Hanling Mao

Semantic hyper-graph-based knowledge representation architecture for complex product development

Abstract More and more manufacturing companies are facing challenges in knowledge refining and reusing in stage of product development. To resolve this problem and make the knowledge convenient for acquisition, machine-understandable and human-understandable, this paper proposes a framework of semantic hyper-graph-based knowledge representation to support the knowledge sharing for the product development. A case study of car headlamp development is given to validate the feasibility and effectiveness of the proposed method. The results bring out that it can help engineers to rapidly and accurately acquire knowledge. In future research, the knowledge recommendation service based on product development process should be considered.

Fatigue crack detection and fatigue damage imaging using the non-collinear transverse wave mixing technique

ABSTRACT For the fatigue crack embedded in metallic components, the non-collinear transverse wave mixing technique is applied to detect them and image the fatigue damage around crack. When two non-collinear transverse waves with same frequency meet in components, a resonance longitudinal wave can be generated if the resonance condition is satisfied; the mixing nonlinear parameter is applied to evaluate the nonlinearity of detection positions. The non-collinear wave mixing experiments are conducted on components with different length of fatigue crack. By changing the relative position of transducers, different detection positions can be controlled. According to the distribution of mixing nonlinear parameter at vertical direction, the length of fatigue crack at vertical direction can be measured. Furthermore, the mixing nonlinear parameters of different detection positions around fatigue crack are measured, the image of mixing nonlinear parameter can visualise the damage around fatigue crack which is very easy to assess the fatigue damage of components.

Fatigue Life Prediction of Metallic Materials Based on the Combined Nonlinear Ultrasonic Parameter

The fatigue life prediction of metallic materials is always a tough problem that needs to be solved in the mechanical engineering field because it is very important for the secure service of mechanical components. In this paper, a combined nonlinear ultrasonic parameter based on the collinear wave mixing technique is applied for fatigue life prediction of a metallic material. Sweep experiments are first conducted to explore the influence of driving frequency on the interaction of two driving signals and the fatigue damage of specimens, and the amplitudes of sidebands at the difference frequency and sum frequency are tracked when the driving frequency changes. Then, collinear wave mixing tests are carried out on a pair of cylindrically notched specimens with different fatigue damage to explore the relationship between the fatigue damage and the relative nonlinear parameters. The experimental results show when the fatigue degree is below 65% the relative nonlinear parameter increases quickly, and the growth rate is approximately 130%. If the fatigue degree is above 65%, the increase in the relative nonlinear parameter is slow, which has a close relationship with the microstructure evolution of specimens. A combined nonlinear ultrasonic parameter is proposed to highlight the relationship of the relative nonlinear parameter and fatigue degree of specimens; the fatigue life prediction model is built based on the relationship, and the prediction error is below 3%, which is below the prediction error based on the relative nonlinear parameters at the difference and sum frequencies. Therefore, the combined nonlinear ultrasonic parameter using the collinear wave mixing method can effectively estimate the fatigue degree of specimens, which provides a fast and convenient method for fatigue life prediction.

Product lifecycle–oriented knowledge services: Status review, framework, and technology trends

More companies are facing challenges in extracting and utilizing knowledge in product lifecycle. To solve this problem, a product lifecycle–oriented knowledge service framework is proposed based on the status review. The proposed framework is supported by four key methods and processes, which include mechanism of knowledge service identification, mechanism of product knowledge service transfer, delivery process of product knowledge service, and performance evaluation of product knowledge service. Different with most of the previous fragmental studies, the proposed systematic knowledge service framework is mainly product lifecycle oriented. In addition, an application in gantry crane design shows that the proposed framework can provide effective lifecycle knowledge support for product development, which will help to promote concurrency and simultaneity in product development process.

Feasibility of Residual Stress Nondestructive Estimation Using the Nonlinear Property of Critical Refraction Longitudinal Wave

Residual stress has significant influence on the performance of mechanical components, and the nondestructive estimation of residual stress is always a difficult problem. This study applies the relative nonlinear coefficient of critical refraction longitudinal ( ) wave to nondestructively characterize the stress state of materials; the feasibility of residual stress estimation using the nonlinear property of wave is verified. The nonlinear ultrasonic measurements based on wave are conducted on components with known stress state to calculate the relative nonlinear coefficient. Experimental results indicate that the relative nonlinear coefficient monotonically increases with prestress and the increment of relative nonlinear coefficient is about 80%, while the wave velocity only decreases about 0.2%. The sensitivity of the relative nonlinear coefficient for stress is much higher than wave velocity. Furthermore, the dependence between the relative nonlinear coefficient and deformation state of components is found. The stress detection resolution based on the nonlinear property of wave is 10 MPa, which has higher resolution than wave velocity. These results demonstrate that the nonlinear property of wave is more suitable for stress characterization than wave velocity, and this quantitative information could be used for residual stress estimation.

Chaotic characteristics analysis of simulation signal of ultrasonic nonlinear modulation effect

The effectiveness of chaos and fractal theory in analyzing ultrasonic nonlinear modulation signal was theoretically verified and a new way of using chaos and fractal theory in nondestructive testing is provided based on the simulation signal of ultrasonic nonlinear modulation effect. By constructing the simulation signal of modulation effect, the simulation signal with the chaotic character was found, and the nonlinear parameter and characteristic values of chaos theory were calculated to analyze the nonlinearity of specimens. By comparisons, the conclusion could be found that the Lyapunov exponent was sensitive to weaker nonlinearity and unsusceptible to noise.

Deducing and verifying the frequency equation set of dual-frequency piezoelectric transducer

Two different operating frequencies were required in dual-frequency piezoelectric transducers, a frequency equation set that satisfy with the requirement were deduced in this paper. Some different dual-frequency piezoelectric transducers were designed; then modal analysis and frequency response analysis for these transducers model were completed with ANSYS software, the frequencies obtained by simulation were very close to the design values. Thereby the frequency equation set has been verified.