Single-contact resonance spectroscopy specialized for rapid part examination and qualification through detection of voids and elastic property differences (porosity or material changes).
LARS
Single-contact nondestructive testing using Laser Acoustic Resonance Spectroscopy
Why LARS?
Technical services for single-contact nondestructive testing using Laser Acoustic Resonance Spectroscopy
Rapid Part Inspection
Quickly determine which parts meet their specifications using our proprietary machine learning algorithms
Single Contact
Only a single transducer needed, avoiding nests of wires and lengthy setup
No special part Preparation
Parts can be examined as supplied
Fast Turnaround
Simple part setup and heavily automated data collection means you get your results fast
Precise
Detect small anomalies in a part’s elastic properties, internal structure, or dimensions
Identify Counterfeits
Determine whether a part is made of the right material and has the right internal structure
Revealing
Measure mode shapes to reveal detailed vibrational behavior of parts
Affordable
Eliminate or reduce your need for expensive CT scans to verify internal structures
Flexible
Immediately measure any metallic part from 0.1 to 2 kg. This range can be expanded as requested - contact us!
Customizable
We can accommodate your specialty nondestructive testing needs!
LARS WORKFLOW
Laser Acoustic Resonance Spectroscopy for rapid and accurate parts qualification, defect identification, and materials property verification.
Sample Preparation and Setup
For almost all metallic parts, this involves only placing the part on a net with a piezoelectric transducer contacting it from below.
Vibration and collection
A piezoelectric transducer excites the part at frequencies up to 80 kHz and a laser Doppler vibrometer measures the vibrational spectrum of the part at various points.
Data Processing
A proprietary machine learning classification algorithm allows pass-fail criteria to be evaluated instantly. Detailed analysis of vibrational spectra or mode shapes is also available.
Data Analysis
Pass-fail results, vibrational spectra, elastic properties, mode shape information, and more are measurable with LARS.
DEMONSTRATIONs
Application of LARS to internal void detection in an additively manufactured bracket
Our LARS instrument has been used to rapidly qualify additively manufactured brackets with internal voids, identify groups of different types of voids, and identify the location of voids in the internal structure. Measurements take only a few minutes per part and qualification results are available nearly instantly using our proprietary machine learning algorithms. Our clustering algorithm can identify groups of parts with similar defects to determine if a process caused consistent defects. With more measurement time, LARS can reveal detailed images of resonant mode shapes, which for some defect types directly reveals the defect location.
Printed brackets with intentional voids were created, with small, medium, and large voids at two different locations (A and B).
With no prior knowledge of the brackets, the defect types were automatically and correctly clustered by MetroLaser’s machine learning methods.
For even faster processing and clarity about which of the clusters are good parts, the brackets can be classified as defective or good, given a single good reference part.
Application of LARS to FE model validation for a rectangular bar
LARS is exceptionally sensitive to minor variations in elastic properties and part dimensions. Our LARS instrument has been used to precisely validate a FE model of a metallic bar by comparing the resonance modes measured by LARS with those calculated by FEA. Using statistical methods, an initial FE model is iteratively updated to match the measured resonance modes, thereby creating a validated and extremely precise FE model of a part.
Mode shape measurements allow matching between measured and calculated frequencies with complete confidence.
Even for very symmetric parts (e.g., a bar), peaks associated with different mode shapes shift differently due to changes of dimensions and elastic properties. This principle remains true for complex parts, so key dimension variations and elastic properties can be precisely identified.
Two bars made from low carbon steel (LCS) and 303 stainless steel (303SS) were measured. Because both the modulus and Poisson’s ratio differ between the alloys, bending modes (green) differed by a scaling factor 6.3% while torsion modes (orange) differed by 3.7%. This implied a 13% difference in 𝐸 and a 22% difference in 𝜈.
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MetroLaser will continue to pursue state-of-the-art research and development as well as the commercialization of optical diagnostics systems to measure flow velocity, temperature, chemical composition, surface temperature inside gas turbine engines, and non destructive inspection of composites and other components.