society news Reports of regional meetings Scottish region

The first meeting of the region for this session took place in Heriot-Watt University, Edinburgh, on the evening of 16 October. John Harris and Roger Easton of Guest International Ltd., staged a very informal Strain Gauge Workshop before an attendance of around 30. John demonstrated the quick and simple application of nitro-cellulose paper-backed foil gauges using nitro-cellulose cement, and many of the audience tried this technique and found it easy to master. Temperature limits were discussed and were generally agreed to be 60°C for paper-backed gauges, and 600°C for platinum-tungsten wire gauges with ceramic cement. This useful meeting concluded with a show of slides illustrating the Rokide flame spray method for applying high temperature gauges. A full-day star meeting on 'Dynamic Testing of Road Vehicles' was held on 20 November at the National Engineering Laboratory, East Kilbride. There were more than 50 participants, many of whom had come from the south. Three excellent speakers delivered illustrated talks on topics related to the theme, and the meeting included a general visit to the laboratories to see various working road simulation test rigs. Discussion was lively, with considerable controversy. Many organisations, in this country and abroad, undertake dynamic vehicle testing, and it became clear that there is far from general agreement as to how these test results should be interpreted in relation to service life. Indeed, it was not too clear exactly what constituted a 'test result' or what was considered to be the end-point of a test. Among lighter moments was one when a speaker, discussing descriptions of road surfaces in the USA, quoted the mysterious terms 'cow pasture' and 'chuck holes', and was somewhat uncertain what these meant. John Underwood, calling himself 'NEL's resident American', came to the rescue and described these road classifications in picturesque language to the amusement and enlightenment of the audience.

North East region

Because of the intervention of Harold Wilson the meeting arranged for 10 October had to be postponed until 24 October when Dave Mitchell and Peter Featherstone presented a paper 'Simulation of Operational Thermal Stresses in Generating Plant using Araldite Models'. The lively question-time which followed clearly demonstrated the interest aroused by the speakers in their experimental methods. The November meeting was held on the evening of the 14th at the International Research and Develop- ment Co. Ltd. laboratories where Leo McCalvey spoke on 'Development of Strain Gauge Calibration Rigs for British Standard and High Temperature Testing'. After a brief introduction in the lecture theatre the meeting moved to the laboratory where

the rigs were demonstrated and the necessary mod- ifications discussed. If any of the audience had doubts about the need for a British Standard before the meeting, these had been dispelled by the end.

Forthcoming regional meetings The following arrangements are announced, additional to information previously published :

Scott ish region The venue of the February half-day meeting, reported in the October Diary as Heriot-Watt University, has been changed to Strathclyde University. The meeting will be held there on the afternoon of 26 February when George Hartnup (Heriot-Watt) will give a talk on 'The use of mini-computers in experimental materials testing'. It is hoped to have other con- tributions from workers on similar problems. An additional meeting, to include the regional AGM, has been arranged for the afternoon of 23 April in Strathclyde University. The topic will be 'Residual stress measurement' and speakers will include John Underwood (NEL) and Peter Gawthorpe (Stress Engineering Services) who will discuss and demon- strate the hole-drilling technique.

North East region The full day star meeting with exhibition, scheduled for 9 April at Durham University, has provisionally been arranged to comprise talks by five speakers on the subject of 'Strain gauge instrumentation'. At the morning session on 'Basic instrumentation', Geoff Mordan (Welwyn), Roger Giles (Pye Unicam) and Peter Jackson (Fylde) will each speak to the topic, while in the afternoon C. B. Jolly (Parsons) and P. W. Bridge (Rolls-Royce, Derby) will discuss 'Telemetry applications'. Participants will have ample opportunity to view the exhibition and some time on the programme has been allocated solely to that purpose.

South West and Welsh region The January meeting on 'Photoelastic Coatings- Techniques and Methods', will be held on the afternoon of the 23rd, starting at 2.15 p.m. in the Rolls Royce Technical College, Bristol.

New Class 2 member A welcome is extended to

J. C. Bamford Research Ltd., Uttoxeter, Staffs.,

who have recently joined the Society as a Class 2 Corporate Member.

Eleventh annual conference- registration Arrangements for the Eleventh Annual Conference- joint with the Royal Institution of Naval Architects- are well under way. The Conference on 'Measurement

'Strain: January 1975 37

in the offshore industry', will take place from 8 to 11 September at Heriot-Watt University, Edinburgh. As stated in the advert in this issue, provisional registrations and reservations of copies of the Conference Proceedings will now be accepted by Mrs McCalvey. The limitation on the number of delegates is 250 and if this is oversubscribed, preference will be given to members of BSSM and RlNA who register before 31 March.

Moves by Dartec and Techni Measure Dartec Ltd., announce that they have now moved to the address :

Stourbridge Trading Estate, Mill Race Lane, Stourbridge, West Midlands. Tel : Stourbridge 77433.

Techni Measure announce their change of address to :

Dell House, Eastern Dene, Hazlemere, High Wycombe, Bucks. HP15 7BT Tel : High Wycombe (0494) 31 388.

Student subscription unchanged Attention is drawn to the fact that, although subscription rates for the other membershipcategories have increased, the rate for student membership remains unaltered at f 1.50 annually. The Society wishes to encourage increasing student membership and suggests that members in a position to do so, might bring the advantages of BSSM membership to the notice of students and young people working in the field. Student membership is open to undergraduates or any person under 21 serving an apprenticeship or attending a part-time or full-time course in engineering and having an active interest or participation in strain measurement. A student member enjoys the benefits of full membership, excluding only voting rights at general meetings, so he or she receives four quarterly issues of Strain, reduced rates for all Society meetings including the annual conference, and regular news letters and notices of regional and national meetings.

DD6 The attention of strain gauge users and manufacturers is drawn to the letter in this issue from Jim Mackinnon. This is an important matter on which users and manufacturers of gauges should express their opinions.

letter to the editor Dear Sir, I would like to use your columns to initiate a discussion on modifications to DD6, The Draft for Development on 'Methods of Calibration of Bonded Electrical Resistance Strain Gauges', which has been published for the last two years. As a member of the BSI Committee responsible for the document, and the contact for international discussion, most of my information has come from foreign sources. Dis- cussion has been central round the issue of strain gauge grading or classification and I quote some examples. Mr Dorsey of Micro-Measurements states: 'I believe there is a strong need for a universally accepted strain gauge "specification". The document I envisage would serve two main functions : (a) It would include accepted definitions for a broad

base of strain gauge terminology. NAS-942 is not far off the mark in this area.

(b) It would describe test conditions to determine various characteristics of strain gauges. In this vein it would delineate the needed environments, calibration assurances, and statistical treatment of data. Equipment known to have been useful in any of the tests included, could be described as references and guides. Conceivably, many devices might be suggested for any one test and might be accompanied by estimates of expected accuracy. Even suggested test procedures would not be out of order. ASTM E251 is written somewhat in this format.

There are a number of things that the proposed specification would not (and I think properly should not) include. Among these are : (a) Gauge grades. (b) Requirements for specific testing or information

supplied. (c) Specific test equipment dictation.' Mr Bergqvist of FFA Sweden, has expressed the opinion that subdivision of gauges into classes is extremely artificial and subjective, and should be deleted. However Professor Dr-lng Muller of Stuttgart University states that the German Committee are preparing an appendix to their standard in which they will define classifications for applications, e.g. strain gauges for common use and normal temperatures, or for high accuracy or elevated temperature measure- ments. I would like to ask the readers of Strain whether they wish a grading system for strain gauges, since, if this is not required, it would seem pointless for the British Committee to include it in a modified standard. It would be of considerable assistance to the com- mittee if both users and manufacturers would state their opinion on this important matter.

J. A. Mackinnon, 22 Division, National Engineering Laboratory, East Kilbride, Glasgow G75 OQU.

'Strain; January 1975 38