Study on Size-Related Product Quality of Multiscale Central-Punched Cups Fabricated by Compound Forming Directly Using Brass Sheet

Meso/microforming has gained much more attention in the last decades and is widely used as a reliable method to fabricate meso/micro-scaled metallic components. In this research, a compound meso/microforming system which combines deep drawing, punching and blanking operations was developed to fabricate multiscale central-punched cups by using brass sheets. The parts with three scales were produced by using the brass sheets with various thicknesses and grain sizes to investigate geometrical and grain size effects on the deformation behaviors, dimensional accuracy, and material flow behaviors in the forming process. Through physical experiments and finite element simulations, it is revealed that the ultimate deformation load in the drawing-punching stage is smaller than that in the single deep drawing stage under microscale, but the results in the meso-scaled scenarios are opposite. In addition, the thickness variation is increased with grain size, but the variation of the normalized thickness variation does not show an obvious tendency with different size scales. In the bending area, the material flow is tangential to the thickness direction, leading to the formation of thinning area. In addition, the material flow is almost opposite to the punching direction in the punching area, avoiding the expanding deformation of the hole. Thus, the punching operation barely affects the dimensional accuracy including the thickness and hole diameter of the formed parts. Furthermore, the micro-scaled cups with finer grains have a better surface quality. These findings enhance the understanding of size effect in compound meso/microforming with the combined deep drawing and punching operations.

Experimental Investigation and Optimization of Material Properties of Brass at Different Temperature Conditions Using Taguchi Technique

The present investigation deals with the optimization of the parameters for better formability behaviour of brass sheet metal under uniaxial isothermal Tensile Test by using Taguchi Design of Experiments (DoE). The standard L9 (33) Orthogonal Array was formulated to run the experiments based on Taguchi robust design and accordingly uniaxial isothermal Tensile Test conducted at orientation (00, 450 and 900), temperature (300°C, 400°C, and 500 °C), and strain rate (0.001, 0.01 and 0.1 s−1). Analysis of S/N ratios for Ultimate tensile strength and % elongation reported the optimum condition as orientation at level 1 (in degrees), temperature at level 1(in degree Celsius), and strain rate at level 3 (s-1) and orientation at level 1 (in degrees), temperature at level 3 (in degree Celsius), and strain rate at level 1 (s-1) respectively. ANOVA analysis reported the Temperature as the most significant parameter and its contribution are about 62.109% and 71.924% for ultimate tensile strength and % elongation respectively.

Constitutive Model of Thin Metal Sheet in Bulging Test Considering Strain Gradient Hardening

The study of the size effect was one of the most important subjects in the field of micro-forming. To investigate the stress of the thin sheet in the bulging test with the second order size effect, a constitutive equation considering the strain gradient hardening was proposed. Based on the equation, the stress of the thin sheet during the bulging test was calculated by the finite element method. The bulging tests with various thicknesses of brass sheets and radiuses of punching balls were performed to verify the proposed equation. The results showed that the constitutive equation could capture the stress variations, while the simulation using the constitutive equation from the conventional theory of plasticity showed the results with large deviation from those of the experiment. It was found that the stress was sensitive to the thickness of the sheet and the radius of the punching ball in bulging test of thin brass sheet. The bulging of the thin brass sheet with a thickness below ten times of its material intrinsic length would cause the generation of the geometrically necessary dislocations, which induced the strain gradient hardening. Besides that, the decrement of the punching ball radius would also increase the inhomogeneous deformation and enhance the strain gradient hardening during the thin sheet bulging process. The strain gradient hardening during the thin sheet bulging test was related to the strain of the sheet. The hardening effect of the strain gradient was obvious when the strain was small. The strain gradient hardening should be considered in the thin sheet bulging test with the second order size effect.

ARTISTIC BEAUTY OF THE DIVINE IDOLS OF VIRUPAKSHA MAHADEV TEMPLE BILPANK

This temple is the largest in the West-Malwa region and is an unequaled example of Gurjar Chalukya Shaili (contemporary of Paramara art). This temple is of Panchayat Shaili, this temple has a square sanctum sanctorum, interiors hall and half pavilion in the geo-configuration, the sanctum sanctorum of this temple is 5.20 meters square. At this time, a shivalinga on the vaginapatta covered with brass sheet is revered in the garbhagriha. यह मन्दिर पष्चिमी-मालवा क्षेत्र का सबसे बड़ा व गुर्जर चालुक्य षैली (परमार कला के समकालीन) का अप्रतिय उदाहरण है। यह मन्दिर पंचायतन षैली का है, भू-विन्यास में इस मन्दिर में एक वर्गाकार गर्भगृह, अन्तराल सभामण्डप तथा अर्ध मण्डप है, इस मन्दिर का गर्भगृह 5.20 मीटर वर्गाकार है। इस समय गर्भ गृह में पीतल की चादर से उपाच्छादित योनिपट्ट पर एक षिवलिंग प्रतिष्ठित है।

Analysis of naturally etched surface of brass sheathing from a nineteenth-century shipwreck

The Akko Tower Wreck is ently the remains of a 25-m-long merchant brig, dated to the first half of the nineteenth century. During the 2015 underwater excavation, a piece of brass sheet was retrieved from the shipwreck and its surface and bulk were examined by metallurgical analyses. The examinations revealed a unique example of almost two hundred years? natural etching, which took place in the sea underwater environment. The surface of the sheet was covered with different copper and zinc oxides, which were identified by XRD analysis. Observation of the naturally etched surface with multi-focal light microscopy and SEM-EDS analysis indicated a microstructure of annealed ?-brass, similar to that of its bulk. S-OES chemical analysis of the bulk revealed a composition of 65.0 wt% Cu, 34.4 wt% Zn and 0.6 wt% Pb. Based on the thickness of the sheet and its good state of preservation, it is suggested that it was used as sheathing to protect the hull against marine organisms, and to improve the sailing qualities of the ship. The results provide further information about the Akko Tower shipwreck; and expand our knowledge regarding the corrosion processes and preservation of brass during a long burial period in marine environments.