Ultrasonic Waves and Structural Health Monitoring (SHM) System

Ultrasonic and Acoustic Wave Technology

At Piezo Smart, we specialize in advancing research and development in ultrasonic and acoustic wave technology, a field that has broad application across industries such as non-destructive testing, industrial automation, environment monitoring, and medical diagnostics. Our expertise lies in harnessing the principles of wave mechanics to create innovative solutions using piezoelectric materials that address complex challenges, enabling precision, efficiency, and safety.

Introduction to ultrasonic and acoustic waves

Ultrasonic waves are sound waves that have frequency beyond the upper limit of human hearing, typically above 20 kHz. Acoustic waves refer to all sound waves, encompassing both the audible range (20 Hz to 20 kHz) as well as ultrasonic frequencies. These waves are mechanical vibrations that propagate through different mediums such as air, water, and solid materials, and their behavior is influenced by the medium’s properties.

In the context of technology, the control, generation, and detection of these waves offer a multitude of capabilities. The interaction of ultrasonic waves with materials enables a wider range of industrial and scientific applications, from material characterization to imaging.

Key Characteristics of ultrasonic waves:

Frequency: Ultrasonic waves have frequency above 20 kHz, and higher frequencies (up to several GHz) offer better resolution in certain applications.
Wavelength: The wavelength of ultrasonic waves is smaller than of audible waves, allowing them to detect smaller objects or finer material details.
Propagation speed: The speed at which these waves travel depends on the medium’s density and elastic properties.
Penetration and reflection: Ultrasonic waves penetrate materials and reflect at interfaces where there are changes in acoustic impedance that is useful in imaging and flaw detection.

Scientific Principles Underlying Ultrasonic Technology

Wave Propagation

Ultrasonic waves can be generated by piezoelectric ultrasonic transducers that convert electrical signals into mechanical vibrations. These waves propagate through a medium in four primary modes:

Longitudinal bulk waves are a type of mechanical wave where the particles of the medium move in the same direction (parallel) as the wave’s propagation. This mode is common in solids, liquids, and gases.

Shear bulk waves are characterized by particle motion that is perpendicular to the direction of wave propagation. This mode is common in solid as the states of fluid and gas lack of the necessary shear strength to support this kind of wave motion.

Guided waves are a special type of wave that is constrained to propagate along specific geometrics, such as surfaces, layers, or within confined structures. These waves travel along boundaries or interfaces between materials, guided by the structure they are constrained within, such as pipelines, plates, or composite layers. These waves are particularly useful for inspecting large areas with minimal invasive methods as they travel along the structure covering the whole thickness of the structure.

Surface waves are a specific category of guided waves that propagate along the interface between two media, most commonly along surface of solid materials at the boundary between solid and air. The particle motion in surface waves is typically elliptical, comprising both longitudinal and shear motion components, concentrating on the surface of a structure. One of the key attributes of surface waves is their sensitivity to surface discontinuities, making them exceptionally valuable for detecting sub-surface defects along surfaces.

Wave propagation in a medium is influenced by factors such as:

Elasticity and density of the material.
Reflection, refraction, and absorption of the waves at material boundaries.
Attenuation (loss of energy) due to scattering and absorption in the medium.

Applications of Ultrasonic and Acoustic Technology

Medical Imaging

In healthcare, ultrasonic waves play a crucial role in diagnostic ultrasound imaging, where high-frequency sound waves are transmitted into the body, and the reflected echoes are analyzed to generate real-time images of internal structures. This non-invasive technique is widely used to visualize organs, tissues, and blood flow, providing detailed insights without the risks associated with ionizing radiation.

In addition to diagnostics, ultrasound is used therapeutically in treatments like lithotripsy, where focused sound waves break down kidney stones, and tissue ablation, which targets and destroys abnormal tissues, such as tumors or fibroids, offering a non-invasive alternative to surgery.

Structural Health Monitoring (SHM)

SHM is vital in industries like aerospace, automotive, and civil engineering for assessing material integrity non-intrusively. Applications includes:

Flaw monitoring: identifying cracks, voids, or inclusions in metals, composites, and welds.
Thickness monitoring: monitoring wear and corrosion in pipelines, structures and components. Case study: Localized thickness monitoring
Imaging: Capturing the internal structure of a material through methods like ultrasonic tomography.

More details about Ultrasonic SHM

Industrial Automation and Robotics

In industrial settings, ultrasonic sensors are widely used for proximity sensing and distance measurement. These sensors offer advantages such as high precision, durability in harsh environments, and the ability to detect a wide range of materials. They are critical in:

Robotic navigation and obstacle avoidance
Liquid level detection in tanks and containers
Quality control processes including verifying the presence of objects or inspecting product dimensions
Piezoelectric sensors can be used for vibration condition monitoring due to their high sensitivity, reliability, and capability to function even in harsh environments. They are critical in:
Early detection of machinery faults including imbalance, misalignment, or bearing wear.
Preventive maintenance by continuously monitoring equipment health to avoid unexpected failures.
Performance optimization by ensuring equipment runs smoothly, reducing downtime and extending operational lifespan.

Environmental Monitoring

Ultrasonic and acoustic wave technology play a critical role in environmental sensing, providing effective solutions for monitoring and detecting various natural and industrial phenomena. Acoustic emission monitoring is commonly used to identify early signs of issues like crack formation in structures or gas leaks in pipelines.

Additionally, ultrasonic transducers are used in geotechnical applications, such as soil characterization, rock integrity testing, and monitoring the stability of foundations or slopes, enabling better management of environmental and structural risks.

Ultrasonic transducers are also used in underwater applications offering efficient solutions for various marine activities. They are critical in sonar systems: for mapping the seafloor, detecting submarines and marine wildlife monitoring. It is also used for underwater communication with acoustic waves as the primary method for communication in marine environments where radio waves are ineffective

Innovations at Piezo Smart

At Piezo Smart, we are pushing the boundaries of ultrasonic and acoustic wave applications through advanced research and engineering. Our core innovations include:

Next-generation ultrasonic transducers: We are developing highly sensitive and energy-efficient piezoelectric ultrasonic transducers that enhance signal precision and range. We offer a diverse selection of piezoelectric materials tailored to meet the needs of various applications, including those operating in high-temperature environments.
Miniaturization: We are pioneering the development of compact ultrasonic devices for portable and wearable healthcare solutions, as well as small-scale industrial systems. Our ultrasonic devices can be engineered to be ultra-lightweight (less than 1g), extremely thin (under 100 µm), and highly conformable, allowing seamless integration with a wide range of host materials and surfaces.
Advanced Signal Processing: Our team is focused on enhancing signal analysis techniques to improve noise reduction and data interpretation in complex environments.

Our research into ultrasonic and acoustic waves is underpinned by rigorous scientific principles and a commitment to innovation. We aim to provide groundbreaking technologies that enhance precision, safety, and efficiency across industries. By leveraging the power of piezoelectric materials and acoustic waves, we continue to drive progress in fields ranging from healthcare to industrial automation, shaping a smarter and more connected world.

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