The integration of smart materials such as piezoelectric devices and shape memory alloys into structures has been typically limited to a bonding process that occurs as a secondary operation. Such an operation is not only costly for high volume applications but also has the potential of degrading the performance of the actuator or sensor due to the bonding agent selected. The work presented here explores the integration of piezoelectric materials using a high volume injection molding process. The process used is typical for large automotive components such as bumpers, instrument panels and other body panels. Different materials were evaluated, including plastics and both bare and packaged smart materials. Temperature and flow rate were also changed to investigate the effects on the durability of the materials. Both electrical and mechanical properties were tested with the key parameters including, void content, shifting from initial position, strain transfer and peal strength. It was found that good integration of piezoelectric materials could be achieved and electro-mechanical properties were improved as compared to a secondary bonding operation. Integration of screen-printed electrical circuits for electrical connectivity for piezoelectric materials will be evaluated in future research. In conclusion, a step forward was made in developing a multifunctional material based upon smart materials and conventional high volume manufacturing processes.
This paper reports an experimental study on active vibration reduction for automotive shafts with the use of piezoelectric material. The work focuses on an axle of an Audi A2. The demand in the automobile sector for higher comfort in the vehicle is of a great importance alongside the requirements of lighter weight and low fuel consumption. These requirements are typically in conflict with each other. One solution is the use of intelligent materials instead of viscoelastic materials and proof mass absorbers. These solutions are quite heavy especially at low frequencies. Active vibration control and piezoelectric devices are advantageous in this application due to their low mass to performance ratio. Our research study explores the use of such piezoelectric devices for an axle. In conjunction with electronics it will reduce vibrations in the first natural bending mode of the axle. Laboratory tests simulated the condition present in the road. At first a stationary set up was used, then a simulated disturbance was input at the attachment points of the shaft. Finally, a test with rotating shaft was performed. Piezoelectric devices (custom QuickPacks from ACX, a Division of Cymer) were used as sensors and as actuators to properly control the axle during the different operating conditions. The power consumption of each actuator pair was less than 20W. The work described here details the test setup, the control strategy, the hardware implementation as well as the test results obtained.
Several sports are based upon a tool (club, bat, stick) striking an object (ball, puck) across a field of play. Anytime two structures collide, vibration is created by the impact of the two. The impact of the objects excites the structural modes of the tool, creating a vibration that can be felt by the player, especially if the hit is not at a `sweet spot'. Vibration adversely affects both feel and performance. This paper explains how piezoelectric dampers were developed to reduce vibration and improve the feel of ball-impact sporting goods such as golf clubs. The paper describes how the dynamic characteristics of a golf club were calculated, at first in the free-free condition, and then during its operation conditions (the swing of the club, and the impact with the ball). The dynamic characteristics were used to develop a damper that addressed a specific, or multiple, modes of interest. The damper development and testing are detailed in this paper. Both objective laboratory tests and subjective player tests were performed to evaluate the effectiveness of the piezoelectric dampers. The results of the tests, along with published medical data on the sensitivity of the human body, were used to draw a correlation between human feel and vibration reduction.
KEYWORDS: Finite element methods, Vibration control, Control systems, Prototyping, Resistors, Modal analysis, Data modeling, Analytical research, Semiconducting wafers, Lead
This paper explains how piezoelectric devices can be used to control vibrations in a snowboard. Furthermore the details of the approach, testing, design and analysis of a piezoelectric damper applied to a production snowboard are described here. The approach consisted of determining the principal modes of vibration of a snowboard during its operation (on-slope). This information was used to develop a finite element model of the structure. The finite element model was used to find the areas of higher strain energy where a piezoelectric device could be applied and be effective in reducing undesired vibrations. Several prototype piezoelectric dampers were built, applied to snowboards and tested on snow. The proper amount of damping was selected by the test riders, so that a configuration could be selected for production of the 1998 K2 Electra snowboard. The piezoelectric damper selected reduced the snowboard vibration by 75% at the mode to which it was tuned, allowing for a smoother ride and a more precise control of the snowboard in any kind of snow condition.
Conference Committee Involvement (2)
Industrial and Commercial Applications of Smart Structures Technologies
16 March 2004 | San Diego, CA, United States
Industrial and Commercial Applications of Smart Structures Technologies
4 March 2003 | San Diego, California, United States
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