant feature in determining the performance of a cylindrical roller bearing under axial loading is the lubrication conditions existing between the lips and rolling elements. The paper describes a study of such conditions. The long-term aim of the work is to provide a basis for the design of cylindrical roller bearings to carry axial loads.