A Screening Method for Prevention of Ratcheting Strain Derived From Movement of Temperature Distribution

In this paper, we simplify the existing method and propose a screening method to prevent thermal ratcheting strain in the design of practical components. The proposed method consists of two steps to prevent the continuous accumulation of ratcheting strain. The first step is to determine whether all points through the wall thickness are in the plastic state. This is based on an equivalent membrane stress, which comprises the primary stress and the secondary membrane stress. When the equivalent stress exceeds the yield strength in some regions of the cylinder, the axial lengths of these regions are measured for the second step. The second step is to determine whether the accumulation of the plastic strain saturates. For this purpose, we define the screening criteria for the length of the area with full section yield state. When this length is sufficiently small, residual stress is generated in the direction opposite to the plastic deformation direction. As a result of residual stress, further accumulation of the plastic deformation is suppressed, and finally shakedown occurs. To validate the proposed method, we performed a set of elastoplastic finite element method (FEM) analyses, with the assumption of elastic perfectly plastic material. Not only did we investigate about the effect of the axial length of the area with full section yield state but also we investigated about effects of spatial distribution of temperature, existence of primary stress, and radius thickness ratio.

The Contrastive Analysis of Bending Strength Computing Methods of Concrete Filled Steel Tube Member

Three bending strength computing methods of concrete filled steel tube are introduced, including empirical formula method, whole section yield method and simplify numerical method. There are some difference on their computing results. To verify their difference, single factor analysis method is used. The single factor include the thickness of steel tube, the strength of concrete and the strength of steel. The revised results of ABAQUS are used as a benchmark. The analysis include two aspects, one from the changing trends of ABAQUS’ results and the three method’ results when only one factor is increasing, the other from the magnitude of relative error between the results of ABAQUS and the results of every method. Finally, the scope of every method is obtained.

Investigation on Residual Strength of Airplane Plate with Smooth Circular Hole

In order to solve the fight problem of damaged airplane in war, based on linear elasticity, elastoplasticity and net section yield criterion, the calculation model for residual strength of plate with smooth circular hole is founded. Furthermore, the flexibility of calculation models using these three methods is analyzed through examples. All above can be basis for airplane battle damage assessment.

Experimental Study on Residual Strength of Panels with Multiple Site Damage

The fatigue test of typical bolt-hole panels with five open holes in a line and the residual strength test of the panels with multiple site crack (MSD) were carried out. The crack initiation life of the test panels and the residual strength of the panels with different MSD crack sizes were obtained by the tests. The application of the net section yield criterion in the determination of residual strength of the panel containing multiple site damage was studied by comparing the calculated results with the test results. The conclusion is that the criterion meets the engineering accuracy requirement in the case of smaller MSD cracked area or smaller MSD crack sizes.