Abstract: Forced vibrations can lead to an irreparable damage of a blade array. Devices called “underplatform
damper” that dissipate the vibration energy are employed in order to reduce blade vibration
amplitude. The present paper deals with the design of the underplatform damper. A numerical code
to calculate the forced response of a blade array with dampers has been previously purposely
developed. A method is here proposed for the estimation of the unknown contact parameters
demanded by the code. The computation results are here validated by means of comparison with
experimental results on a static test rig. Three dampers with different shape are tested.
Abstract: According to the fatigue damage failure mechanism of riveted members, a riveted member
probabilistic fatigue failure model (RMPFFM) was proposed, and a fracture finite element program is
developed to calculate the geometry function of RMPFFM. Furthermore, a system fatigue damage
reliability model of riveted bridges was proposed, and based on Monte-Carlo method, a large system
fatigue damage reliability analysis program was developed to calculate the system fatigue failure
probability. Then the system evaluation model was used to predicate the system fatigue damage
reliability of Ganjiang Railway Bridge. According to assessment results, the probabilistic remaining
fatigue life, safe inspection intervals and maintenance strategy are determined, which can control and
avoid fatigue failure accident and reduce the contingent disaster in bridge service life.
Abstract: Three RC slab specimens were designed and manufactured to investigate the fatigue
behavior of RC slab retrofitted with carbon fiber mesh (CFM) and mortar. Among three slab
specimens, two slabs were pre-loaded to introduce damage prior to the fatigue loading tests. Fatigue
loading was applied to the top of slab maintaining 40% of the ultimate strength of specimen at 2Hz
loading speed. The fatigue test was terminated when the loading cycle exceeded 1,000,000 cycles.
From the test results, the effectiveness of the retrofitting using CFM was evaluated. Test result
showed that the specimens retrofitted after either severe or light damages had very similar strength
and stiffness to those of the specimens retrofitted without damage. It was found that the strength was
even slightly improved in the specimen retrofitted with CFM.
Abstract: The findings of a year-long programme carried out by a multidisciplinary
engineering/conservation team are described. A mass-produced textile material that can be used to
represent tapestries is identified and mechanical tests are detailed which demonstrate it behaves in a
similar way to tapestry. The feasibility of using optical fibre sensors, full-field optical strain
measurement techniques and thermography for monitoring tapestry degradation is assessed. The
results of preliminary findings are presented and a rationale is developed for in-situ quantitative
strain monitoring of tapestries.
Abstract: The wave reflection coefficients of damage such as cracks, notches and slots in otherwise
uniform beams depend on frequency and on the size of the damage. Experimental results are
presented for the wave power reflection coefficients of transverse slots of various depths sawn into
a number of beam specimens. These results are compared with a conventional spring model to
estimate the depth of the slot. The method appears to work well for larger slot depths (greater than
about 30% of the thickness of the beam) and at higher frequencies, allowing their existence to be
inferred and their size to be estimated. This is due to the fact that the reflection coefficients are
larger in these regimes. For smaller slots or at low frequencies, noise and experimental errors, such
as miscalibration errors and ill-conditioning, become more significant.
Abstract: In this paper the damage assessment of nanostructures is discussed. As an example we
assess the damage of nanobeams with non destructive dynamical resonance or destructive tensile
tests: a small number of nanocracks, i.e., ~10, with length of ~1nm, is accordingly estimated.
Abstract: This work was conducted as part of the European Union project ARTIMA and it
investigates the potential for a dual use active constrained layer damping treatment for both
vibration control and structural health monitoring. It examines a curved aluminium plate with an
ACLD treatment formed by mounting a large piezoceramic patch with Araldite 2027. The plate was
investigated by ultrasonic Lamb waves generated by the patch, and several smaller piezoceramic
transducers were used as sensors. Damage was simulated by adding incrementally increasing saw
cuts to the plate, and the technique of outlier analysis was used to classify when this damage had
Abstract: This study investigates a possibility for representing, interpreting and visualising the
vibration response of aircraft panels using time domain measurements. The aircraft panels are
modelled as thin orthotropic plates and their vibration response is simulated using FE modelling.
The vibration response of a thin aluminium panel is simulated using FE modelling. The first ten
resonant frequencies are estimated for the FE model and for the dynamically tested panel. They
were found to show somewhat low sensitivity to damage. Then the simulated vibration response of
the panel is transformed and expanded in a new phase space. This presents an alternative way to
study and analyse the dynamics of a structure. A two dimensional phase space is used in this
investigation. Thus instead of studying the single dimension measured vibration characteristics one
is faced with expanded two dimensional variables which can be visualised and this facilitates the
comparison between the damaged and the non-damage states.
Abstract: Modal models are commonly encountered forms of dynamic characterization of
mechanical structures. They are applied in machine-condition diagnosing as well as in monitoring
processes. In research practice the most frequently applied method is Experimental Modal Analysis,
and in exploitation - Operational Modal Analysis. Difficulties associated with the EMA and OMA
have contributed to the increase of OMAX model applications, especially in case of energetic
Theoretical assumptions related with modal analysis are very strong. In reality when big and heavy
structures are considered often those assumptions are not fulfilled. In the paper such situations are
considered and practical solutions are showed.