Papers by Keyword: Stiffener

Abstract: In current days, sandwich structures have become popular due to their flexibility with design requirements and excellent performance under extreme loads, such as blast. There are different strategies for enhancing the blast resistance of such sandwich structures. Including an additional layer of polyurea and stiffeners are widely used techniques that may enhance the performance of the panels under high-rate loadings. In this study, the effects of polyurea and stiffeners on the protection of a steel and aluminum foam sandwich panels is studied. Effective configuration of the panels with both polyurea and stiffeners are investigated. Here, different configuration cases of the sandwich panels: (a) panel without polyurea and stiffeners, (b) with polyurea applied on the rear face, (c) with stiffeners applied on the rear face, and (d) with stiffeners and polyurea on the rear face are investigated and compared. The finite element models of sandwich panels are developed, where steel facesheets, steel stiffeners, and polyurea are modeled with shell elements, and aluminum foam core is modeled with solid elements. Elastic-plastic, crushing foam, and hyperelastic material behaviors are implemented for steel, aluminum, and polyurea layers of the sandwich panels, respectively. The performance of the different configurations of the panels are compared in terms of the response quantities, i.e., deformation, equivalent von-Mises stresses, and energy absorption. Moreover, the damage patterns with fragmentation effect are depicted for all the considered sandwich panels. The results of the study show that both polyurea and stiffeners are the most effective configurations in protecting the sandwich structures; however, with the same thickness of polyurea and stiffener, the stiffeners show better performance than polyurea against blast load. Furthermore, it is observed that the deflection values across the configurations follow a logarithmic decay pattern.

Abstract: This paper presents a 2.5D moving iso-surface threshold (MIST) approach for findingtopological configurations of stiffeners for stiffened and sandwiched plates subjected to staticbending load. In this 2.5D MIST approach, (a) 3D elements are used to discretize a continuum intomulti-layered finite element model with either one or two surface layers of elements as non-designdomain; (b) the 3D non-surface elements, collocated in the thickness direction, are grouped togetherand used to define one amalgamated physical response function for each series of elements in a 2Ddesign domain; (c) optimum designs on the layout of stiffeners attached to a panel or sandwichedbetween two panels are obtained using MIST from the grouped 3D elements. Several numericalexamples are presented to demonstrate the effectiveness of the proposed approach in designingpractical stiffener topology. By using representative volume element and repetitive boundaryconditions as well as loading combinations, designs of stiffener are obtained for selected stiffenedand sandwiched plates under chosen static loading.

Abstract: In truss-steel plate shear wall (SPSW) structures, the main role of SPSW is to provide horizontal and vertical stiffness for the system, which requires the SPSW capable of adapting to bi-directional loading. In order to satisfy the goal, stiffeners need to be added to the SPSW. In addition, openings are usually set within the SPSWs to meet certain architecture or utilization needs. Stiffener design criteria for such SPSW with or without opening are first derived according to the principle of yielding before buckling and local buckling before overall buckling. Then the deduced stiffener design criteria are compared with the current design codes. Finally the stiffener design recommendations are proposed for SPSW with or without opening adapting to bi-directional loading.

Abstract: We get the load and the work stress of aircraft accessory gearbox shell based on every starting and flying conditions of plane. By analyzing the stress level and stress distribution of the shell ,we assessed the shell structure validity and then proposed improving method .The study shows , the strength of the bearing mounting holes and its supporting stiffeners of the shell is lower than else structure part, and the starting condition is strength weak condition of the shell, so the study results supplies a theory reference to the design and improve method of aircraft accessory gearbox shell structure.

Abstract: Concrete-filled rectangular steel tube four sides restraint effect on the core concrete was weaker than the corner, which made the effect not significant. The paper studied a new kind of stiffening rib –PBL stiffener to strengthen restraint effect of concrete-filled rectangular steel tube , and evaluated its advantages compared with other stiffening ribs. 9 PBL stiffened concrete-filled rectangular steel tube columns under axial compressive load were tested. It also collected the test with other stiffened rids, such as straight ribs, binding bars, knee brace, steel reinforcement cage, steel bar stiffeners, saw tooth shaped stiffeners, stitching straight stiffeners and no rib concrete filled rectangular steel tube to compare. It evaluated increasing coefficient of bearing capacity by stiffening ribs. The results showed that: the PBL stiffeners and binding bar of concrete-filled rectangular steel tube bearing capacity was greater than other reinforcement measures by more than 20%; PBL stiffener could be a new prominent type of stiffener because of its excellent mechanical performance and simple construction.

Abstract: Using nonlinear finite element method, the three dimensional nonlinear analysis of the radial steel gate of a reservoir is carried out. In the analysis, the radial steel gate considering and without considering the stiffeners of the panel is analyzed to investigate the effect of the stiffener to the panel. In the corrosion sensitive analysis, the panel of the gate is divided into three sections, and the nonlinear analysis is carried out for each section that is rusted with different corrosion depth. The corrosion sensitive section and the stress variation with the corrosion depth are present.

Abstract: A noval concrete structure strengthening technique which employs aluminum alloy plate of stiffened sections was presented. Aluminum plate width, stiffener number and height were considered for bond performance investigations. Based on the simlple shear test, three types of failure mode were observed in this study. Test results indicates that the couple effect of aluminum width and stiffener number is more remarkable than stiffener height for strengthening behaviour. A set of comparison over the behaviour of aluminum laminate were carried out among EBR, NSM and stiffened plates. It shows that the siffened plates can be used sucessfully in concrete strengthening.

Abstract: This paper presents an efficient finite element modeling technique for stiffened composite shells having different stiffening arrangements. The laminated shell skin is modeled with a triangular degenerated curved shell element having 3 corner nodes and 3 mid-side nodes. An efficient curved beam element compatible with the shell element is developed for the modeling of stiffeners which may have different lamination schemes. The formulation of the 3 nod degenerated beam element may be considered as one of the major contributions. The deformation of the beam element is completely defined in terms of the degrees of freedom of shell elements and it does not require any additional degrees of freedom. As the usual formulation of degenerated beam elements overestimates their torsional rigidity, a torsion correction factor is introduced for different lamination schemes. Numerical examples are solved by the proposed finite element technique to assess its performance.

Abstract: Abstract: 7 square steel tubular columns were tested to discuss the ultimate axial bearing capacity, ductility performance and the steel consumption under stiffened by steel belts and binding bars of different cross-sections. Test results indicate that only by increasing fewer amounts of steel usage, stiffened square CFST columns with binding bars can not only improve the overall effects of restraint and alleviate regional local buckling between the binding bars, but also improve the bearing capacity of concrete filled square steel tubular columns. The utility benefits and the economical benefit is considerable, deserving extensive use.

Abstract: Stiffing steel plate deep beam is introduced as a new lateral force resistant structure system and put forward mechanism of stiffing steel plate deep beam. Mechanical property of stiffing steel plate deep beam with different span-depth ratio under horizontal low cyclic load is analyzed through ANSYS which is a software of finite element analysis. The results indicates that with decreasing of span-depth ratio ultimate load raised substantially and strength of component gradually changes from depending on bending to shearing. The optimal value of span-depth ratio is 1.5.