LMS Test.Lab Structures

Straight-to-the-point structural engineering -

Structural testing used to be a long and complex process involving quite extensive trial-and-error and time-consuming test setups. This is no longer the case. With LMS Test.Lab Structures and the LMS SCADAS system, test engineers perform large-scale modal surveys in hours rather than days. They can focus on identifying root causes of vibration problems and apply powerful analysis tools to explore the best solution for practically every structural weakness. Renowned for its modal testing experience – from impact testing of small structures to large-scale campaigns using hundreds of measurement channels, LMS continues its tradition of cutting-edge expertise and maximal testing efficiency with LMS Test.Lab Structures.

From troubleshooting to virtual model validation…

Structures are test-characterized for many different reasons using methods of varying sophistication and complexity. Engineers can quickly pinpoint and correct a vibration problem by simply identifying structural resonances and dominant forcing mechanisms, or by plotting the structural deformation pattern at a specific frequency. To really understand the structural dynamics in detail, engineers turn to modal analysis to characterize measured force inputs. These modal models can be used to validate and update existing finite element models or used directly as the basis for design modification or multi-attribute studies.

…covered in an integrated testing solution

Since every testing department works differently, LMS Test.Lab Structures offers a fully scalable solution and covers the broadest application scope. Highly flexible, LMS Test.Lab Structures is suitable for a wide variety of applications and differing levels of expertise. So whether a structural dynamics expert needs to make an in-depth review of a system’s structural behavior or a new operator needs to set up a basic test, every LMS Test.Lab Structures user will be able to get the right results to answer mission-critical questions – exactly on time. Testing departments can fully protect their system investment, as LMS Test.Lab Structures can easily be expanded and tuned to their changing needs. Starting with impact testing, users can extend their solution with modal analysis, MIMO testing or operational modal analysis capabilities.

Designed for testing efficiency

Minimal test preparation time

Especially for high channel-count structural tests, the actual measurement time is minimal compared to the preparation time. That’s why LMS Test.Lab Structures offers various time-efficient shortcuts in setup preparation, like customized patch panels, direct data reading from TEDS-enabled sensors, notification of an ICP channel open-circuit condition or troubleshooting tools for cabling and sensor problems.

Rapid geometry definition

Test engineers rely on animated mode shape displays to review test results and draw first conclusions from their test campaign. But reliable and informative mode shapes require correct wire frame models. LMS Test.Lab Structures offers different ways to create these wire frame models in the most efficient way. You can define your geometry via Excel-like tables, import geometry via UFF, LMS CADA-X, CAD or FEA, copy/paste geometry information from Microsoft Excel, or create your model from stored TEDS transducer geometry information. Alternatively, LMS Test.Lab Structures helps you measure geometric coordinates with a hand-held probe or through digital photographs.

Step-by-step guidance

LMS Test.Lab Structures guides users though the entire measurement

process with clear-cut control parameters and automatic online displays. LMS Test.Lab Structures can suggest valid test setup parameters as well as handle customized or company-specific templates. This workflow guidance lowers the threshold for technicians and occasional users, guarantees measurement consistency and overall process efficiency.

Modal analysis made easy

A step-by-step guide

LMS has translated the formerly complex modal analysis process into a logical sequence of experience-proven steps, each embedded in a dedicated LMS Test.Lab worksheet. Through its workflow-based user interface, LMS Test.Lab helps users capture the right type of test data – from modal parameter calculation to analysis validation – faster and easier than ever before.

Mode shapes in a few simple steps

LMS Test.Lab Structures handles the three main modal analysis steps in an automatic way. LMS Test.Lab automatically collects all relevant test data while the user selects a frequency range for analysis. Then, with a single mouse-click, the system poles are determined using a curve-fit in that frequency range. After that, the system calculates the mode shapes associated with all physically significant poles, including global residues and all modal coefficients.

The right results - right from the start

High-quality results have never been so easy to obtain. Users just select the measurements, run the analysis and view the results. That’s it. A single page summarizes all the curve-fits so that any user can easily check that the animated shapes, identified frequencies and damping factors accurately reflect the analyzed structure.

Achieving the best possible data quality

Immediate operator feedback

High-quality impact measurements require technicians to really concentrate on hitting right: striking the right point, in the right direction, not too hard, not too soft. LMS Test.Lab Structures makes the job as comfortable as possible. The system gives audio feedback on triggering, overload or completed measurements. It automatically rejects overload and double impact, auto-saves valid measurements and automatically increments measurement point IDs. For shaker tests including MIMO FRF measurements, simply push the start button - the system does the rest.

Measurements you can trust

Before tearing down the test setup, you need to be sure that all the collected measurements are correct and complete. With built-in checklist and self-check features, LMS Test.Lab Structures practically eliminates the risk of having to redo the test. LMS Test.Lab Structures lets operators inspect large sets of measurement data very efficiently. To guarantee data set completeness, the system highlights missing points and points with input overload. LMS Test.Lab Structures provides complete data annotation for maximum traceability. It stores the complete measurement setup with the measured results. Users can attach digital pictures of the setup details to the measured data, and add personal notes made during the test.

No barriers between acquisition and analysis

LMS Test.Lab Structures can run operational deflection shapes or modal analysis in parallel with the acquisition, providing preliminary modal results while the test is taking place. This helps validate data quality and creates valuable insight on the spot. Mode animation immediately reveals missing measurements, inverted sensor direction, an accelerometer that fell off, or incorrect calibration values. Preliminary mode shapes can show where additional measurement points are required for better resolution, or point to the need for different or additional excitation sites.

Time-saving advanced techniques

For large and complex structures with high damping and/or low response levels, traditional excitation techniques fail to inject sufficient energy into the structure and result in poor quality and noisy FRFs. In these cases, LMS Test.Lab MIMO Swept Sine Testing provides the high-level sinusoidal excitation and the high signal-to-noise ratio required to accurately measure these low response levels, together with the measurement speed of a broadband test.

LMS Test.Lab MIMO Stepped Sine Testing lets the front-end control the input force for multiple input and multiple output stepped sine excitation. By controlling the input forces, the MIMO stepped sine technique is perfectly suited for investigating nonlinearity and advanced structural characterization.

No compromises for the expert

Experts appreciate LMS Test.Lab Structures’ arsenal of state-of the-art parameter estimators that can solve even the toughest structural puzzles.

Least Squares Complex Exponential

Least Squares Complex Exponential (LSCE) is the standard (time-domain) pole-fitting method for both single and poly-referenced (MIMO) applications. LSCE is a proven algorithm that deals with a broad range of structures, providing required efficiency for high modal density.

LMS Test.Lab PolyMAX

The LMS Test.Lab PolyMAX modal parameter identification algorithm has revolutionized the modal analysis process for highly damped structures and tests with noisy data. Its outstanding stabilization properties result in a very straightforward modal identification. LMS Test.Lab PolyMAX is commonly used for operational as well as experimental modal analysis.

LMS Test.Lab Automatic Modal Parameter Selection

LMS Test.Lab Automatic Modal Parameter Selection (AMPS), an expert-level modal parameter selection tool, provides guidance for new users and speeds up the pole selection procedure on the stabilization diagram for complex structures. This tool is also used for operational as well as experimental modal analysis.

Advanced validation techniques

Advanced validation techniques include MAC (auto and cross), FRF synthesis and modal mass calculation, as well as stiffness and damping for physical correlations. Once a validated modal model is available, users can quickly try different modifications using simulation techniques. LMS Test.Lab takes the validation process a step further with smart suggestions for the best modification points. The online FRF synthesis of the modified structure really simplifies modification definition eliminating numerous iteration cycles.

Mastering masses of data

LMS Test.Lab Structures is designed to handle massive amounts of data effortlessly in case of large-scale structural tests and multi-test processes. The measurements as well as the analysis results are automatically assembled, making it easy to select the relevant data and to create a reliable modal model of the entire structure. Dedicated data management assures that input FRFs, processing parameters and analysis results remain properly related, minimizing the risk of subsequent misinterpretation.

Simulation-ready structural testing

Using test data to create and validate simulation models requires a broader scope of test parameters as well as a higher degree of consistency. LMS Test.Lab Structures is designed to master both challenges. It provides rotational degrees-of-freedom, rigid body modes and other realistic factors for the creation of an accurate dynamic simulation model. LMS Test.Lab Structures is designed to provide consistent modal sub-models. It offers tools to validate simulation models, including cross-MAC comparisons with experimental observations, orthogonality checks and comparison between computed-generated responses and actual physical shaker tests.

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