SIMULATION  AND  PREDICTIVE  ANALYSIS

   PROTOS is a strong advocate for the timely and systematic use of a Simulation / Analysis, Test and Model Correlation/Updating strategy to aid and guide the complex tasks from initial Engineering Design to final product Qualification and Manufacturing.

 Once dimensioned documentation of candidate Design versions is available PROTOS can embark on the Simulation and Predictive Analysis tasks.

Initially the Mechanical ( Static, Dynamic, Acoustic,..) Thermal and other in-Service Environments to which the product will be exposed are identified and their mathematical representations are defined.

The inherent mechanical or thermal characteristics of the Design versions are then simulated by the construction of appropriate (Static, Dynamic, Acoustic, Thermal, etc..) mathematical models.

The way the distinct Design versions will respond to In-Service Environments and whether they will maintain their functionality and integrity are predicted by the various types of Analyses performed. These analyses include the application of  the Simulated Environments on the Mathematical Model representations of the Design version.

        Once the Models are validated, via the Test and Correlation/Updating process, they can be employed as Virtual Prototypes that are used to perform the so called "What if studies". These studies are very  effective Design Change Assessment procedures that are used to guide the Design process in Optimising the product to meet all its objectives i.e. Functionality, Robustness, Strength, Stiffness,   Efficiency, Cost, Manufacturability etc..

        The systematic Simulation/Analysis, Test, Model Correlation/Updating and consequent  use of the validated Models Optimises the product while at the same time reduces its time-to-market (by going through a much smaller number of design iterations, prototypes and  tests performed in the Design cycle).

 PROTOS has the expertise to help their clients in this crucial stage of Product Development by offering their Consulting Services in the complete range of Simulations and Analyses works to be performed.

        Static Analysis

 PROTOS are using commercial state of the art Software     ( IDEAS, PATRAN/NASTRAN, ANSYS, etc..) for the construction, verification, solution and visualisation of the Finite Element Models ( FEMs ) and their  results for the Simulation of the physics and the derivation of Static environment related predictions. Analyses results can be obtained for Strength, Stiffness and Rupture studies as part of initial Design assessment exercises or to serve as predictions of the product's Static Test Qualification campaign during the more advanced stages in the products developments cycle. Detailed Stress calculations can also be performed using traditional Design Handbooks as well as in-house developed procedures.

        Dynamic Analysis

 PROTOS have extensive experience in Finite Element Modeling and studying the structural behaviour of a product when under the influence of a Dynamic Environment. It is a known fact that the majority of structures are exposed to such an environment (transient, sinusoidal, random, mechanical shock, acoustic loading, etc...) during some stage of their In-Service life. PROTOS are using commercial state of the art Software (IDEAS, PATRAN/NASTRAN, ADAMS, RAYON, ANSYS etc..) in order to calculate the dynamic loads and responses due to dynamic inputs. Both Linear and Non-Linear phenomena are simulated and corresponding solvers of IDEAS, NASTRAN, and ABAQUS are employed in prediction calculations. Appropriate standard specifications (MIL-STD, ESA, etc...) are used according to the product under consideration.

        Case Study

• Model Reduction/Test Analysis Model (TAM)

        Structural complexity, light weight/flexible structures, extended frequency ranges, etc call for more and more refined Finite Element models with, sometimes, tens of thousands of degrees of freedom. Practical uses of these models (cpu run time, data processing, inclusion in system models, etc...) however are seriously hindered by their shear size. An equivalent reduction (predicted dynamics of the reduced model are the same as those of the original) of the size (order) of these large models therefore is a very useful tool in performing Dynamic Analysis and predictions for the Design Qualifications of structures.

        The definition of the measurement plan is one of the key factor in the success of a Modal Test. The use of engineering judgment could lead in the selection of an inadequate number of measurement points on the measured structure, missing thus manifestations of modal response that would compromise the success of  the test. The production of the so called Test Analysis Model (TAM) is an objective and accurate way of defining the minimum number of measurement points/directions and their distribution on the structure that will capture all the modal manifestations of the modes requested. TAM is effectively another equivalent reduction of the modal order, down to the minimum number of degrees of freedom that will have to be measured in the test.

        PROTOS has extensive expertise in Model Reduction and has been one of the leading advocates for the use of TAMS in Modal Testing preparation. Standard (Guyan, IRS, SEREP, Modal, etc...) and in-house produced procedures are used in the derivation and checking of equivalent reduced Dynamic Models.

• Model Correlation/Updating

        Simulation and Predictive Analysis are very useful, well developed tools that provide objective, quantitative assessment of a Design's feasibility and overall performance. The quality and precision of Predictive Analysis however depends on the fidelity of the Finite Element models used in Simulations. Despite the recent advances in computing capacity and modeling software, Finite Element models contain errors in their Simulation precision. These errors are not necessarily due to the modeling expertise or approach but mainly due to uncertainties on mechanical properties, boundary conditions at interfaces, damping capacities, errors in data input to the models etc.. .

        One of the purposes of Modal Test is to provide measurements that can be used to check and correct, if need be, the precision of the Finite Element Model. The process of comparing Finite Model predictions with the Modal Test results is called Model Correlation and the consequent operation of changing the Model so that its predictions much the actual measurements is called Model Updating. Model Updating based on "trial and error" procedures, especially when they are preceded by quantitative subjective Correlation conclusions are very time and resource consuming and very rarely identify the true errors on the model.

        PROTOS are one of the leading companies in the application of mathematical, objective and rapid techniques for the Updating of Finite Element Models based on the results of a Modal Test. The methods are based on Design Sensitivity Analysis results and their use in Constrained Optimisation procedures. These procedures aim to minimise the error or the difference between predicted and measured data by operating on the Sensitivity of these data to small changes in some questionable properties or parameter values of the Model. The in-house developed procedures of PROTOS make use of the Test Analysis Model (TAM) produced at the pre-test stage as well as commercial Software, namely FEMTOOLS developed by DDS

Satellite Antena FEM Modeling

Satellite Antena Modal Test

Satellite Antena Modal Test Result

Satellite Antena FEM / Modal Test

Correlation and

Model Updating Studies