Abstract: An approximate analytical method is presented to analyze reliability for the structure
with fuzzy-random uncertainty in basic variables. On the basis of equivalent transformation from
fuzzy possibility distribution (FPD) to random probability distribution (RPD), this contribution
expands first order and second moment method (FOSM) for random reliability to that for
fuzzy-random reliability. The expanded FOSM is illustrated by the way of the fuzzy-random low
fatigue life reliability analysis about an aeronautical engine disk affected by fuzzy-random
uncertainty. Comparison between the FOSM and the numerical simulation for the fuzzy-random
reliability demonstrates the precision of the presented computational model.
Abstract: Fatigue strength of duplex stainless steel welded joints with longitudinal fillet welded
guess and with longitudinal flat side guess welded on plate was evaluated by hot spot stress, hot
spot stress S-N curves were produced and compared with normal stress S-N curves. The results
show that the hot spot stress fatigue strength of the two kinds welded joints should be expressed by
only single S-N curve while nominal stress S-N curves can only be regressed respectively. The test
data are greatly above the S-N curves with slope m=3, recommended by IIW, which indicates that
the slope m=3(IIW) has great safety factor in practical engineering application. But there is no
appreciable difference in fatigue strength between duplex stainless steel and common structural
steel with similar welded joints when fixed the test data to slope m=3.
Abstract: The optimization design problem of vibration isolation and shock resistance system is
studied in consideration of acoustical concealment performance and life-force of ships. The
weakness of design method based on continuity is pointed out and combination optimal design
method is brought forward. Then the limiting performance of shock isolation system is analyzed
and two realization methods are discussed. One method is to adopt linear stiffness component with
large damping. The other method is to use multiple linear stiffness components without damping.
Simulation results showed that the optimal loss factor is still 0.4 when the stiffness of shock bumper
is much larger than that of vibration isolator, just the same with that suffering from only shock
loads. Simulation results also showed that limiting performance can be achieved by configuration
optimal design using multiple linear components. The two discussed methods can be used to direct
Abstract: For accurate determination of the service life we must take into account the loading, which
are in most cases random loading of variable amplitude, the geometry and material properties of
construction elements which are known not to be constants. The more precise these input parameters
are modeled; the more precise and reliable are the results.
In our paper we will deal in detail with the model of crack initiation and propagation in the
complex structures as a basis of the algorithm for calculating the service life. For determination of
the service life for the area of short cracks we used Bilby, Cottrell and Swinden model which is
based on the theory of continuously distributed dislocations and we complemented it with random
generation of structure of material before cracks. For the long crack we have developed a stochastic
model for determination of service life.
Abstract: This paper presents a control and diagnostics model of single stage gear wheels using
acoustic responses. The model is based on various methods and procedures that provide information
about the generator’s condition and, specifically, its service life. Four procedures are combined in
this model: the mathematical module of the gear wheel that translates the complete mechanical
module into mathematical form, the adaptive FIR (Finite Impulse Response) filter that calculates
impulse responses from the non-linear system, the module for calculating any impulse response,
and the FFT (Fast Fourier Transform) frequency analysis used for simulating frequency spectrums.
The result of the simulation is the sound frequency spectrum that allows the analysis of gear wheel
tooth damage and, based on this spectrum, calculation of the remaining service life and/or the
Abstract: The strengthening of concrete structures in situ with externally bonded carbon fiber is
increasingly being used for repair and rehabilitation of existing structures since carbon fiber has good
mechanical properties such as high tensile strength, good resistances to corrosion, and low self-weight,
which are attractive for retrofitting of RC member. In using Carbon Fiber Mesh (CFM) as a retrofit
material for RC member, most important structural property that should be developed is the bond
strength between RC member and CFM. The additional strength increment by CFM can be developed
if the bond strength is sufficient. If it is not, the strengthening effect can not be expected due to the
bond failure between concrete and CFM.
A direct tensile test was performed in order to find the variation of bond strength and
load-displacement response of CFM attached to the concrete and the result is presented in this paper.
The key parameters of the test are the location of clip for the installation of CFM, number of clips and
thickness of cover mortar. Test results indicate that the bond strength is dependent on the number of
clips and maximized at clip numbers of three per each rod. In specimens without clips, the highest
strength was found in the specimen with cove mortar of 30mm and lowest one in specimen with largest
mortar thickness. This means that in too much thick of cover mortar, it seems that the amount of drying
shrinkage is increased and this reduces rather than improves the bond strength.
Abstract: A new theoretical concept of crack closure under plain strain was applied to assess the
effective fatigue threshold under various loading condition for selected aluminium and titanium
alloys of different microstructures. The concept is based on the long-range effect of geometrically
necessary dislocations remaining in the wake of propagating fatigue cracks. Calculated threshold
values FKeff,th for 7475 aluminium alloy are about 1.9 MPa.m1/2 (in vacuum) and 1 MPa.m1/2 (in
air), and about 2.5 MPa.m1/2 and 3.3 MPa.m1/2 for c-titanium and Ti-2.5%Cu, respectively. All
calculated values are nearly independent on both the microstructure and the applied stress ratio and
they are in a good agreement with experimental data.
Abstract: In this paper, the continuous in-situ observations of the fatigue crack growth in U71Mn and
U75V rail steel are made by using the scanning electronic microscope (SEM). The microstructure
patterns of cracks under the mode I fatigue loads and quasi-static loads are presented. The results
indicate that the short fatigue crack growth in rail steel is a quasi-cleavage fracture. The ductility and
the performance of fatigue resistance of U71Mn rail steel are better than those of U75V rail steel.
Abstract: Fatigue crack initial life of multiple-site structure is described as the shortest life of all
site’s fatigue initial lives. This paper will establish a method, which is described to estimate fatigue
initial life of multiple-site structure. Using finite element method (FEM), the local stress
concentration of each site is calculated. Using the statistical fatigue theory, the fatigue crack initial
probability can be considered. Numerical example indicates: fatigue crack initial life of multiple-site
structure is shorter then the life of single site. At the end of paper, experiment was executed adopting
the same fatigue cycle loads with the computational case. The receivable relative error between the
experimental result and the result of numerical analysis verifies the efficiency of this
Abstract: Many methods can be used to assemble large mechanical structures. Using rivets is one of
these methods. Rivets are lighter than bolts and allows for efficient assembly. The cylindrical
structure has a discontinuous rivet assembled region. So concentration load operates in the edge of
discontinuous assembled region. This paper evaluates the force placed upon rivets used to assemble
cylindrical structures and strength of structures assembled with rivets. Plastic deformation of rivets
occurs at 4 kN and rivets are destroyed at 7 kN. However, rivets are designed to transfer load to
neighboring rivets when they are overloaded. Structural test were accomplished using tension and
bending load condition. The structural tests showed that plastic deformation first occurs in the
fastening where the rivet meets the outside of the cylinder and a number of rivets exhibited this type of
deformation. The secondary phase of deformation occurs in the fastening where the rivet meets the
inside of the cylinder. Despite the plastic deformation, the structural tests showed that the rivets
succeeded in redistributing load to neighboring rivets and as a result, no rivets were destroyed.