Modular hemipelvic endoprosthesis with a sacral hook: a finite element study

Background A novel hemipelvic endoprosthesis with a sacral hook was introduced previously, and its clinical outcome with midterm follow-up showed decreased prosthesis-related complications, especially decreased rate of aseptic loosening. The aim of present study was to evaluate the role of a sacral hook in prosthesis stability and the biomechanical properties of this hemipelvic endoprosthesis. Methods A three-dimensional model of the postoperative pelvis was developed using computed tomography (CT) images. A force of 500 N was applied, and the distribution of stress and displacement was evaluated. Comparisons were performed to explore the role of the sacral hook in prosthesis stability. Prosthesis improvement was simulated to reduce unexpected breakage of the pubic connection plate. Results In the reconstructed hemipelvis, stress distributions were concentrated on the superior area of the acetabulum, sacral connection component, and sacral hook. A maximum stress of 250 MPa was observed at the root of the sacral connection component. The sacral hook reduced the maximum stress and displacement by 14.1% and 32.5%, respectively, when the prosthesis was well fixed and by 10.0% and 42.1%, respectively, when aseptic loosening occurred. Increasing the thickness of the pubic connection plate from 2 to 3.5 mm reduced the maximum stress by 32.0% and 15.8%, respectively. Conclusion A hemipelvic endoprosthesis with a sacral hook fulfills the biomechanical demands of the hemipelvis and is safe under static conditions. The sacral hook is important for prosthesis stability. Increasing the thickness of the pubic connection plate can reduce the maximum stress and risk of fatigue breakage.

Dynamic behavior of an innovative replaceable pier structure under lateral impact loadings

<p>In order to improve the repair efficiency of bridge piers subjected to vehicle and ship collisions, an innovative replaceable pier structure based on flange connection and PBL shear connector was proposed. The finite element model of the replaceable pier and the traditional pier were developed and then validated through experimental test results. The behavior of replaceable pier and connection joint under lateral impact loading was studied based on numerical simulations. Compared with the traditional pier, it shows that the ability of new replaceable pier to resist impact loading is more favorable, and the connection component of new replaceable pier is repeatable.</p>

Steel hybrid onshore wind towers installed with minimal effort: Development of lifting process

The total costs per produced kilowatt-hour for wind turbines depend significantly on the investment costs. Thereby, the tower is a relevant cost component, which depends on the chosen supporting structure, the material, and especially on the erection process. Here, an innovative erection process is presented in order to minimize the wind turbine installation, which leads to excluding the extra tall cranes for installing the wind turbines with hub heights over 180 m. In order to propose the innovative erection process, a new hybrid lattice/tubular supporting structure for the onshore wind turbines is designed. The connection component between the tubular part and lattice structure is proposed considering the support functionality for the new erection process. Furthermore, the building steps of the complete erection process are explained. The operational and the lifting loads on wind turbine supporting structure are estimated, and consequently, the erection process stages were analyzed. Finally, the finite element simulation are performed to specify the critical stresses in subcomponents of the supporting structure in each lifting stage and to show the feasibility of the erection process. Moreover, the most critical points and the stages are investigated and stress level in the supporting structure components is computed.

Development of a General Component-Based Connection Element for Structural Fire Engineering Analysis

This paper reports on the development of a general-purpose Eurocode-compliant component-based connection finite element for steel-to-steel joints in fire. The development begins by utilising the temperature-dependent connection component characteristics previously developed at the University of Sheffield to create a component-based connection finite element to model flush endplate connections. Subsequently the element was extended to a new connection type with high ductility, the reverse channel. The component models have been developed for the reverse channel under tension and compression. The element has been incorporated into the nonlinear global structural analysis program Vulcan, in which it has been used along with a static-dynamic formulation. The use of the element is illustrated by modelling a fire test at the University of Manchester in which reverse channel connections were used.

Numerical Study on the Static Response of Grouting-Sleeve Reinforcement-Connection Component with Different Sleeve-Rib Space

According to the actual structure, the ABAQUS finite element models of grouting-sleeve reinforcement-connection component with different sleeve-rib space were established, and the mechanical performance of component under the action of axial tension load was studied. Meanwhile, the stress distributions among sleeve with six kinds of sleeve-rib space by means of stress nephogram were obtained. Numerical simulation result shows that with the sleeve-rib space decreasing from 56mm to 8mm, the constraint capability of grouting material on reinforcement is better and better, and the internal force distribution in sleeve tends to be more homogeneous.

Numerical Study on the Influence of Sleeve-Rib Space on the Static Response of Grouting-Sleeve Reinforcement-Connection Component

According to the actual structure of grouting sleeve, the ABAQUS finite element model of grouting-sleeve reinforcement-connection component was established. By changing sleeve-rib space, the influence of sleeve-rib space on the stress and the displacement distribution at grouting material were gotten. Numerical simulation shows that with the decrease of sleeve-rib space, the internal force distribution of grouting material tends to be uniform. Under axial tension load, with the sleeve-rib space of 14mm, the maximum stress of grouting material is lower than its strength, which makes grouting-sleeve reinforcement-connection component to be in a stable work condition.