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1️⃣ The first picture is a an example of Topology Optimization applied to an hypotethical Upright of an electric sport car, that I was showing to my students. It considers only four load cases: Bump, Acceleration, Braking and Outer Cornering. Those are anyway enough to show how such a component has to withstand to forces that […]

💡 Each time I think about what could better represent the idea of 𝐌𝐞𝐜𝐡𝐚𝐧𝐢𝐜𝐚𝐥 𝐄𝐧𝐠𝐢𝐧𝐞𝐞𝐫𝐢𝐧𝐠, well, 𝐠𝐞𝐚𝐫𝐬 always jump into my mind 😬 🔦 The example in the animation is a 𝐧𝐨𝐧 𝐥𝐢𝐧𝐞𝐚𝐫 𝐝𝐲𝐧𝐚𝐦𝐢𝐜 𝐭𝐫𝐚𝐧𝐬𝐢𝐞𝐧𝐭 𝐚𝐧𝐚𝐥𝐲𝐬𝐢𝐬, solved with the implicit approach. The non linearity is coming from both the 𝐥𝐚𝐫𝐠𝐞 𝐝𝐢𝐬𝐩𝐥𝐚𝐜𝐞𝐦𝐞𝐧𝐭 and the 𝐜𝐨𝐧𝐭𝐚𝐜𝐭 between […]

📌 In the last days I have been faced with what is commonly called “linear contact”. 🔨 Which is an oxymoron . 🛠️ Because contacts can open, close, slip or stick. And they can change from one state to another one during the analysis, forcing the stiffness matrix [K] to be regenarated, typical situation of […]

Imagine this scenario: we have built a huge model, that has contacts and even some parts that can undergo plasticity and we have therefore also used a non linear material model for those parts. The calculation took few hours, so we have run it over night, we got the results, we checked them and then, […]

Verifying the structural integrity of mechanical components is a critical step in the design cycle, particularly for parts that must withstand loads.  The concurrent demand for reduced production costs and timelines, while simultaneously improving quality, necessitates the use of advanced design techniques like “Virtual Prototyping.” Finite Element Models allow for a virtual representation of an […]

It might happen that new starters in Structural Analysis based on Finite Element Models tend to get confused by what is a Load Case with what is a Load Step. The Load Case is used in linear static analyses and it is composed by a set of forces, moments, pressures, temperature distributions and boundary conditions. […]

Nice speech to an interested audience. Here is the video  

Because we touched the topic in two occasions on these pages (Post Buckling Analysis of a Frame and The Buckling Analysis and Test of a PushRod for a Race Car Suspension) we come back on it  with this article, trying to give more insights on the instability of structures. To make things more understandable, we […]

The double wishbone suspension system is one of the most used in racing cars and among some possible different schemes, the one that uses a PushRod to activate the elastic and damping elements (just to mention a few) is probably the most “standard” approach. As the word itself suggests, the PushRod is a rod that […]

The Gyroscope is a quite fascinating piece of mechanics, though very simple, and for sure everyone  in their life has at least once seen and even played with one. The part is simple, but the phisics behind it is not so intuitive; we are not going to enter into the equations that gouverne the behaviour […]

Knowing the material limits in terms of structural strength is paramount to assess if a given structure can withstand the loads for which it is designed, and which reserve it has to allow for unexpected higher loads. If for ductile materials this process is very well consolidated and generally based on the Von Mises stress […]

Historically, fatigue tests are performed by rotating bending, i.e. cylindrical specimens are rotated while a load stresses them with a fixed direction in time: this way an alternating cycle from zero is easily obtained. Generally the specimens have a rather small diameter (maximum 10 mm) and it was discovered that, for specimens of larger size, […]

This example is taken from the book Computational Structural Engineering We have the planar frame shown in figure 11.22 through the related beam-type finite element model. From a first linear buckling analysis we find that Fcr = 10512 N. Clearly the element that becomes unstable is the diagonal A, as we can see from figure […]

Every now and then every Structural Engineer has to asses fasteners against thread ripping, especially when non standard screws are used. In fact, in general, handbooks give the tightening torque for every nominal diameter and the load that the bolt can whithstand, assuming that both the screw and the nutscrew are made of steel. In […]

This simulation was done more for fun rather than being really useful to some design activity. Nonetheless it shows how powerful simulations can be. In this case the material properties used to simulate the tensile test shown in a previous news are here implemented into a Charpy Test coupon (U-shape notch) and the simulation is […]

Introducing the plastic behaviour of a material in a Finite Element Model is not straightforward, but it is not impossible. In the book “Computational Structural Engineering” at Chapter 13 many hints and tips&tricks are given to succesfully introduce into the model the required material data, from a bilinear (simpler) behaviour up to the full stress-strain […]

In general to discriminate if a composite structure can withstand the loads to which it has been designed, the first ply failure approach is followed; this means that when a ply in the laminate reaches its failure point, i.e. has a Failure Index equal to 1.0, then the whole structure is considered failed. Fibers, especially […]

In general the application of a preload inside a member in a Finite Element Model is done by the code by applying MPC equations to the nodes laying on the surface where the preload is to be applied; for example in a bolt modelled with solid elements, the shank will be split at the surface […]

At the times when low computational power and low memory capacity were available, the Superelement technique (more precisely defined as “substructuring“) was used to solve models with a high number of DOFs, while still staying within the limits imposed by the hardware. The method consists in dividing the complete structure to be analysed into substructures; […]

As well known, it is generally a good practice, in a finite element analysis, to perform several iterations of calculation of the same structure in order to determine what is the best mesh density to obtain reliable results. In our days the necessity to try and reduce the commitment of the calculation resources is less […]

I think I am not exaggerating if I say that worldwide the FEA community recognizes that the “best” element type for 3D structures is the hexahedron element (the so-called brick element), especially in its linear formulation (linear shape functions – 8 nodes per element), where with “best” I mean the optimal compromise between model size […]

My generation of Structural Engineers (graduated in the early ’90s of last century) in the mechanical field were post-pioneers in computation with Finite Elements. I say this because they found themselves operating in an industrial environment that was not at all ready to include in the design cycle a phase whose usefulness entrepreneurs struggled to […]

Fatigue assessments are never an easy task, but they are not impossible. FE results on one side give a bunch of information that might confuse and on the other pose questions on both the notch sensitivity and dimensional coefficients. In Chapter 10 of the book “Computational Structural Engineering” the reader is guided through all those […]

In Chapter 17 of the book “Computational Structural Engineering” a very deep analysis of a “simple” bolted connection is presented: influence of preload and friction are discussed and failure is simulated. Finally, a comparison between the implicit and explicit approaches (which are discussed in Chapter 14) is also presented.https://www.cgcae.com/wp-content/uploads/2024/10/Boltfailure.mp4

Here is one case where axisymmetric elements can give great results in very short times, even when dealing with hyperelastic materials! In this case an O-Ring is stretched into its position (this phase is not reported here, but maybe in a future post it will) and then the outer tube is pushed to assemble the […]