Underground gas pipelines are one of the vital parts of each country which surface blasts can break down such pipelines, making destructive explosions and threatening the safety of neighborhood structures and people. In this paper, to enhance the safety of these lines, response of a buried 56-inch diameter high pressure natural gas pipeline to a surface blast was numerically investigated. Besides, the effects of: i) explosive mass, ii) pipeline thickness, iii) burial depth and iv) concrete protective layer on pipeline deformation were parametrically studied. To simulate the problem according to actual explosion events, geometries were modeled in real scales, pipeline properties were predicted with Johnson-Cook strength and failure model and soil strength was determined by Drucker-Prager model. Also, explosive charge and natural gas were modeled with JWL (Jones-Wilkins-Lee) and ideal gas equation of states. For validation of the numerical method, three bench mark experiments were reproduced. Comparison of the numerical results and the experimental data confirmed the accuracy of the numerical method. Results of parametric studies indicated that by increasing the burial depth from 1.4 to 2.2 m, deformation of the pipeline was reduced about 71%. By analyzing the deformation plots, it was found that in a constant explosive mass, burial depth has a greater effect than pipeline thickness on pipeline deformation reduction. It was also shown that using a concrete protective layer may act reversely and increase pipeline destruction. In other words, to enhance the safety of pipelines, a certain thickness of concrete must be used.

A review of some recent data from multiaxial fatigue data from different notched materials is carried out in the paper. The approach based on the strain energy density (SED) averaged over a control volume is first used to summarise uniaxial and multiaxial fatigue strength data of welded joints made of structural steel and aluminium alloys. In all welded joints, the weld toe and weld root regions are modelled like sharp, zero radius, V-notches with different opening angles. The control volume radius is 0.28 mm for structural steels, 0.12 mm for aluminium alloys. Afterwards the SED approach is applied to multi-axial fatigue data from plain and V-notched specimens made of AISI 416 stainless steel (hardened and tempered state), subjected to tension, torsion and combined tension and torsion, both in-phase and out-of-phase. Notched specimens are characterised by a very small root radius, ρ=0.1 mm, which results in high nonlinear effects ahead of the notch tips. All results are summarised in terms of Δ W-N (SED range versus cycles to failure) scatterbands. Together with the new results, a number of multi-axial fatigue data recently obtained from sharply notched specimens made of C40 steel (normalised state) and 39NiCrMo3 steel (hardened and tempered state) are represented with the aim to provide a global synthesis in terms of local SED. Finally a synthesis from Ti6Al4V alloy is carried out showing the capability of the SED approach to be applied also to light alloys.

The problem of thermoelastic nanoscale beam based on a modified couple stress theory with diffusion subjected to ramp type heating is investigated. The Laplace transform technique and eigen value approach are applied to solve the equations which are written in the dimensionless form. The expressions for displacement, lateral deflection, temperature change, mass concentration, axial stress and chemical potential are derived in the transformed domain. A general algorithm of the inverse Laplace transform is developed to compute the results numerically. The mathematical model is prepared for Copper material. The resulting quantities are depicted graphically to show the effects of time. Some particular cases of interest are also deduced from the present problem.

The cost of road construction or its repair is among the most concerns for the pavements engineers. Cracking and degradation is common mode of failure in asphalt pavements that occurs due to increasing traffic loads or even environmental conditions. For facing with these damages, some solutions are proposed including correction, quality improvement and increasing the asphalt resistance. In this research, by adding different percent amounts of black nano-carbon and polyester fibers as modifier in the asphalt mixtures and conducting several Marshall tests, it was observed that adding these two additives can improve generally the Marshall results. Polyester fiber causes preventing crack and damages of asphalt because of armed effect specification. According to the results, Marshall stability is increased up to 61%. Furthermore, an economic analysis was performed to investigate the cost of using such modified asphalt mixtures for constructing 1 km of a six line road and suitable percentages of additives were found from mechanical-economic analyses.

Portland cement concrete (PCC) / asphalt concrete (AC) bonded components are seen in both conventional pavement structures as well as overlays. Due to the environmental and traffic loads, cracks occur at the interface of the PCC and AC layers and finally, may propagate through the interface or one of the layers. Therefore, the evaluation of bond strength between these layers is important. This paper investigates bond strength between asphalt concrete and Portland cement concrete using a new sandwich test specimen. The developed specimen, called Bi-material semi-circular bend (BSCB) is made of asphalt concrete and the Portland cement concrete, cracked at the interface of the materials. First, the suggested specimen is introduced and characterized using finite element simulation. Then, the specimen is employed to obtain bond strength between asphalt concrete and Portland cement concrete under mixed mode loading, and at two temperatures: -20C and 20C. The fracture toughness at different mixed mode conditions is obtained, and finally, fracture criterion for the tested bonded joints is presented.

Considering accurate constitutive models is of the utmost importance to capture mechanical response of soft tissue and biomedical materials under physiological loading conditions. This paper investigated the behaviour of porcine myocardium of passive rested hearts. This was investigated by applying biaxial loads on the myocardium. The main objective of this research was to investigate the cardiac mechanics of various regions in the healthy passive of a porcine. The biaxial mechanical properties of myocardial tissue samples were captured using a biaxial testing system. The porcine heart was divided into three regions, namely: left ventricle (LV), septum and right ventricle (RV). In these regions, 18×18 mm2 equal samples were cut from six porcine passive hearts. For the LV sample, biaxial elastic modulus in the fibre direction is 33.3% larger than in the cross fibre direction. For the mid-wall sample, biaxial elastic modulus in the fibre direction is 18.8% larger than in the cross fibre direction. For the RV sample, biaxial elastic modulus in the fibre direction is 33.3% larger than in the cross fibre direction. It was concluded that the cardiac mechanics of LV, Septum and RV exhibit different mechanical behaviour. The mechanical behaviour exhibited by various regions (LV, Septum and RV) in the healthy porcine heart differs considerably. To develop adequate computational models, these data could be utilized to estimate the material parameters of the myocardium.

The linear elastic analysis of homogeneous, isotropic cracked bodies started in the 1900s. The existence of three dimensional corner point effects in the vicinity of a corner point where a crack front intersects a free surface was investigated in the late 1970s. An approximate solution by Bažant and Estenssoro explained some features of corner point effects but there were various paradoxes and inconsistencies. Results derived from finite element models showed that the analysis is incomplete. The stress field in the vicinity of a corner point appears to be the sum of two different singularities (i.e. stress intensity factors and corner point singularities). In this paper some recent results for the corner point singularities under in and out of plane loadings is reviewed and discussed.

This article discusses possibilities of application of widely applied and promoted abroad methods of active dampening of vibration and pressure oscillations (antinoise technology) in order to reduce vibration transfer via vibro-insulating couplings (compensators) of fluid pipelines. This is required in solution of issues of vibration insulation of equipment with regard to foundation and environment along pipelines with working mediums, for instance, in transporting of oil and gas, in energy and transport engineering. Reasonability of operation of active system in combination with means of passive dampening of these impacts is demonstrated. In terms of efficiency and minimum energy consumptions by active system it is reasonable to apply active dampening of vibration and oscillations downstream of the vibro-insulator (compensator) where their level is significantly lower than in the source. In the case of pipeline this implies dampening of vibration and oscillation downstream of compensator and damper, however, such works are nearly unavailable. This is attributed to significant coupling between vibration and pressure oscillation in compensator and pipeline itself, complicating solution of the problem. It is concluded that for efficient application of active dampening in pipeline compensators it is required to develop compensators with minimum coupling between vibration and oscillations.

An approximated crack growth direction and coalescence of the multiple cracks were obtained for an aluminum alloy plate by the finite element approach (FEA). Self-similar as well as non-self-similar crack growths were observed based on relative position of multiple cracks. The FE predictions of crack growth direction are validated with an experimental results and good agreement is established. Typical numerical results are presented to examine the effect of changing the crack tip distance (S), crack offset distance (H) on crack growth direction and coalescence of a finite aluminum alloy aluminum plate. Based on the analysis and experimental results, a new mathematical models for self-similar and non-self similar crack growth are introduc

Quality of blast preparation for rock beneficiation influences both on integrity of mineral stock in particular and in economical performances of enterprise operations in general. While rock processing for obtaining of crushed stone the yield of screenings is high, its amounts depend on rock strength properties. Investigation into the influence of drilling and blasting parameters on strength properties of blasted rocks is an urgent research and practical task for mining companies producing building stones. This article discusses results of full-scale experiment aimed at determination of strength of blasted rocks in shotpile with accounting for fracture zones as a function of rock massif saturation with energy of explosive substance.