Experimental Behavior of a Full-Scale Housing Section Built with Cold-Formed Steel Shear Wall Panels under Horizontal Monotonic and Cyclic Loading

This paper presents the results of an experimental study on the behavior of the cold- formed steel shear wall panel (CFSSWP) with fibrocement panels as sheathing, when it is subjected in-plane shear deformations and flexural deformation under perpendicular monotonically increasing horizontal loads on the longest plane. A full-scale housing section was built with three walls and a ceiling using commonly used construction details in El Salvador. The strength and stiffness of the experimental specimen tested overcame significantly critical demand imposed by the technical design standards in this country. Additionally, a simplified finite element model was defined with the objective to analyze stresses in the components. The results of the numerical model were similar to the experimental model tested.

A Component-Based Model for Novel Modular Connections with Inbuild Component

A modular steel structure building has obvious advantages in reducing construction period and protecting the environment due to its unique construction method, so it is widely used in modern construction. However, the modular building connection design and modeling are mostly based on the traditional connection research results. To address this issue, the paper developed a component-based model for novel modular connections with an inbuild component. First of all, the comprehensive parameter study was implemented using elaborate finite element models. Then the component-based model for novel modular connections was developed, and the force-deformation response of each component was determined using the finite element method. Thirdly, assembly of all components to overall rotational joint and the simplified finite element model of modular connections was obtained. Finally, comparison between simplified and refined finite element was conducted, the results showed that the proposed model can predict the mechanical behavior of modular building connections within the acceptable margin of error.

Multi-Objective Structural Optimization of Vehicle Wheels

This work focuses on the development of an innovative design methodology for lightweight wheels of road vehicles. In particular, the activity is carried out for the specific case of a wheel designed for an ultra-efficient vehicle for Shell Eco-marathon competition, with the aim of finding preliminary design solutions. A simplified finite element model of the tire structure is employed for an accurate modelling of the forces acting at the tire/rim interface. The material properties of the tire structure are identified by means of experimental tests. The computed tire/rim force distribution is applied to the rim exploiting a simplified finite element model of the wheel rim. A multi-objective optimization problem is formulated, based on mass and compliance minimization. Several wheel design layouts are investigated, which differ in terms of number of spokes (i.e. 3, 5 and 7), spokes layout (i.e. straight and Y-shape) and spokes cross section (i.e. rectangular, C and I). Geometric quantities related to the cross section dimensions of the spokes and to the rim thickness are optimized. Design constraints related to structural stiffness and elastic stability (both global and local buckling) are taken into account. The developed finite-element based model of the wheel is used to train a set of neural networks to approximate the objective functions and the design constraints to reduce the computational effort. A multi-objective genetic algorithm is adopted to obtain the Pareto-optimal solutions. The implemented method has proved to be a valuable tool to support design engineers in taking critical decisions in the early stages of the design process.

A Simplified Finite Element Model of Riveted Joints for Structural Analyses with Consideration of Nonlinear Load-Transfer Characteristics

A simplified finite element model of riveted joints for structural analyses which effectively incorporates nonlinear response of riveted joints is proposed. Load-transfer characteristics of riveted joints were experimentally and numerically studied. First, a detailed finite element analysis for the process of a tensile test of a single-row joint which consists of squeezing of the rivet and tensile loading to the joint was conducted to confirm the validity of a conventional method of analysis. The load–relative displacement behaviors of single-row joints observed in the detailed finite element analysis and previously conducted experiments agreed well. Then, a simplified method of the analysis was developed based on the detailed analysis and the experiments and was applied to analyses of multiple-row joints. A nonlinear relationship between load and relative displacement in the simplified analyses had good agreement with the detailed one. Distributed loads to the multiple rivets in the simplified analysis coincided with those of the detailed analysis under the maximum load. Memory and CPU time required to run the simplified analyses were reduced to about 1/4 and 1/6 compared to those of the detailed analysis, respectively.

Simulation and Experimental Validation of Sound Field in a Rotating Tire Cavity Arising from Acoustic Cavity Resonance

As we all know, the tire acoustic cavity resonance noise (TACRN) can cause irritating noise in a vehicle, but it is evidently difficult to be weakened. To obtain accurately the characteristics of TACRN is a key step of attenuating TACRN. In this paper, a simulation method, in which a simplified finite element model of automobile tire with acoustic cavity introducing the rotation of automobile tire is established, is proposed to gain the sound field in the cavity of a rotating automobile tire. And the test of sound pressure in a rotating tire is also performed to validate the proposed simulation method. The comparisons between the simulation and experimental consequences show a satisfying conclusion. Furthermore, the influence factors of the rotating speed, the inflation pressure of the tire and the load on the sound field of automobile tire acoustic cavity are calculated and analyzed.

Mechanical Characterization of Multiwalled Carbon Nanotubes: Numerical Simulation Study

The elastic properties of armchair and zigzag multiwalled carbon nanotubes were investigated under tensile, bending, and torsion loading conditions. A simplified finite element model of the multiwalled carbon nanotubes, without taking into account the van der Waals interactions between layers, was used to assess their tensile, bending, and torsional rigidities and, subsequently, Young’s and shear moduli. Relationships between the tensile rigidity and the squares of the diameters of the outer and inner layers in multiwalled carbon nanotubes, and between the bending and torsional rigidities with the fourth powers of the diameters of the outer and inner layers, were established. These relationships result in two consistent methods, one for assessment to the Young’s modulus of armchair and zigzag multiwalled carbon nanotubes, based on tensile and bending rigidities, and the other to evaluate shear modulus using tensile, bending, and torsional rigidities. This study provides a benchmark regarding the determination of the mechanical properties of nonchiral multiwalled carbon nanotubes by nanoscale continuum modeling approach.

Influence of a Biocompatible Hydrophilic Needle Surface Coating on a Puncture Biopsy Process for Biomedical Applications

A puncture biopsy is a widely used, minimally invasive surgery process. During the needle insertion process, the needle body is always in direct contact with a biological soft tissue. Tissue adhesion and different degrees of tissue damage occur frequently. Optimization of the needle surface, and especially the lubrication of the needle surface, can deal with these problems efficiently. Therefore, in this paper, a biocompatible hydrophilic coating was applied onto the surface of a needle to improve the surface quality of the needle surface. Further, a simplified finite element model of insertion was established, and extracorporeal insertion experiments were used to verify the accuracy of the model. Then, by analyzing a simulation model of a coated needle and a conventional needle, the influence of the application of the coated needle on the insertion process was obtained. It can be seen from the results that the coating application relieved the force on the needle and the soft tissue during the insertion process and could significantly reduce friction during the insertion process. At the same time, the deformation of biological soft tissue was reduced, and the adhesion situation between the needle and tissue improved, which optimized the puncture needle.