Vibrations & Ultrasonic Measurement Systems
Polytec Scanning Vibrometer QTec 3D Laser Doppler Vibrometers (LDVs)
We have the 3D-LDV system from Polytec that provides high-precision, non-contact measurement of surface dynamics across three dimensions, simultaneously. This system is essential for visualizing full-field elastic wave propagation and characterizing the complex dynamic modes of metamaterial structures without the mass-loading effects of traditional sensors.
Related publications:
https://doi.org/10.2514/6.2025-3252
1-D Granular Crystals & Friction Interface Experiment System
We have experimental system designed to investigate the complex interplay between highly nonlinear solitary waves and frictional interfaces at the micro-scale. It utilizes a precision-aligned 1D granular crystal of suspended steel spheres to generate and characterize solitary wave propagation with minimal energy loss from parasitic friction. The granular chain is in contact with a flat semi-infinite boundary with a specialized friction module where an electrodynamic shaker imposes controlled tangential oscillations, allowing the lab to study repeatable frictional hysteresis under high-rate normal loading. By integrating multiple Laser Doppler Vibrometers (LDVs) and dynamic load cells, the setup synchronously captures wave velocities and interface forces to reconstruct real-time contact mechanics. This unique capability enables the WPM Lab to relate wave-steering properties to fundamental contact parameters, providing critical insights into energy dissipation and tunable vibration control.
Related publications:
https://doi.org/10.1121/10.0037895
RITEC Advanced Measurement System RAM-5000
The RITEC RAM-5000 is a high-powered ultrasonic measurement system designed for advanced material characterization and nonlinear acoustics measurements. This system generates high-energy RF bursts that are required to investigate material nonlinearities and wave interactions at ultrasonic frequencies. The WPM lab uses this system detect dislocation-based material degradation by measuring higher harmonic generation. We also have a range of attenuators, diplexers, preamplifiers, and filters tuned specifically to this RITEC system to enable a range of ultrasonic NDE-based measurements. The lab also contains a suite of contact ultrasonic transducers ranging from 0.75-25 MHz, air-coupled transducers, and high-resolution oscilloscopes for advanced ultrasonic characterization of materials.
Related publications:
https://doi.org/10.1016/j.ultras.2023.106945
https://doi.org/10.1007/s10921-021-00828-z
https://doi.org/10.1016/j.ndteint.2025.103401
Stanford Research Systems Lock-In Amplifiers (SR830, SR844, SR860)
These Lock-In Amplifiers are utilized to extract small AC signals from high-noise environments with extreme precision. They are critical for sensitive experimental measurements of acoustic and mechanical responses where signal-to-noise ratios are low. These amplifiers are used to experimentally characterize the frequency response of, e.g., 3D printed phononic crystals fabricated from viscoelastic polymers, and conduct nonlinear resonant ultrasound spectroscopy measurements to quantify nonlinearity in materials/structures.
Dynamic Magneto-Mechanical Analyzer (DMMA)
Our custom-built DMMA setup provides state-of-the-art experimental capability for characterizing the dynamic response of magnetoactive elastomers (MAEs) under coupled mechanical and magnetic loading. Built on an optical table for vibration isolation, the setup uses a piezoactuator-driven compression stage, dynamic force sensing, and phase-locked lock-in measurement to quantify complex modulus with high sensitivity. With operating ranges of 1–600 Hz, 0.02–30 μm harmonic displacement amplitude, and magnetic fields up to 0.17 T, the platform enables detailed investigation of frequency and amplitude-dependent magneto-mechanical behavior in magnetoactive elastomers.
Related publications:
https://doi.org/10.1007/s11340-024-01115-4
Shakers (B&K 4809, 4810) and Impact Hammer (PCB 086C03)
These tools at our lab serve as the primary excitation sources for various dynamic structural testing and vibration analysis. They are used to induce controlled mechanical waves to measure frequency response functions (FRFs) and dispersion behaviors in experimental samples and setups. The shakers can generate excitations of specific waveforms such as sine bursts, periodic chirp, and random signals. B&K 4809 is suitable for exciting structures with higher mass and stiffness compared to B&K 4810, the mini shaker. On the other hand, the impact hammer has embedded force transducer. The tip of the hammer can be changed depending on the effective mass and stiffness of the test specimen and the frequency range of interest. These excitation methods are critical for extracting the modal parameters and damping characteristics necessary to verify the structural integrity of complex mechanical assemblies.
3D Printing & Optical Facilities
Hyrel System 30M 3D Printer
We have a modular, multi-material 3D printer capable of processing a wide range of functional materials, including pastes and flexible polymers. The versatile head system allows for the creation of multi-functional and composite structures for advanced wave-steering applications. The integration of multi-functional material deposition allows for the development of adaptive metamaterials with embedded sensing and actuation capabilities.
Formlabs 3D Printing Suite (Form 2, 3+, Wash, and Cure)
We have high-resolution stereolithography (SLA) setup used for the precise fabrication of complex 3D architectures and metamaterial unit cells. The integrated washing and curing stations ensure that printed samples achieve their intended mechanical properties and surface quality. The use of these additive manufacturing technologies facilitates a rapid design-to-validation pipeline for exploring the physics of architected cellular solids.
Related publications:
https://doi.org/10.1016/j.ijmecsci.2026.111524
https://doi.org/10.1115/1.4044135
https://doi.org/10.1121/10.0024610
Magnetoactive Elastomer (MAE) Fabrication
We have the capability to fabricate magnetoactive elastomers (MAEs) with both isotropic and anisotropic particle distributions using controlled processing conditions. Our fabrication setup, including FlackTek SpeedMixer DAC 150-FVZ-K, allows us to tailor microstructure and particle alignment to study how internal architecture influences the mechanical and magneto-mechanical behavior of these materials.
Optical microscopy images of magnetoactive elastomers:
Related publications:
https://doi.org/10.1016/j.eml.2025.102368
https://doi.org/10.1016/j.engfracmech.2024.110553
https://doi.org/10.1007/s11340-024-01115-4
Olympus BX53M Optical Microscope
The Olympus BX53M upright materials microscope supports high-resolution inspection of fabricated samples and microstructural features using multiple observation modes, including brightfield, darkfield, and polarized light. These capabilities make it well-suited for examining particle distribution, surface quality, and fine structural details in soft composites, additively manufacture composites, and related materials.
Optical microscopy images of binder-jet manufactured composite:
Related publications: