In the late 1980’s and early 1990’s smart structures seemed to be the only solution to add enough damping to the kind of lightweight, high performance beam director that was a key component of a Space Based Laser. This drove construction of what may be the world’s largest smart structure with 16-foot-long metering struts with 100’s and 100’s of embedded piezoceramics. The same technology was an excellent choice to make guitars sound better. Some current applications of smart structures at Boeing will also be discussed.

The field of adaptive structures and materials systems is multi-faceted and multidisciplinary, and therefore is poised to play a prominent role in the future of engineering research and technology development. In fact, many of our community members are already comfortable working across disciplines and institutional boundaries in convergent research teams. This presentation will highlight some my own work and experiences in collaborative research teams, specifically in the optimal design of adaptive structures targeted at applications ranging from aerospace systems to medical devices. Some projections and suggestions for future research directions to continue the positive trajectory of our research community will be addressed as well.

Understanding resonant characteristics of stub resonator

The advanced displacement measurement technique using computer vision has shown several advantages, such as high spatial resolution and no mass loading effect, compared to conventional sensing techniques. However, the accuracy and robustness of vision-based techniques are subjected to the various conditions, including uneven illumination and insufficient lighting. This study introduces an accurate 2-dimension displacement measuring technique with high robustness to the illumination change, which uses two complex Gabor filters and a specially designed marker. The linear phase can be generated around the marker by optimizing the filter parameter for accurate motion estimation. The nonlinearity caused by the complex conditions, such as low light and uneven illumination, can also be reduced by emphasizing marker features. Phase-based optical flow is further employed to extract the displacement based on the extracted phase. The measurement performance is compared with Laser Doppler Velocimetry (LDV) to validate the proposed technique under various lighting conditions and its robustness is demonstrated. The proposed technique is also applied to different structures to show the ability of measuring high-accuracy displacement signals under various conditions.

High-rate dynamic systems are defined as systems that undergo large levels of acceleration, often over 100g, over short durations, typically less than 100 ms. Examples of such systems include active blast mitigation mechanisms, adaptive air bag deployment, and hypersonic systems. Their dynamics is uniquely characterized by 1) large uncertainties in the external loads; 2) high levels of nonstationarities and heavy disturbances; and 3) unmodeled dynamics generated from changes in system configurations. High-rate structural health monitoring (HRSHM) is concerned with the development of sub-millisecond state estimation capabilities in order to facilitate the future implementation of decision systems to improve the safety and operation of high-rate systems.

Deterioration modeling is a key task in bridge maintenance planning. Advanced deterioration modeling offers ability to focus maintenance action to where and when they are most needed. In this paper, we use a neural network survival model to estimate the time bridge decks remain in a given condition. We explore a flexible method of modeling bridge deck survival probabilities, aimed at informing the integrity management process. We combine the neural network approach with the traditional physical deterioration models to create a physics-informed survival model.

Shape memory alloys (SMAs) have long been utilized as semi-active elements for the attenuation of unnecessary vibration in engineering structures. By leveraging properties of different material phases, energy dissipation capability of smart structures integrated with SMAs can be enhanced and a certain degree of tunability subjected to temperature or stress stimuli can be achieved. In this paper, the influence of axial pre-strains on the dynamic characteristics of a pinned-pinned beam at different operating conditions was systematically and comprehensively investigated. To model the material nonlinearity of SMAs, the improved one-dimensional (1D) Brinson's model with tension-compression asymmetry is exploited. The constitutive relation was integrated into the finite element model of considered SMA beam, in which geometric nonlinearity in the von Karman sense is included as well. Free and forced vibration of the SMA beam under different levels of pre-strains as well as operation conditions were analyzed. For the free decaying of SMA beam, it was observed there exists optimal pre-strain that can achieve maximum damping performance. In the forced vibration analysis, the jump phenomena in amplitude-frequency properties of SMA beam were evaluated and compared to the equivalent elastic beam. The results imply that the pre-strains affect the vibration of SMA beam distinctly at different operating temperatures as well as frequency regions. The conducted analysis can provide guidance on fully exploiting dissipation properties of SMA lamina in the development of composites.