Chairman: David Richards, SEE
Deputy Chairman: Thomas Trost, SEES
The aim of the CEEES Technical Advisory Board for Mechanical Environments (TABME) is to advance methodologies and technologies for quantifying, describing and simulating mechanical environmental conditions experienced by equipment during its life cycle.
The TABME acts as a forum for European collaboration and interaction for the generation of national and international standards related to mechanical environmental testing, establishing the environmental severities as well as the derivation of test severities from actual environmental conditions. The TABME performs this role under the heading Systematisation of Measurement Methodologies.
In addition to the above the TABME has acted as a co-ordinator for European round robin exercises undertaken with the aim of improving the techniques and methodologies used within Europe to quantify mechanical severities. For the same reasons the TABME has championed novel methodologies.
The CEEES Technical Advisory Board for Mechanical Environments was previously known as the CEEES Transportation Stresses Working Group (TSWG).
The results from two round robin exercises, undertaken under the auspices of the TABME, are included here.
The first round robin exercises arose from a survey initiated in 1989. That survey polled some 33 European agencies and found that no general consensus existed as to how improved road transportation test severities could be derived. A round robin exercise was suggested as one method by which the range of methodologies in use could be determined.
The main aim of the first round robin exercise was to identify the range of methods used for the assessment of road transportation dynamic data. However, the round robin exercise was also intended to quantify any variations arising from the use of different methodologies. The intent was that each participant should utilise what ever method they considered appropriate. To this end the requirements for active participation were set so as not to influence the participant's choice of approach. In practice this meant imposing relatively few constraints. As a consequence some limitations arose in the quantitative comparisons.
The second round robin exercise was intended to address a specific aspect identified as a concern in the first exercise. One of the surprising findings of the first exercise was the variations in methods the participants used to identify and quantify shocks from within the background vibration. This variation was reflected in a poor success rate at identifying and quantify the shocks. The late Karl-Heinz Hansen of the Gesellschaft fur Umweltsimulation (GUS) proposed an exercise to both specifically investigate this aspect and as a vehicle for improving vibration analysis skills.
The proposed aims and objectives of the second exercise were;
i. To evaluate the methods in current use to recognise and quantify shocks when embedded in vibration of the type expected from the transportation environment.
ii. To quantify the variations arising from the use of different methodologies. In particular to identify the degree of operator experience and skill required for the different methods.
iii. To generate progressively more difficult test cases against which experience and skill can be improved.
A Round Robin Exercise On Road Transportation Data Download >>>
Two Round Robin Exercises On Road Transportation Data Download >>>
The aim of the EC funded SRETS (Source Reduction by European Testing Schedules) project was to gather data from a number of sources and a wide range of packed products being transported throughout Europe. The collected data formed the basis for setting up state-of-the-art in Europe for test methods and test schedules of packages and products. The derived severities formed the basis for a CEN standard. The final report from the SRETS work is included here.
It was the aim of the SRETS project to complete the existing standards concerning the testing of package through the "random vibration" test. Furthermore should a test schedule be made.
Partial aims of the project were:
SRETS (Source Reduction by European Testing Schedules) was supported by the EC (European Commission) Standards, Measurements and Testing Programme (SM&T). Subordinated to Contract No SMT4-CT95-2005, SRETS was project No 2109. Co-ordinator of the SRETS project was Dr.-Ing. Ulrich Braunmiller, Fraunhofer ICT, Pfinztal, Germany.
All of the project partners contributed to the content of this report;
Source Reduction by European Testing Schedules Download >>>
IEC documents 60068 & 60721 are the responsibility of IEC Technical committee (TC) 104. It was formed in 1997, from the merger of IEC TC 50 (responsible for 60068) and IEC TC 75 (responsible for 60721). The merger was intended to ensure alignment of information in IEC 60068 & IEC 60721. Whilst, TC 104 initiated a short term work around to attempt to rationalise test severities between the standards, it did not correct the underlying problem. To update the content of 60721 Working Groups 14 & 15 were set up. The objective of these groups was to collect field data and to collate the validated data into a form suitable for comparison with IEC 60721.
The three documents attached are draft collections of data for transportation of equipment by fixed wing jet aircraft, by wheeled road vehicles and by rail. The data validation process used is set out in the annex of each document. The purpose of these reports is to allow comment and for the basis for additional data.
A Plea to Potential Contributors of Data. Working Group 14 (Climatic Conditions) and Working Group 15 (Dynamic Conditions) request that you contribute reduced data to be used for the improvement of IEC 60721-3.
Ideally data should include a description of the application / situation and if possible, a description of the data collection methodology as well as a description of the data analysis process.
Advantages to contributors of data include;
The vibration analysis tools known as Maximum Response Spectra (MRS) and Fatigue Damage Spectra (FDS) were originally developed within the French Atomic Energy Authority. Over the years the CEEES TABME has acted as a forum for dissemination of techniques and applications associated with MRS & FDS.
Two papers are included here;
The first paper uses MRS and FDS to compare the damage effects of different test severities for transportation. Although the original intent was a comparison between different severities with the UK Defence Standard Def Stan 00-35, it includes a number of other test severities from other standards.
The second paper sets out an exercise involving the acquisition of automotive vibration data and the conversion of this, using MRS and FDS, into a test severity for automotive applications.
The original purpose was as a means of comparing the affects of different vibration environments on equipment. The different vibration environments were compared in terms of their damage potential effects on notional components within the equipment. The normal damage effects addressed were peak acceleration response relating to internal loadings, (by means of Maximum Response Spectra) and fatigue (by means of Fatigue Damage Spectra). However, consideration of absolute and relative displacement is also possible to ensure motions do not exceed the available dynamic spatial envelope.
The French Atomic Energy Authority published their work on MRS and FDS in the mid 1970's and papers on the subject were published in France, the UK and the US. Unfortunately, because the method required a lot of computing and specialist computer programming, it was not extensively taken up at that time. To alleviate the computational problems the originator of the method produced solutions specific to random vibration and sine sweeps. By making a number assumptions very significant improvements in computing time could be made. However, the necessary assumptions for random vibration and sine sweeps are different. In consequence, there was always a doubt that any differences may originate from the different assumptions rather than the environment. To encourage wider use of MDS and FDS the originator also produced public domain computer programs, such as DEGAT, able to run on PC's.
In recent years the capabilities, have become readily available, to undertake the extensive computing required by MRS and FDS. In addition the use of MRD and FDS as a quantitative basis for setting test severities has been shown to be practicable. The advantage of using MRD and FDS as a quantitative basis for setting vibration test severities is that they can be used to set a traceable severity in terms of both vibration amplitude and test duration. This has been taken up by the French MOD who have embedded the procedure into GAM EG 13. Moreover, the process has received substantial EU research funds and is now a commercially available product.
Paper on Comparison of Test Severities Using FDS Download >>>
Paper on the Derivation of Test Severities Using FDS Download >>>
The European Commission has mandated the European Standardisation Organisation CEN to screen and to compare the existing national and international standards related to defence procurement and to give recommendations for preferred application in future.
CEN BT 125 has initiated a CEN Workshop (WS 10) to create a European defence procurement standardisation handbook. As a first activity, a number of European national Ministries for Defence have described their national procurement process and have compiled a database of widely adopted standards used in this procurement process. As a next step eight priority areas were identified for more detailed review by expert groups. The task of these groups was to compare the technical content of various standards with the aim of recommending a reference for European defence procurement. The Final report f CEN WS 10 Expert Group 8 is included here.
One of these priority areas was to review available environmental engineering standards including the appropriate environmental testing standards and the environmental program management standards. The appointed expert group (EG 8), mainly comprising of experts of the European umbrella organisation of the societies for environmental engineering CEEES, took over responsibility at the beginning of 2004. The group had a mix of representation from European national Ministries for Defence as well as European Industry. Many of the experts were also active in national or international standards committees. One reason for the strong support of Expert Group 8 was that for the first time in the history of standardisation of environmental engineering a broad comparison survey was been mandated.
Report of Expert Group 8 Environmental Engineering Download >>>
The CEEES Technical Advisory Board for Mechanical Environments has assembled a guidance document reviewing methodologies for deriving vibration test severities from measured data.
The methods encompassed include; the traditional enveloping methods and derivatives, two different methods used to derive severities included in Mil Std 810, the use of amplitude probability distributions as well as the two response based methods - Fatigue Damage Spectra and Maximum Response Spectra.
For each of the six different methods the paper describes the calculation process that is normally adopted and this is supported by an example. To aid the user in the selection of an appropriate method the paper sets out the assumptions and limitations of each method as well as the advantages and disadvantages. As further guide it also indicates the repeatability and traceability of each method along with uncertainty factors that may be introduced. Lastly for each method the paper indicates the technical relationship with other methods.
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