A prediction of bone remodeling thanks to a mechanical signal on cells - Predizione del rimodellamento osseo a partire da un segnale meccanico sulle cellule

This text wants to explore the process of bone remodeling. The idea supported is that the signal, the cells acquire and which suggest them to change in their architectural conformation, is the potential difference on the free boundaries surfaces of collagen fibers. These ones represent the bone in the nanoscale. This work has as subject a multiscale model. Lots of studies have been made to try to discover the relationship between a macroscopic external bone load and the cellular scale. The tree first simulations have been a longitudinal, a flexion and a transversal compression force on a full longitudinal fiber 0-0 sample. The results showed first the great difference between a fully longitudinal stress and a flexion stress. Secondly a decrease in the potential difference has been observed in the transversal force configuration, suggesting that such a signal could be taken as the one, who leads the bone remodeling. To also exclude that the obtained results was not to attribute to a piezoelectric collagen effect and not to a mechanical load, different coupling analyses have been developed. Such analyses show this effect is really less important than the one the mechanical load is responsible of. At this point the work had to explore how bone remodeling could develop. The analyses involved different geometry and fibers percentage. Moreover at the beginning the model was to manually implement. The author, after an initial improvement of it, provided to implement a standalone version thanks to integration between Comsol Multiphysic, Matlab and Excel.

Mechanical analysis and modeling of structural archetypes

This is a research B for the University of Bologna. The course is the civil engineering LAUREA MAGISTRALE at UNIBO. The main purpose of this research is to promote another way of explaining, analyzing and presenting some civil engineering aspects to the students worldwide by theory, modeling and photos. The basic idea is divided into three steps. The first one is to present and analyze the theoretical parts. So a detailed analysis of the theory combined with theorems, explanations, examples and exercises will cover this step. At the second, a model will make clear all these parts that were discussed in the theory by showing how the structures work or fail. The modeling is able to present the behavior of many elements, in scale which we use in the real structures. After these two steps an interesting exhibition of photos from the real world with comments will give the chance to the engineers to observe all these theoretical and modeling-laboratory staff in many different cases. For example many civil engineers in the world may know about the air pressure on the structures but many of them have never seen the extraordinary behavior of the bridge of Tacoma ‘dancing with the air’. At this point I would like to say that what I have done is not a book, but a research of how this ‘3 step’ presentation or explanation of some mechanical characteristics could be helpful. I know that my research is something different and new and in my opinion is very important because it helps students to go deeper in the science and also gives new ideas and inspirations. This way of teaching can be used at all lessons especially at the technical. Hope that one day all the books will adopt this kind of presentation.

Numerical evaluation of material model and thickness effect on LSP induced residual stresses

Laser Shock Peening (LSP) is a technological process used to improve mechanical properties in metallic components. When a short and intense laser pulse irradiates a metallic surface, high pressure plasma is generated on the treated surface; elasto-plastic waves, then, propagate inside the target and create plastic strain. This surface treatment induces a deep compressive residual stresses field on the treated area and through the thickness; such compressive residual stress is expected to increase the fatigue resistance, and reduce the detrimental effects of corrosion and stress corrosion cracking.

A 2-dimensional computational model to analyze the effects of cellular heterogeinity on cardiac pacemaking

The mechanical action of the heart is made possible in response to electrical events that involve the cardiac cells, a property that classifies the heart tissue between the excitable tissues. At the cellular level, the electrical event is the signal that triggers the mechanical contraction, inducing a transient increase in intracellular calcium which, in turn, carries the message of contraction to the contractile proteins of the cell. The primary goal of my project was to implement in CUDA (Compute Unified Device Architecture, an hardware architecture for parallel processing created by NVIDIA) a tissue model of the rabbit sinoatrial node to evaluate the heterogeneity of its structure and how that variability influences the behavior of the cells. In particular, each cell has an intrinsic discharge frequency, thus different from that of every other cell of the tissue and it is interesting to study the process of synchronization of the cells and look at the value of the last discharge frequency if they synchronized.