Experimental work for mechanical properties of brick and masonry panel

The use of Masonry panels in building construction has been popular in most of the parts of the world. However, the use of bricks and brick masonry in different parts of the world being of different nature in terms of quality, size, workmanship of construction, etc. It is yet a topic of interest to researchers to identify the mechanical properties, like Young’s modulus of elasticity and shear modulus of brick masonry panels. It is essential to know the characteristic of brick masonry panels in order to evaluate the responses of masonry walls for any kind of loading. Individual bricks do possess better compressive capacity as compared to masonry walls. Masonry walls are bound together with either mud mortar or by cement sand mortars of various mixes as per the strength requirements. The essential strength properties in engineering are basically the compressive strength and the modulus of elasticity. The American Society for Testing and Materials (ASTM) standard is the most popular for testing bricks and brick masonry for these properties so far. Here, the study has been concentrated in finding the compressive strength of brick, mortar and brick masonry. The study is also done for Young’s modulus of elasticity of brick as well as that of masonry wall. Similarly, the study is extended to find the modulus of rigidity of brick masonry panel. The study is done experimentally for the samples that are generally used in Kathmandu, Nepal. The samples include bricks, cement and sand particularly available in Kathmandu region.

Dependence of ultrasonic contact impedance hardness on Young’s modulus of elasticity of creep-resistant steels

<p class="Abstract"><span lang="EN-US">The paper deals with the hardness measurements by mobile UCI hardness testers as a means of determining the residual operation life of power unit components. It aims to answer questions regarding the level of dependence of UCI hardness on Young's modulus of creep-resistant steels and determining the conditions of a UCI hardness tester calibration. The experimental part describes comparative measurements of hardness values obtained using stationary hardness testers and UCI hardness testers.</span></p>

Ultrasound elastography as a method of emergency diagnosis of the first signs of transient ischemia of the lower limbs in diabetic foot syndrome

Aim. Evaluate the data of elastography characteristic for the first signs of transient ischemia of lower limbs in diabetes foot syndrome.Methods. In Kazan city clinical hospital №7 measurement of Young’s modulus of elasticity was performed in 12 patients with transient ischemia in diabetic foot syndrome. The methods and assessment of parameters typical for soft tissues of lower limbs we have developed earlier (patent «Method of elastography diagnosis of tissue changes in diabetic foot syndrome»). Color duplex scan of the arteries was performed according to standard method with the use of 5 to 10 MHz linear array probe starting from distal parts of limbs. Measurement of ultrasound density was performed with the use of shear wave elastography with 4 to 15 MHz wide-band linear probe. All parameters were measured in real time mode.Results. Increase of elastomeric index (Young’s modulus of elasticity) to 23.74±2.34 kPa (93,49±1,26%) in the distal segment of the lower extremity (on the foot) is associated with development of transient disorders in the lower limbs in diabetic foot syndrome, which is not always detected with invasive methods of diagnosis.Conclusion. Shear wave elastography is recommended for emergency medical care in diabetic foot syndrome; patients after being diagnosed with type 2 diabetes should dynamically monitor microcirculation of lower limbs that will decrease the risk of need of surgical treatment.

Target Shape Optimization of Functionally Graded Shape Memory Alloy Compliant Mechanism

Nickel Titanium (NiTi) shape memory alloys (SMAs) exhibit shape memory and/or superelastic properties, enabling them to demonstrate multifunctionality by engineering microstructural and compositional gradients at selected locations. This paper focuses on the design optimization of NiTi compliant mechanisms resulting in single-piece structures with functionally graded properties, based on user-defined target shape matching approach. The compositionally graded zones within the structures will exhibit an on demand superelastic effect (SE) response, exploiting the tailored mechanical behavior of the structure. The functional grading has been approximated by allowing the geometry and the superelastic properties of each zone to vary. The superelastic phenomenon has been taken into consideration using a standard nonlinear SMA material model, focusing only on 2 regions of interest: the linear region of higher Young’s modulus of elasticity and the superelastic region with significantly lower Young’s modulus of elasticity. Due to an outside load, the graded zones reach the critical stress at different stages based on their composition, position and geometry, allowing the structure morphing. This concept has been used to optimize the structures’ geometry and mechanical properties to match a user-defined target shape structure. A multi-objective evolutionary algorithm (NSGA II - Non-dominated Sorting Genetic Algorithm) for constrained optimization of the structure’s mechanical properties and geometry has been developed and implemented.

Comparison of Dynamic Young's Modulus of Elasticity Values Measured by Ultrasonic Pulse and Resonance Methods

Dynamic Young ́s modulus of elasticity can be determined by ultrasonic pulse method and resonance method. Because of the difference in the way of introducing tension into a test specimen, the values of modulus of elasticity differ. Dynamic Young ́s modulus of elasticity measured by ultrasonic pulse method is higher; the difference stated for concrete is 5 to 20%. It was found that the dynamic Young's modulus of elasticity of calcium silicate bricks and prisms measured by ultrasonic pulse method is on average higher by 9.5% than dynamic Young's modulus of elasticity measured by resonance method. If dynamic Young's modulus of elasticity is converted to static modulus of elasticity, this difference has to be taken into account by means of appropriate coefficient.

Estimation of an Effective Young’s Modulus of Elasticity in the Locality of the Gabčíkovo Hydrology Power Plant by Geometric Leveling

The Gabčíkovo hydroelectric power plant is located in a complicated geological environment (gravel sub-soil and a high groundwater level). Excavation work started after the withdrawal of water in the autumn of 1984 and lasted until the autumn of 1986. A basic geodetic control network with a special monument was founded before the excavation work began. This network served for the setting-out of the hydroelectric power plant as well as for the control of the excavation work. The repeated geodetic control measurements have been evaluated and presented at many seminars and conferences. Monitoring the horizontal and vertical stability of the geodetic control network during the general site excavation showed significant horizontal and vertical deformations. The paper is focused on an estimation of an effective Young's modulus of elasticity in the area studied.