In today’s hectic world we are often required to make calculations quickly to work our way through technical problems. Before you start rummaging through distant college notes or dusty textbooks check the ExcelCalcs repository. It will get you off to a flying start and you'll pick up your ‘feel’ for a problem in minutes. ExcelCalcs is driven, in part, by my need for calculation tools for use in my work as a consultant mechanical engineer. The recent upload of Quick and Dirty Bolt Sizing Calculation.xls arises from a consultancy project I have just completed. The accompanying video helped me explain to my client how calculations and physical tests help us arrive at a satisfying solution.
Bolt Replacement Project – My client is a large multinational company operating fleets of railway vehicles. They regularly replace bolts in the vehicle transmission line. These bolts are precision-made, smooth running bolts supplied by a specialist manufacturer at a very high cost. As part of a value engineering exercise they approached MoreVision specifically for their technical expertise in bolting. Previously discussions quickly ground to a halt because nobody could be certain about the magnitude of loads applied to the bolt - so we proposed a strategy that required no knowledge of the bolt loading. We suggested using a standard bolt of the same grade but lubricated with a dry molybdenum-disulphide coating. In our workshop we tested a batch of the precision bolts by applying the tightening torque and measuring the bolt pretension using a load cell. We repeated the measurements for a batch of lubricated standard bolts and found that we required a lower tightening torque to achieve the same levels of pretension. Our detailed bolt calculations showed that whilst axial loads in the both bolts were the same, the torsional stress in the bolt shank was reduced in the lubricated standard bolt. This meant that, regardless of the applied load, the total stress in the replacement bolts would always be lower than the original precision bolt. Our client achieved a thirty fold reduction of cost over a whole fleet of railway vehicles which amounted to a multi-million dollar saving.
Learn how to size bolts so that they never come loose or break in service. How to select the correct tightening torque. Why you might consider a more accurate tightening method. Why you might choose to lubricate your bolt. How to increase the shear capacity of your joint. In the course of my engineering consultancy work the simple bolted joint presents all kinds of problems for engineers. There are different approaches to how they should be sized, depending upon the industry and background. In Quick and Dirty Bolt Sizing Calculation.xls I have minimised the number of inputs required to size a bolt to produce good joints quickly. Presentation of the results on a bolt chart will help you understand how bolts work and provides a visual indication when things go wrong. It makes a very useful bolt design guide.
Independent Design Assessment of Rollercoasters – You’ll be relieved to hear that all rollercoasters calculations are reviewed and scrutinised by an independent body. We pleased to be asked to review some calculations covering a new rollercoaster for one of the large theme park operators. It is good to sit on the other side of the table for a change but we are acutely aware that it is much easier to criticise than to produce. So where we disagree with an approach we provide sample calculations of what we believe is required. The sample calculations are, of course, taken from the ExcelCalcs repository. We also use our repository template solutions for risk assessment purposes – to determine the severity of the issue and the strength of our response. This approach allows us to produce a detailed response very quickly and is generally more constructive than simply criticising the submitted calculation documents. At MoreVision we also undertake independent design assessments of railway rolling stock, construction equipment, oil and gas plant and lifting equipment. Please contact me if you are interested in MoreVision consultancy services.
Introducing George Lungu
George Lungu's amazing rollercoaster animation generated using Excel scatter charts. Now I am pretty good with spreadsheets so it takes a very special spreadsheet to make me sit down open jawed and say wow. That’s just what happened when I first came across George’s work. George and I have since struck up a rapport and he has promised to send through more spreadsheets and offer the ExcelCalcs community an insight into the approach and techniques he uses. Watch this space…
A New Calculation from Spreadsheet King Alex Tomanovich
A "new" (well at least new from me) spreadsheet workbook on seismic analysis per the IBC 2006 / ASCE 7-05 Codes. Originally I thought (and hoped) that this was going to be a simple task of making a copy of the workbook for IBC 2003 and editing it as required. Well, the editing turned out to be fairly extensive, since as most of you know the IBC 2006 Code basically defers to ASCE 7-05. In this workbook IBC 2006 Code sections are only used up to the point of determining the Seismic Design Category (SDC). Beyond that point, the workbook uses the ASCE 7-05 Code. This workbook incorporates the changes provided in Supplement No. 2 to the ASCE 7-05 Code.
I'm sending out this update to the "IBC2003E.xls" workbook for seismic
analysis per the IBC 2003 / ASCE 7-02 Codes, for any of you who may
still be using this code version on some projects.
In the "Arch. Components" and "M & E Components" worksheets I added the calculation of the component vertical seismic force.