Structural Optimisation: Biomechanics of the Femur

A preliminary iterative 3D meso-scale structural model of the femur was developed, in which bar and shell elements were used to represent trabecular and cortical bone respectively. The cross-sectional areas of the bar elements and the thickness values of the shell elements were adjusted over successive iterations of the model based on a target strain stimulus, resulting in an optimised construct. The predicted trabecular architecture, and cortical thickness distribution showed good agreement with clinical observations, based on the application of a single leg stance load case during gait. The benefit of using a meso-scale structural approach in comparison to micro or macro-scale continuum approaches to predictive bone modelling was achievement of the symbiotic goals of computational efficiency and structural description of the femur.Comment: Accepted by Engineering and Computational Mechanics (Proceedings of the ICE

Femoral bone mesoscale structural architecture prediction using musculoskeletal and finite element modelling

Through much of the anatomical and clinical literature bone is studied with a focus on its structural architecture, while it is rare for bone to be modelled using a structural mechanics as opposed to a continuum mechanics approach in the engineering literature. A novel mesoscale structural model of the femur is presented in which truss and shell elements are used to represent trabecular and cortical bone, respectively. Structural optimisation using a strain-based bone adaptation algorithm is incorporated within a musculoskeletal and finite element modelling framework to predict the structure of the femur subjected to two loading scenarios; a single load case corresponding to the frame of maximum hip joint contact force during walking and a full loading regime consisting of multiple load cases from five activities of daily living. The use of the full loading regime compared to the single load case has a profound influence on the predicted trabecular and cortical structure throughout the femur, with dramatic volume increases in the femoral shaft and the distal femur, and regional increases at the femoral neck and greater trochanter in the proximal femur. The mesoscale structural model subjected to the full loading regime shows agreement with the observed structural architecture of the femur while the structural approach has potential application in bone fracture prediction, prevention and treatment. The mesoscale structural approach achieves the synergistic goals of computational efficiency similar to a macroscale continuum approach and a resolution nearing that of a microscale continuum approach

Spatial surface-pattern analyses and boundary detection techniques applied in forest ecology

[EN] We review methods for uni- and multivariate surface pattern analysis and boundary detection used in forest ecology. A continuous surface pattern is defined as the locations of points (trees) in the space and the associated variable or variables. We illustrate useful methods to describe spatial patterns and infer the generating processes. We show the statistical basis and applied examples of univariate methods for binary (join counts) and quantitative variables (Moran and Geary correlograms, semivariograms, fractal dimension). We explain the calculus and interpretation of multivariate methods to describe surface patterns (Mantel test and correlogram) and their relationships with ordination methods. Finally, we show examples of techniques for boundary detection. Most analysed patterns corresponded to Pinus uncinata forests from the upper altitudinal limit in the Pyrenees or from a relict population. We discuss the advantages and disadvantages of each methodology and their applications in forest ecology.[ES] En este trabajo se revisan los métodos de análisis univariable y multivariable de los patrones de superficies y de detección de fronteras más utilizados en ecología forestal. El patrón de superficies es un patrón espacial continuo definido por las posiciones de los puntos (árboles) en el espacio y una o varias variables asociadas a cada punto. Se ilustran métodos útiles para describir patrones espaciales e inferir los procesos que los generaron. Se muestra el fundamento estadístico y ejemplos aplicados de métodos de análisis univariables para variables binarias (conteo contiguo) y cuantitativas (correlogramas de Moran y Geary, semivariogramas, dimensión fractal). Se detalla el cálculo e interpretación de métodos multivariables para la descripción de patrones de superficies (correlograma y test de Mantel) y su relación con los métodos de ordenación. Finalmente, se muestran ejemplos de métodos para la detección de fronteras. La mayor parte de los patrones reales analizados provienen de bosques de Pinus uncinata del límite altitudinal superior en los Pirineos o bien de una población relíctica. Se discuten las ventajas y desventajas de cada metodología y sus aplicaciones en ecología forestal.Los datos de Vinuesa se obtuvieron en el proyecto AMB95-0160 (CICyT).Peer reviewe

Design and analysis of cross vaults along history

The history of cross vaults began almost 2,000 years ago with a widespread use during the Middle Ages and Renaissance, becoming nowadays one of the most diffused and fascinating structural typologies of the European building cultural heritage. However, conversely to the undeniable excellence achieved by the ancient masons, the structural behavior of these elements is still at the center of the scientific debate. In this regard, with the aim of reviewing the knowledge on this subject as a concise and valuable support for researchers involved in conservation of historical buildings, with a focus on design rules and structural analysis, the present study firstly introduces the cross vaults from a historical perspective, by describing the evolution of the main geometrical shapes together with basic practical rules used to size them. Then, the article deals with the subsequent advancements in structural analysis methods of vaults, until the development of modern limit analysis.This work was partially carried out under the program "Dipartimento di Protezione Civile - Consorzio RELUIS", signed on 2013-12-27.info:eu-repo/semantics/publishedVersio

Modelling with forces: grammar-based graphic statics for diverse architectural structures

Most architectural modelling software provides the user with geometric freedom in absence of performance, while most engineering software mandates pre-determined forms before it can perform any numerical analysis. This trial-and-error process is not only time intensive, but it also hinders free exploration beyond standard designs. This paper proposes a new structural design methodology that integrates the generative (architectural) and the analytical (engineering) procedures into a simultaneous design process, by combining shape grammars and graphic statics. Design tests presented will demonstrate the applicability of this new methodology to various engineering design problems, and demonstrate how the user can explore diverse and unexpected structural alternatives to conventional solutions

From graphics for calculations to drawings for works. Exercises of students engineers of the Regia Scuola di Applicazione di Torino at the end of the nineteenth century Dalla grafica per calcolare ai disegni per costruire. Esercizi di allievi ingegneri della Regia Scuola di Applicazione di Torino di fine Ottocento

Graphic representation can be a tool for analysis and synthesis that closely relates different areas of scientific knowledge. Among these, the Graphic Statics is a discipline that uses graphic techniques to solve the problems of the equilibrium of a rigid body, allowing to reach the definition through the composition or the decomposition of the forces represented in a conventional way. Specific geometrical methods are used to determine the tensions and pressures in structures, including complex ones, which are subjected to internal and external force systems. The contribution intends to present some didactic materials, also describing the historical and cultural context in which they matured, coming from the heritage preserved at the Politecnico di Torino relating to the graphic elaborations drawn by the students of the Reale Scuola di Applicazione at the end of the nineteenth century. These graphic illustrations show the ability of graphic calculation aimed to the study of the relationships between the geometry of the structure and the forces acting, associated with the art of the “buon disegno”