Strong Formulation Finite Element Method Based on Differential Quadrature: A Survey

This paper aims at investigating the effect of Carbon Nanotube (CNT) agglomeration on the free vibrations of laminated composite doubly-curved shells and panels reinforced by CNTs. The great performances of doubly-curved structures are joined with the excellent mechanical properties of CNTs. Several laminations schemes and various CNT exponential distributions along the thickness of the structures are considered. Thus, it is evident that the shell dynamic behavior can be affected by many parameters which characterize the reinforcing phase. A widespread parametric study is performed in order to show the natural frequency variation. The general theoretical model for shell structures is based on the so-called Carrera Unified Formulation (CUF) which allows to consider several Higher-order Shear Deformations Theories (HSDTs). In addition, a complete characterization of the mechanical properties of CNTs is presented. The governing equations for the free vibration analysis are solved numerically by means of the well-known Generalized Differential Quadrature (GDQ) method due to its accuracy, stability and reliability features.

Effect of agglomeration on the natural frequencies of functionally graded carbon nanotube-reinforced laminated composite doubly-curved shells

Stress and strain recovery for functionally graded free-form and doubly-curved sandwich shells using higher-order equivalent single layer theory

The theoretical framework of the present manuscript covers the dynamic analysis of doubly-curved shell structures using the generalized displacement field of the Carrera Unified Formulation (CUF), including the Zig-Zag (ZZ) effect given by the Murakami’s function. The partial differential system of equations is solved by using the Generalized Differential Quadrature (GDQ) method. This numerical approach has been proven to be accurate, reliable and stable in several engineering applications. The current paper focuses on Functionally Graded (FG) doubly-curved shells and panels using various higher-order equivalent single layer theories, introduced and applied for the first time by the authors to completely doubly-curved shell structures, and different through-the-thickness volume fraction distributions, such as four-parameter power law, Weibull and exponential distributions. Moreover, the classic theory of mixtures is compared to the Mori–Tanaka scheme for the calculation of the mechanical properties of the materials. In particular, the numerical applications presented in this work are related to particular FG configurations in which it is possible to model a soft-core structure using a continuous variation of the mechanical properties of the materials at hand. The natural frequencies and mode shapes of several structures are presented and compared to numerical solutions taken from the literature.

Free vibrations of free-form doubly-curved shells made of functionally graded materials using higher-order equivalent single layer theories

General higher-order shear deformation theories for the free vibration analysis of completely doubly-curved laminated shells and panels

Static analysis of functionally graded conical shells and panels using the generalized unconstrained third order theory coupled with the stress recovery

Numerical investigation of functionally graded cylindrical shells and panels using the generalized unconstrained third order theory coupled with the stress recovery

Generalized stress–strain recovery formulation applied to functionally graded spherical shells and panels under static loading

Static analysis of functionally graded conical shells based on an unconstrained third order theory

Soil rebuilding represents a major challenge in the recovery of abandoned quarries. In this study, we explored the possibility of using reconstructed Technosols, to achieve soil rebuilding goals at an abandoned quarry site. We first investigated the use of a mixture containing commercial manure and limestone debris (LD) as pedotechnomaterials for an “ad hoc” (re)constructed Technosol (CT), for the recovery of an opencast limestone quarry in one of most concentrated quarry areas in the world. In a field experiment, we tested and monitored different pedotechnosystems (PTSs) made up of constructed Technosol + pasture species + different Mediterranean plant species. Specifically, a control (CT, without any additional treatments) was compared to treatments with organic amendment (CTOA) and conventional fertilizers (CTCF). Data were collected over a 12-month period and included crop performance, plant nutritional state, soil physical-chemical parameters, and metabolites. Analysis of variance compared differences among treatments, while factor analysis (FA) interpreted multiple relationships while explaining observed variability. Results showed that CTOA had better soil physical-chemical properties, greater plant growth, and overall superior agronomic performances compared to all other treatments due to the improved substrate conditions. According to FA, these results appear related to the creation of fertile soil conditions, with most of the investigated metabolites (i) playing a pivotal role in observed outcomes, together with (ii) a clear potential in being considered as a reliable fingerprint for investigating plant responses in constructed PTSs. The proposed pedotechniques in CTOA development show a great potential for the full recovery of abandoned limestone quarries in degraded Mediterranean areas by providing an excellent medium for plant growth, facilitating environmental reclamation.

/pdf/constructed-technosols-as-a-soil-rebuilding-technique-to-13hepio0.pdf

Luigi Rossetti

Papers

Static analysis of functionally graded conical shells and panels using the generalized unconstrained third order theory coupled with the stress recovery

Numerical investigation of functionally graded cylindrical shells and panels using the generalized unconstrained third order theory coupled with the stress recovery

Generalized stress–strain recovery formulation applied to functionally graded spherical shells and panels under static loading

Static analysis of functionally graded conical shells based on an unconstrained third order theory

Constructed Technosols as a Soil Rebuilding Technique to Reclaim Abandoned Limestone Quarries in the Mediterranean Region: A Field Study