Action Of Compressive Loads Research Articles

Numerical Investigation of the Ultimate Load-Carrying Capacity of Square Concrete-Filled Steel Tube Columns Considering Initial Stresses Generated during Construction

During construction, newly cast concrete exerts lateral pressure on the steel plates of concrete-filled steel tube (CFST) columns, resulting in non-negligible initial circumferential stresses. Finite element analysis, in which lateral pressure is applied using a user-defined load subroutine, was conducted to comprehensively investigate the effects of initial stresses, including circumferential stresses, on the structural behaviors of a square CFST column under the action of compressive load. This study also provides guidance for the numerical simulation of CFST columns under complicated construction scenarios. The analysis revealed that the steel tube plates were more sensitive to lateral pressure, which should be limited during construction, compared with gravity loads. Under the action of compressive load, the presence of initial stresses altered the failure modes of the square CFST columns and reduced their ultimate load-carrying capacities (ULCCs). For columns with slenderness ratios of 18 and 37, the ULCCs were essentially inversely proportional to the initial stress ratio β, ranging from 0.1 to 0.5. However, for columns with a larger slenderness ratio of 55, the initial stress level did not influence their ULCCs. Finally, a simple method for calculating the ULCCs of square CFST columns considering initial stresses is proposed for design purposes.

Theoretical analysis of two cracks in sandstone under the simultaneous action of pressure and shear stress

AbstractThe cracked rock mass could slide along the weak side under the action of compressive loads and shear loads in landslides; thus, the stability evaluation of the crack in rock mass media is of particular importance. The formulas of stress intensity factors (SIFs) for each crack tip are theoretically derived by implementing complex function theory. The results of the analytical solutions are then compared with the predicted results of the finite element analysis via ABAQUS software, revealing a slight relative error. Photo elastic experiment and static compression tests are conducted to verify the correctness of theoretical results. The obtained results reveal that the internal pressure leads to the increasing SIFs of mode II at crack tips. Further, the larger the difference between the horizontal and vertical compressive stresses, the more likely the occurrence of shear failure in the cracked rock mass. For the two cracks, the most dangerous point is the inner crack tip of the longer crack.

Buckling Behavior of Poly-Phenylene-Sulfide/Carbon L-Shaped Stringers and a Stiffened Panel Obtained by Induction Welding

Although the high performance thermoplastics matrix composites have been studied for more than thirty years, only recently their advantages have been properly perceived and exploited, for a wide range of applications either in secondary either in primary aeronautical structures. In this work, compression testing of a flat panel stiffened with L-shaped stringers made of Polyphenylene-sulfide (PPS) matrix reinforced with carbon fibres, is presented. The stiffeners were joined to the base plate by induction welding, as reported in a former study. The numerical activities, aimed at static, buckling and post-buckling analysis, first of a single stringer, then of the stiffened panel under compressive load, provided results in good agreement with the experimental ones. The analyses were performed taking into account either for the geometric non-linearity associated with the large deformations of the structures under the action of compressive loads either for the local buckling of the flanges composing the stringers. Experimental activities were aimed at the characterization of the adopted materials with a special focus on the determination of buckling loads either of an L-shaped stringer either of a panel stiffened with four stingers. In both cases an excellent structural behaviour was shown, the panel and a single stringer being able to take huge loads after the first buckling appeared. The panel, in particular, showed an excellent post-buckling strength and broke by buckling failure of stringers. The welded interfaces did not fail indicating that thermoplastic welding is a suitable technique for assembly composite structural elements.

Prediction of Load-Bearing Capacity of Composite Parts with Low-Velocity Impact Damage: Identification of Intra- and Inter-Ply Constitutive Models

Assessments of residual load-carrying capacity are often conducted for composite structural components that have received impact damage. The availability of a verified simulation methodology can provide significant cost savings when such assessments are required. To support the development of a reliable and accurate simulation methodology, this study investigated the predictive capabilities of a stacked solid-shell finite element model of a cylindrical composite component with a damage mechanics-based description of the intra-ply material response and a cohesive contact model used for simulation of the inter-ply behavior. Identification of material properties for the model was conducted through mechanical characterization. Special attention was paid to understanding the influence of non-physical parameters of the intra- and inter-ply material models on predicting compressive failure load of damaged composite cylinders. Calibration of the model conducted using the response surface methodology allowed for identifying rational values of the non-physical parameters. The results of simulations with the identified and calibrated finite element model showed reasonable correlation with experimental data in terms of the predicted failure loads and post-impact and post-failure damage modes. The investigated modeling technique can be recommended for evaluating the residual load-bearing capacity of flat and curved composite parts with impact damage working under the action of compressive loads.

Model of deformation of a feather quill when rolling with a ribbed roller on the flat surface

Mathematical modeling is an effective and cost-effective alternative to a trial physical experiment in solving problems associated with the development of new technologies and equipment. The paper is devoted to modeling the deformation process of a feather quill when rolling by a ribbed roller on a flat surface to form thorough kneading on its concave side, providing additional bending. The technology is used to enhance the Executive ability (“Fill Power” measure) of feather stock of land birds, which are used for manufacturing down-feather products, as an alternative to increasingly scarce and expensive feahers of waterfowl. This is especially true for products with a short service life, intended for use in the rectifying natural disasters and the consequences of accidents.The developed mathematical model allows us to investigate the dependence of the resistance force of the roller on the design parameters of the working body: the knurling pitch; the angular size of the flute; the diameter of the riffle vertices.Stresses arising in the structure of the quill under the action of compressive load, when loading and removing the load in an arbitrary cross-section of a feather quill have different values and are described by the corresponding regression models. The solution of the system of regression equations together with the kinematic equations of motion of the working body allows to determine the strength of resistance and power requirement of the deformation of feather quill of land birds to improve the “Fill Power” of feather stock.The dependence of the total rolling resistance force for the working body and the chicken feather quill of the given parameters obtained on the model is given.

Vibration Analysis for Bending of Vertical Plates in PVC Scrap Filtration Machine

A PVC scrap filtration machine used in VIJAY PLASTIC, Solapur to filter PVC scrap in fine granual by vibrating a bed. The machine vibrates with its leg support i.e. vertical plate which is bend after some instances. This project more focus on static and dynamic analysis of vertical plates of PVC scrap filtration machine. It is necessary to study various loads acting on plates like weight of various components of body, load of PVC scrap which would add to per cycle and the buckling load. Buckling leads to a failure. When a structure is subjected to compressive stress, buckling may occur. It is characterized by a sudden sideways deflection of a structural member. The static load considered for force analysis is not responsible for bending which is calculated and hence it is required to experiment the model for vibration in dynamic body. With the help of ANSYS APDL 19., the stress values of plates due to force acting on plates is obtained and it is found to be safe. There is no any buckling or bending happen in steady condition. There is small deflection after action of compressive load. From static analysis result it can be concluded that buckling of plates occurs due to accelerating condition. So, the next step is dynamic analysis of vertical plate. The project has a great future scope as by investigating the amount of vibration into the system and with the help of dynamic calculation it can be find out the root causes of vibration so that the vibration can be eliminated to maximum extent and thus the life of the system may increase. The future scope of project is to find factors responsible for bending of vertical plate and to modify it as per necessary changes possible with the help of analytical, experimental and finite element analysis technique.

A contact problem for a plane weakened by a periodic system of variable width slots

We consider a problem on compression of an elastic isotropic plane with a periodic system of slots of variable width comparable with elastic deformations. The case of appearance of several contact sections of slot faces contact is studied. Therewith it is considered that on some part of the contact area there arises adhesion of faces, on the remaining part the slippage may happen. The problem on equilibrium of periodical system of slots with partially contacting faces under the action of compressive load is reduced to the problem of linear conjugation of analytic functions. Contact stresses, sizes of contact sections and adhesion zones are determined.

The Mechanism Investigation on Propagation and Coalescence Pattern of Three Internal Plane Flaws in Brittle Materials

Under the action of compressive load, the growth and coalescence containing flaws in brittle materials (rock and rocklike materials e.g.) will result in the local buckling and global fracture of rockmass. But, the mechanisms on propagation and coalescence of 3-dimensional internal flaws are not clear till now. We examine brittle fractures of manmade specimens using frozen casting resin and rocklike material to observe 3D internal flaws growth process at about -30° C. A team of specimens containing three internal flaws is measured; flaws are made of three parallel oblong aluminum films. The propagation and coalescence pattern of three internal flaws is observed under compressive stress. An interesting phenomenon is that the crack initiated from the second flaw quickly turns to the one induced from the third flaw and forms a bigger fracture plane, then splits the specimen. It shows that the flaw distribution pattern will greatly affect the flaws growth and coalescence process. The mechanisms that lead to the wing and anti-wing crack initiation and coalescence are described.

Unusual nonlinear response of some metallic materials

An anomalous material response has been observed under the action of compressive loads in fibrous silicon carbide/titanium (both Ti-6242 and Ti-15-3 alloys) and the nickel-base alloy Inconel 718 in the aged (precipitation hardened) condition. The observed behavior is an increase, rather than a decrease, in the instantaneous Young's modulus with increasing load and is referred to as stiffening. This increase is small, but can be significant in yield surface tests where an equivalent offset strain on the order of 10 με (10 × 10 −6 m/m) is being used. Stiffening has been quantified by calculating offset strains from the linear elastic loading line. The offset strains associated with stiffening during compressive loading are positive and of the same order as the target offset strains in yield surface tests. Stiffening appears to be nonlinear elastic and for SiC/Ti-15-3 decreases as the test temperature increases, suggesting a temperature-dependent mechanism. No stiffening occurred in SiC/Ti-15-3 above approximately 500°C. In addition, the tensile response of aged Inconel 718 exhibits a nonlinear elastic response (not stiffening) prior to the initiation of plastic deformation. The nonlinear elastic response in both tension and compression agrees with a second order stress–strain relation. The higher order terms may be important due to constraint interactions associated with a strengthening second phase such as precipitates or fibers.

Crack development in plane under the action of compressive load

Crack development in plane under the action of compressive load