Effects Of Structural Stiffness Research Articles

Experimental and Numerical Analysis on the Impact Wear Behavior of TP316H Steel.

In this work, the contact force model and experiment methods were used to study the dynamic response and impact wear behavior of TP316H steel. The Flore model and the classic Hertz model were selected for comparison with the experimental results, and the model was revised according to the section parameters of the TP316H tube. The results show that there is a large difference between the models without considering the effect of structural stiffness on the impact system and the test results, whereas the revised model has a good agreement. With the rise in impact mass, the coefficient of restitution increases from 0.65 to 0.78, whereas the energy dissipation and wear volume decrease. Spalling, delamination, plastic deformation, and oxidative wear are the main impact wear mechanism of TP316H steel.

Earthquake Response Spectra Analysis of Bridges considering Pounding at Bilateral Beam Ends Based on an Improved Precise Pounding Algorithm

Asynchronous vibration was generated between the main bridge and approach spans or abutments due to differences in stiffness and mass during an earthquake, thus further leading to pounding at the bilateral beam ends. By taking a T-shaped rigid frame bridge as an example, the bilateral pounding model was abstracted, and the earthquake response spectra considering pounding at the bilateral beam ends were studied, including the maximum displacement spectrum, the acceleration dynamic coefficient spectrum, the pounding force response spectrum, and the response spectrum for the number of pounding events. An improved precise pounding algorithm was proposed to solve the dynamic equation of the bilateral pounding model. This algorithm is based on the precise integration method for solving the second-order dynamic differential equation and reduces the order thereof by introducing a new velocity vector and uses the series method to find the nonhomogeneous term. The system matrix is simpler, and the inversion of the system matrix can be avoided. On this basis, a multipoint earthquake-induced pounding response spectrum program was developed. A total of 18 seismic waves from Class II sites were selected, and the response spectra of 18 waves were analyzed using this new program. Furthermore, the effects of structural stiffness, mass, stiffness of contact element, pounding recovery coefficient, and peak ground acceleration (PGA) on the earthquake response spectrum were studied. Through the analysis of earthquake response spectra and a parametric study, the phenomenon of earthquake-induced pounding of bridges was clarified to the benefit of the analysis and engineering control of earthquake-induced pounding of bridges.

Quantitative analysis for effects of structural stiffness on vibration characteristics of machine tool feed system

The vibration of the feed system remains a long-standing challenge in a machine. Toward this objective, the effects of bearing stiffness, nut rigidity, coupling stiffness, screw length, screw speed and radial stiffness of worktable on the torsional vibration and axial vibration of the table are explored. In this paper, a mathematical model of multi-degree-of-freedom coupling torsional and axial vibration considering various factors is established by the second Lagrange equation, and simulation analysis and experimental verification are carried out. The effects of the variable lead and variable torsional stiffness of the nut on the torsional vibration of the workbench are analyzed. Results show that nut stiffness is the main factor affecting the vibration of the workbench. As the workbench mass, motor speed, screw length and lead increase, the axial vibration of the workbench increases. In the case of lead change, as the axial stiffness of the nut increases, the effect on the torsional vibration of the workbench is reduced. Under the variable torsional stiffness of the nut, with the increase of the lead, the influence of the lead on the torsional vibration of the workbench will increase. The experimental results provide a reference for further research and provide a theoretical basis for vibration reduction and structural optimization.

Effect of structural stiffness on impact-sliding wear behavior of aluminium alloy

Impact-sliding wear is a typical form of composite wear and occurs in many industrial equipment. The effects of structural stiffness on the impact-sliding wear damage and mechanisms of aluminum alloy were investigated using a bespoke impact-sliding device. The damage evolution and mechanisms of the impact-sliding wear for three different structural stiffness conditions were analyzed. Results showed that the main damage zone gradually shifted along the sliding direction with the increase in the structural stiffness. The wear damage of the material was higher for the low and high structural stiffness conditions and resulted in a very rough surface. However, for the medium structural stiffness, the impact-sliding wear exhibited a slow and linear increase and relatively smooth wear scars were observed. Moreover, the main wear mechanism transformed from delamination to ploughing as the structural stiffness increased.

MODELING OF LATERALLY SUPPORTED EMBEDDED STRUCTURES

At lateral load-displacement response of embedded structures, the subgrade reaction method is most extensively used because the nonlinearity of soil and variation of subgrade reaction with depth can be considered relatively easily. In this method, the laterally loaded embedded structure is idealized as a beam on an elastic foundation loaded transversely and restrained by independent elastic springs acting along the length of the beam. The actual subgrade reaction distribution and the structure displacements are not dependent only on the soil stiffness but are rather a result of the mutual relationship between the structural element stiffness and the soil stiffness. A simplified distribution of springs and its stiffness coefficients is presented in this study. Through decoupling the embedded structure deformations into rigid body movement and bending deformation, the subgrade reaction modulus is estimated depending on experimental data of rigid wall movement and its accompanier ultimate passive earth pressure from literatures. The produced structural analysis results using the developed model are in a good agreement comparing with the analytical and numerical results. In addition, a parametric study is carried out, which shows that the effect of structure stiffness is more significant than the soil stiffness and with regarding the economical design is fulfilled by using flexible structural elements than the rigid one when the displacement limits is regarded.

Comparison of potential injuries to the head and lower extremities of a motorcyclist during impact with W-beam and wire rope barriers using FE simulations

ABSTRACTBecause of their lack of protection, motorcyclists are at a higher risk of injury during a crash compared to car occupants and contribute significantly to the road trauma around the world. Roadside barriers are constructed to protect riders from crashes with off-road objects. Among the different types of roadside barriers, the most common is W-beam barriers, which are designed in consideration of the safety of car occupants. Wire rope barriers may be installed as an alternative and have been found to be safe for cars. However, no in-depth investigation of injuries sustained by motorcyclists crashing into these barriers has been reported. The present study aims to investigate and compare potential injuries to a motorcyclist's head and lower extremities during collisions with W-beam and wire rope barriers. To capture the effect of structural stiffness, detailed finite-element (FE) models of the rider (dummy), the motorcycle, and the barriers were used in simulations carried out in LS-Dyna®, an explicit FE solver. The wire rope barrier was found to be capable of restraining the rider on the road in all cases. Although injuries to lower extremities increased in some cases, potentially fatal injuries to the rider's head were reduced by the wire rope barrier.

Effect of Structural Stiffness on the Microvibration Response of the Working Platform of a Microelectronic Plant

Microvibration is one of the key factors affecting the normal operation of a microelectronic plant. Such measures as to increase the stiffness or damping ratio to prevent microvibration are easy to implement and low in cost. By using the finite element analysis software Sap2000 to simulate the microvibration performance of the working platform of a typical microelectronic plant, this paper compared some of its microvibration response when there were shear walls with that when there were no shear walls, discussed efficiency of structural stiffness on its microvibration response. The results indicate through the provision of shear walls to increase the stiffness of working platform enlarge acceleration and velocity response of the structure, it can decrease displacement effect.

A theoretical investigation of the effect of structural stiffness in underwater shock wave loading using the plane wave approximation

A theoretical investigation of the effect of structural stiffness in underwater shock wave loading using the plane wave approximation

Rational Analysis of Raft Foundation

An analysis of a raft foundation is developed which takes into account the interaction of the three elements of the system, i.e., the structure, the raft, and the supporting soil. The stiffness of the structure is incorporated into the stiffness matrix of the raft which is treated as a thin elastic plate supported on a soil mass modeled either by the Wrinkler (spring) or by the linear elastic model. A three-bay by three-bay multistory space frame supported on a square raft is analyzed and the effects of structural stiffness, relative raft-soil stiffness, and soil stiffness are considered in detail for both the Winkler and linear elastic soil models. It is shown that use of the linear elastic model leads to the conclusion that the settlement profile of a flexible raft is concave, thus there is a transfer of load to the outer columns compared with a rigid raft. In contrast, the Winkler analysis predicts a convex settlement profile. Special methods of analysis are developed for rigid structures and for highly flexible rafts.