Foam made panels as efficient building elements are becoming a major role player in modular construction with a variety of applications worldwide. However, construction accuracy, technology, and method can have serious effects on the panels’ behavior. In this study, using a unique pneumatic pressure testing rig, bending tests are conducted on the two types of rigid polyurethane panels. The panels are categorized based on the existence of construction cold joints (seams) as S (Seamless) type and TS (Transverse Seams) type. The S type panels are tested under monotonic uniform loading with a maximum nominal pressure of about 1 atm as the witness specimens. The TS panels are tested under both monotonic and cyclic uniform loading, and the deflections-pressure behavior obtained. The results show that S panels could resist up to 0.77 atm under monotonic uniform loading, while the minimum tensile strength of the foam is 13 MPa. In addition, panels with transverse seams collapsed under monotonic and cyclic loads at an average of 0.46 atm and 0.33 atm respectively but at the same position, located on the seamed section, which represent the same failure mode. Based on the results, the seamed section exhibited a maximum tensile strength of about 33.1% of an intact section under monotonic loading; and 27.9% lower results under cyclic loading.

Structural irregularity is a crucial issue in assessing seismic vulnerability of both new and existing buildings. European technical codes provide simple criteria to define irregularities in plan and in elevation, amplifying the seismic actions and/or introducing torsional effects. Nevertheless, this approach only considers geometrical irregularity. For existing buildings, another source of irregularity comes from the non-uniform distribution of the material strength. In particular, for existing reinforced concrete (r.c.) structures, it is possible to detect significant spread of the concrete compressive strength not only from different structural elements but also from different parts of the same member. In this work, non-linear static analysis is performed on two case-studies of r.c. buildings characterized by geometrical and mechanical irregularity. The resistance of each column is determined with an extensive experimental campaign with in situ and laboratory test (about 600 in situ tests). The results are analyzed considering both local and global effects in terms of resistance of the single elements and of the entire buildings. In this sense, shear and bending failure mechanism are taken into account. The effect of story flexibility is also considered in the models. Fragility curves are calculated for the buildings with random distribution of the compressive strength of the columns. The results are then compared with the approaches proposed by the Eurocodes evaluating in the standard approach proposed by technical codes is conservative or not.

Detecting how a cutout affects the critical buckling load in circular cylindrical shell is a serious issue for the design of the shells used in marine structures, aerospace and automobile applications. In this paper, buckling behavior of aluminum cylindrical shell with rectangular cutout, subjected to axial pressure was studied by means of finite element simulations. The effects of geometric parameters (R, t, a, b and L) on the first buckling mode capacity of the shell were studied. The effects of these factors and their interaction effects were investigated by combined numerical and statistical analysis. The results show that R/b, t and Rt/b were the main effective factors of critical buckling load. Based on the statistical analysis, a model for prediction of the critical buckling load was obtained with an accuracy equal to 95% (R2, R2 (pred) and R2 (adj)). This equation could be used to predict the critical buckling load of an isotropic circular shell with a rectangular cutout.

The aim of this paper is to provide a theoretical analysis on the mechanical power of the mass spring’s system. Some tests are conducted to experimentally evaluate the theoretical analysis and to investigate the mechanical energy ability of this concept. The authors suggest a system used for applications of energy harvesting from roads. The system is able to transform the kinetic energy produced by the passage of vehicles on the road for electrical energy based on the mass-spring using two technologies. The hybrid system has two goals. First, supply the entourage by a mechanism to produce significant electrical power used mainly for public lighting. A device is also provided for storing electrical energy for later use, for home lighting at night or in the case of bad weather. Second, the piezoelectric subsystem controls the spring’s health through analyzing the amplitude and shape of the voltage generated by a piezoelectric material. Finally, an experimental validation of the designed smart speed bump is presented.

This paper presents a study on the structural performance of a modified shear-head assembly for edge steel column embedded in reinforced concrete slab. The structural performance was investigated in terms of punching shear capacity of the reinforced concrete flat slab. The study consisted of a laboratory punching shear test on the contra-flexure bound slab of dimension 1060mm × 1250mm by 130mm thick in a reactant test frame using a 500kN load cell. Results of the experimental study was validated using finite element based numerical method. Both experimental and numerical results show that increase in tensile strength of concrete, increases punching shear capacity of the connection. It was also observed that punching shear failure of the connection depended largely on concrete shear strength. This study has also revealed that punching shear occurs when concrete shear strength is reached, irrespective of the robustness of the shear-head connection.

In this paper, a method for determining the limit load surface of fiber-reinforced nonlinear composites such as elasto-plastic composite is proposed. Using the stress approach of the homogeneous theory and the linear matching method (LMM), the limit load surface of the fiber-reinforced composite is numerically evaluated in the π-plane, and at the same time, two limit analyses determine the approximate Hill's anisotropic yield criterion for the limit load surface of the fiber-reinforced composite. The Hill's yield criterion determined by 2 limit analyses becomes the inscribed ellipse of the limit load surface evaluated numerically in the π- plane, and the limit load surface can be evaluated more accurately by the two tangent lines perpendicular to the minor axis of the inscribed ellipse and the circumscribed circle of the inscribed ellipse. This means that the limit load surface of fiber-reinforced nonlinear composite can be completely determined by only 2 limit analyses. In addition, it is found that the limit load surface is related to the equivalent strength surface of composite, and that it satisfies the Reuss and Voigt bounds.

In this study, a 3D finite element model of an intact mandible was used for the simulation of the movement of the lower jaw and analysis of the effects of TemporoMandibular Joint (TMJ) prosthesis replacement on the jaw movement. Seven bundles of muscle fibers were inserted in their appropriate positions following anatomical data. Digastric, geniohyoid and lateral pterygoid muscles were considered for opening the mouth while medial pterygoid, superficial masseter, deep masseter and temporalis muscles were used for closing the mouth. Then, the TMJ was replaced by two different types of TMJ prostheses in the same way as in a surgery operation. One of the prostheses was designed based on anatomical shape of the ramus and condyle of the mandible while the other one was taken similar to the commercial TMJ prostheses. Eventually, all three models underwent an opening jaw simulation and produced an identical range of motion while were mismatched in other parameters. The results show that since the anatomical TMJ prosthesis resembles the shape and structure of an intact mandible; therefore, it is more capable of simulating the motion of mandible compared to the commercial TMJ prosthesis. Furthermore, better contact between the anatomical TMJ prosthesis and the mandible leads to lower stress distribution in comparison with the commercial TMJ implant. Finally, as the amount of muscle forces and strain in anatomical TMJ prosthesis replacement are less than the commercial one, the patient needs to make less effort to move the mandible and open the mouth.

Proper functioning of electrical connectors used in high oscillation is of great importance. Vibrations in connector pins cause stress and electrical resistance variations in the contact surface. In the present paper, the impacts of vibrational loads on electrical connectors is being modeled using the finite element method, and the electrical resistance oscillations of the connectors will be examined. Ultimately, the parameters affecting the electrical resistance oscillations of contacts will be determined and their relations with oscillations in electrical resistance are specified as well.

In the present work, an elasto-plastic model is proposed for the numerical analysis of dynamic nonlinear behavior of composite thick shells with reinforcements in spirals subjected to impulsive loading. Wilkins algorithm was taken to analysis physical and geometrical non-linearity of stress-strain state of elasto-plastic thick composite shells. This study is carried out on two types of cylindrical composite shells in different reinforcement winding angles and different magnitudes of impulse loads. By a calculation code in finite difference, first the influence of physical non linearity on the stress-strain state of cylindrical monolayer shell was established and then the relationship between residual strains and the winding angle of the symmetric reinforcements was investigated. Finally, the influence of the winding angle of the orthogonal reinforcements on the residual strains of a bilayer composite shell was analyzed numerically.

Heterogeneity is an important factor controlling fracture initiation, accumulation, and propagation within rock destruction. Traditionally, rock reaction instability within rock destruction is associated with rock non-homogeneity or considered self-excited, but no clear relations between rock structure options and reaction force oscillation were proposes. This work hypothesizes the idea rock structure options are one of the factors of drill bit whirling. The authors innovated the Wojtanowicz and Kuru’s force static balance model to numerically simulate 3-cutter movement in a rock space, assuming a crack propagates by rock grains getting around. Instability of deviation between directions of cutting force and crack propagation causes rock reaction instability. Novelty of this work is to consider the mutual influence of rock granulomentric composition options (sizes, shape and distribution of grains) and drill bit design options (cutter diameter, distance between adjacent cutters, etc.) on rock reaction force oscillation. The follow tendencies were observed: rock grain dimension increasing and grain concentration increasing were accompanied with rock reaction force magnitude decreasing; random grain placing and/or grain random dimensions caused increasing of rock reaction force scattering; random grain sizes are more essential for rock reaction forces (and their projections) scattering than random grain distribution.