Reliability design of bolt fatigue strength of hollow axle in cylinder of ball grinder
As to the connecting bolt of hollow axle in cylinder of ball grinder, its failure and stress distribution was analyzed, and its load distribution was calculated. As a result, the calculation method of reliable degree of fatigue strength was obtained. It is proved by an example that the method is reliable and has applying value.
Bolt-plate contact assemblies with prestress and external loads: Solved with super element technique
In dynamically loaded bolted assemblies fatigue is the designing factor. The primary quantity that controls the fatigue is the part of the external load that is transferred to the bolt, as described by the ratio between transferred load to external load. In an idealized setting this ratio can be expressed by a stiffness ratio between the plate members and the bolt. The ratio of transferred load is, however, highly dependent on the size and position of the external loading. The bolt-plate/member connection is modelled using the finite element technique. The modelling includes contact between bolt and members and between the clamped member plates. The modelling includes the prestress that is described by a single scalar value. This prestressed state is followed by an arbitrary external load case. In this paper a finite element technique with super elements is applied to solve the contact problem of the combined prestress and external load in an overall non-iterative way. The conclusions are that it is difficult to make general design rules but in most cases the standard calculation methods will underestimate the strength of the connections. However for some specific loading situations this might not be the case.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.