In my spare time I have been working on the next edition of the textbook. I was aware that the first edition was ‘incomplete’. In essence, every edition will be incomplete as there is always something more we can add. The First Edition was less comprehensive than I had hoped, but we had to release […]

This is a companion post to the first beam analysis post here.  These methods again reference the excellent  NASA-TM-X-73305 Structures Manual and cover the rest of the cantilever conditions and start on the single span beams: AA-SM-026-009 Free Engineering Spreadsheets: Beam Analysis – Cantilever – Moment at Free End AA-SM-026-010 Free Engineering Spreadsheets: Beam Analysis – Cantilever – […]

After a month restricted to limited release to the members of our mailing list we are now distributing our free structures engineering textbook to the rest of the world. This book is free for you, your friends and your colleagues to use without limitation. The book links to free spreadsheet methods and all references used within […]

In the course of developing a new a comprehensive set of section properties for common cross sections I started to look into the first moment of area of cross sections. This led me to calculating the shear stress distributions. Typically when an engineer is calculating shear stress in a cross section they calculate the average […]

In the final checking stage of the creation of our Design and Analysis textbook we have changed the structure of the book. The intent of this change is to use the content we have already created in a more comprehensive content structure. This should make the book more ‘future proof’. The book is created and distributed (for […]

It has been a few weeks since we posted any new analysis spreadsheets. We have been busy getting the check version of the engineering textbook ready for the mailing list subscribers which was finally released in the June newsletter. Along the way we did manage to create some analysis spreadsheets of the membrane analysis methods in […]

We had to design a set of belleville washers for a client last year so we had to go and find a useful design criteria. NASA came to the rescue this time. In (NASA TM X-73305, 1975) there is a simple method for sizing and behaviour of disc springs. The behaviour of disk springs is non linear […]

We have been working had to complete the buckling methods for the first official release of the text book. Because of the scope and depth in which we want to cover the subject we are going to limit the scope for the initial release of the book to initial buckling of flat panels, including looking at panel […]

Again, NACA provides a the solution to another problem. The theoretical derivation of plate compression buckling coefficients. I had a simple derivation, which uses this equation for the simply supported  plate buckling coefficient NACA-Report-733 has the expression that give the general curve for any edge restraint condition: The free spreadsheet is available here and has the simple expression […]

Yet again NACA shows what a remarkable set of work it really is. I am going through the buckling of isotropic design features for our Stress Analysis book. Almost every time I need a derivation from first principles or the mathematical basis for a set of design curves NACA does not disappoint. In this case I […]

One of the basic building blocks of any stress analysis is material data. It is one of the 3 basic parameters of material, geometry and loads that are required for a stress analysis. I wrote the first version of the spreadsheet 15 years ago and it has been updated and improved over time. It automatically […]

This post here looks at the a public domain method for the strength of potted inserts – However it is very important to note that the two main references for these methods are flawed in some way. This is the introduction from our (soon to be released for draft review) free engineering textbook: This chapter […]

As we go through the process of up loading all of our reference data to the library we can also complete uploading the linked and referenced spreadsheet methods. We have just uploaded our ECSS references so we have linked and uploaded our potted insert analysis spreadsheets. AA-SM-140 Composites – Potted Insert Strength – Key Parameters AA-SM-140-001 Composites – Potted Insert Strength […]

This is a follow on to the previous post of the FPL reports here. We have taken the derivation for the sandwich compression panel buckling coefficient and made it available in spreadsheet form. We have also started to upload our general set of sandwich analysis spreadsheets. These spreadsheets are numbered AA-SM-102-XXX and include AA-SM-102-001 – Composites – Cored Laminate Basic […]

You can read the first three posts in this series here: Post 1, Post 2, Post 3 There are limited options for dealing with a hole in a shear web. There is a often used ESDU reference for this situation. ESDU sheets are a commercial product and unless you, or your organization have paid for […]

You can read the first two posts in this series here: Post 1, Post 2 When you calculate a buckling allowable that is beyond the material shear yield stress the allowable is unrealistic. For shear buckling this can be particularly problematic as the shear yield strength is not typically given in the common material data set so […]

To refine the simple buckling analysis in the first post you can take account of the panel edge fixity and account for material non linearity. This post concerns how to take account of panel edge fixity. The method I prefer is defined in (NACA-TN-2661, 1952), this reference is the grand daddy of aircraft buckling source material. This paper […]

Writing the text book has been a good opportunity to go and re-examine the fundamentals of panel buckling analysis. Shear Buckling of a thin (elastic) panel is a good place to start. First of all, Terms: Why use the term elastic buckling? When you use Young’s Modulus to calculate the buckling allowable no allowance is […]

Brazing is not widely used in the aircraft industry. Recently we were asked to substantiate a number of brazed joints by one of our clients and that give us the opportunity to research this subject. This is a brief summary of the material from our soon to be released text book. The general opinion is that a brazed joint […]

Note added 1 March 2017: The Cozzone shape factor for common cross sections is now in the Section Properties of Common Cross Sections spreadsheet. There are expressions for many more cross sections. This subject is covered in depth in the new edition of our free textbook. This post can be considered obsolete. In writing the plastic bending […]