A finite element model of the axially-loaded bolts was established to investigate their shock response characteristics. The test clamps for suspending and horizontally mounted bolts were manufactured. Data groups of acceleration response were obtained through the shock experiment. The acceleration and stress responses of the bolt connections were surveyed through the explicit dynamic analysis. Mutual comparison of simulation results and experimental results has verified the reliability of the application of the FEM method.

Testing equipment buffering platform can provide a reliable working environment for testing equipment, and offer an impact protection, stable power supply and sufficient operating space in the progress of impact test. Buffering platform is an elastic platform supported by FD40-10 air springs and polyurethane damper blocks. The platform was fitted out an isolation transformer and a high-power uninterrupted power supply according to the requirement of ship’s electrical power system. Based on theoretical analysis, laboratory test and practical equipment impact test, it is demonstrated that testing equipment buffering platform is necessary for reliably acquiring testing data during the impact test.

The ultimate shock load of KA-100 bending rubber vibration isolator was investigated experimentally. In addition, numerical simulation was carried out to simulate the anti-shock performance of the isolator. Using the Yeoh hyperelastic model, viscodamping method and ABAQUS code, the ultimate shock load of the isolator was analyzed considering geometrical non-linearity effect. Good agreement between the numerical results and experimental results proves the efficiency of the numerical method.

A mechanical model of a six-rod shock-isolation mount with different crash-constraints was established. The dynamic characteristics of the shock-isolator were studied. A shock test was then carried out for the six-rod shock-isolation mount. The shock response and several key points for design of the six-rod shock-isolation mount were summarized through the comparison between theoretical and experimental results.

The auto-regressive(AR) model of exhaust noise in diesel engine’s seven operating modes about the valve train was established. The auto-regressive parameters were regarded as the characteristic vectors to build the fault diagnosis model which was based on extreme learning machine. The proposed method was also compared with that of BP neural network, RBF neural network and support vector machine. Experimental results show that exhaust noise can be used for fault diagnosis in diesel engine’s value train. The classification accuracies of above four different intelligent methods are all higher than 95%. But the method of extreme learning machine has advantage apparently in training rate.

bstract : The μ multi-objective genetic algorithm is used to optimize the damping values of the controllable vibration damper. The damping parameters of the front and rear suspension are selected as the optimization variables, and the MSR values of the body vibration acceleration, the suspension travel movement and the tyres dynamic displacement are selected as the optimization objective. The three-levels damping values of the controllable vibration damper are optimized design by considering the characteristics of the different load, speed and road surface level for the suspension system at the same time. According to the optimization results, the three-levels damping values of the controllable vibration damper are confirmed, i.e. "soft-middle-hard". The suspensions simulation test proved that this algorithm is a kind of high efficiency of the multi-objective global optimization method.

In order to study the effects of viscoelastic dampers on fatigue behavior of steel trusses, the equivalent stiffness of viscoelastic dampers was derived. Based on random load, and according to load’s power spectral density（PSD）, structure’s frequency response and the structure’s modal, the fatigue behavior of the steel trusses were calculated and compared. These working conditions included that there was no viscoelastic damper added to the structure and that there were viscoelastic dampers with different damping coefficients respectively added to the structure. The result indicates that viscoelastic dampers can extend the structure’s fatigue lifespan efficiently. It is found that with the increase of the damping coefficient, the structure’s fatigue lifespan increases at first and decreases thereafter. Therefore structure’s fatigue resistant ability can be optimized through the best choice of the damping coefficients.

Based on acoustic FEM, the transmission losses of three mufflers with different combinations of perforated tubes were computed. The influences of the perforation porosities of the tubes on the transmission losses of the mufflers were discussed. Then, the acoustic performance of a complicated muffler with multiple perforated tubes was stimulated. The result shows that the transmission loss of the muffler is low when the noise frequency is below 1 000 Hz. This work provides a reference for further improvement of the muffler.

The practicality and reliability of computation model are the key problems in model building. The dynamic model of the linear system does not adapt to the nonlinearparameter system. In this paper, the stiffness and damping parameters of an engine mount system are obtained in experiments. The corresponding mass matrix and stiffness matrix are used for establishing the dynamic computation model of the engine mount system. The model is validated by relative analysis of operational modal and calculated modal. Results indicate that the computation model including dynamic stiffness parameters is more practical than the traditional model of static stiffness.

The principle of speech enhancement and the method of extracting speech signals from strong noise background are introduced. Three kinds of speech intensifying algorithms based on spectrum subtraction algorithm, wiener filtering and wavelet transform, respectively, are comparatively studied. However, the two purposes of the speech enhancement algorithms, to enhance articulation and to enhance the understandability, are not related each other, and even in contradiction sometimes. Therefore, a good speech enhancement algorithm is in fact a compromise between the two purposes according to the requirement of application. In this paper, results of numerical experiment of the three algorithms are compared and studied. The results demonstrate that the speech enhancement algorithm using wavelet ransform is more efficient than the others.

The problem of noise pollution and energy waste of a boiler room in a residential area of Dalian city is studied in this paper. The causes which induce excessive noise and energy waste are investigated by analyzing sound source and propagation path of the noise. Then a method, that can reduce both internal and external noises of the boiler room and can save energy, is proposed. A good effect in engineering application is obtained.