DEVELOPMENT OF A MEASUREMENT SYSTEM FOR THE EVALUATION OF KINEMATICS AND IMPACT FORCES IN HISTORICAL FENCING COMBAT

This study aims at evaluating the impact forces acting on the blades of swords during a combat. Such forces will be used as input for numerical simulations to estimate the sword durability. Some replicas of the 17th century swords were instrumented with strain gauges and inertial sensors were placed on athletes’ joints to reconstruct arm kinematic. The forces along the two relevant axes are calculated by linear regression of two Wheatstone bridges and results were consistent with previsions. The calibration showed small uncertainty (max 11 N) with the transverse sensitivity being directly included in calibration parameters. In addition, the system was fully synchronized between all its parts and the bandwidth seems sufficient to calculate the impacts

Numerical, Mechanical, and Metallurgical Investigation of an Innovative Near Net Shape Titanium Selective Laser Melting Engine Component and Comparison with the Conventional Forged One

Selective laser melting (SLM) can be used to manufacture near net shape (NNS);the main benefits are a remarkable weight reduction, a lower environmentalimpact, the opportunity to integrate some functions, and an improvement of theperformances. The current article covers the development of a Ti6Al4V NNS enginecomponent produced by SLM. Finite element analyses of the main relevantoperating conditions are performed to reach a topological optimization of the part.The main target is weight reduction keeping the same safety performances. Theweight reduction achieved is 45% and 15% with respect to steel and titaniumforging by replacing the original“H”section with an SLM multibranch structure.Other benefits are the manufacturing of the connecting rod (conrod) into twoseparate parts, avoiding the difficult machining to separate the cap from the mainbody and the integration of conformed cooling channels into the conrod. Then, theSLM components are produced and mechanical and metallurgical properties areinvestigated and compared with the titanium hot forging ones. Both the macro-structures present equiassic and isotropic behavior due to the heat treatmenttransformation. No defects are observed for both the technologies. The mechanicalproperties are verified to be aligned with the design targets

Study and Characterization of EN AW 6181/6082-T6 and EN AC 42100-T6 Aluminum AlloyWelding of Structural Applications: Metal Inert Gas (MIG), Cold Metal Transfer (CMT), and Fiber Laser-MIG Hybrid Comparison

The present research investigates the eects of dierent welding techniques, namely traditional metal inert gas (MIG), cold metal transfer (CMT), and fiber laser-MIG hybrid, on the microstructural and mechanical properties of joints between extruded EN AW 6181/6082-T6 and cast EN AC 42100-T6 aluminum alloys. These types of weld are very interesting for junctions of Al-alloys parts in the transportation field to promote the lightweight of a large scale chassis. The weld joints were characterized through various metallurgical methods including optical microscopy and hardness measurements to assess their microstructure and to individuate the nature of the intermetallics, their morphology, and distribution. The results allowed for the evaluation of the discrepancies between the welding technologies (MIG, CMT, fiber laser) on dierent aluminum alloys that represent an exhaustive range of possible joints of a frame. For this reason, both simple bar samples and real junctions of a prototype frame of a sports car were studied and, compared where possible. The study demonstrated the higher quality of innovative CMT and fiber laser-MIG hybrid welding than traditional MIG and the comparison between casting and extrusion techniques provide some inputs for future developments in the automotive field

Microstructural, Mechanical, and Tribological Evolution under Different Heat Treatment Conditions of Inconel 625 Alloy Fabricated by Selective Laser Melting.

dditive manufacturing (AM) can be particularly advantageous to manufacture components designed to meet challenging structural requirements. Selective laser melting (SLM) microstructure is different than that obtained by traditional manufacturing process; in particular, mechanical and microstructural features achieved herein are influenced by the entire thermal history, including the manufacturing process and the heat treatment (HT) with relevant role of the slow cooling rate adopted. In fact, both the process and the HTs can significantly modify the microstructure and related mechanical and tribological properties. To better understand how mechanical response can be tuned to meet different requirements, in this article the effects of four different vacuum HTs on microstructures, mechanical properties, and wear behavior of Inconel 625 produced with SLM are deeply investigated. In general, the results confirm that HT can significantly change the microstructure and mechanical or tribological properties of Inconel 625. Among the examined HT, solution + aging and direct aging improve the strength of the alloy, whereas annealing leads to recrystallization, reducing strength in favor of ductility. Stress relieving does not significantly change the microstructure and mechanical properties. Considering tribological behavior, only direct aging HT leads to a remarkable improvement, with a reduction in friction coefficient and wear rate

Microstructural, Mechanical, and Tribological Characterization of Selective Laser Melted CoCrMo Alloy under Different Heat Treatment Conditions and Hot Isostatic Pressing.

A deep knowledge of material properties is fundamental to obtain high-performance medical implants realized with CoCrMo alloy manufactured by selective laser melting (SLM), even more so when considering that heat treatments (HTs) are often necessary to refine the microstructure, eliminate residual stress, and improve mechanical properties. To this aim, herein, SLM CoCrMo alloy samples are produced in six different treatment conditions: as built (AB), four different vacuum HTs, and hot isostatic pressing (HIP). Modifications to microstructure, hardness, tensile behavior, and wear resistance are then investigated. Results reveal that vacuum HTs and HIP have different effects on microstructure and types of defects with respect to the AB condition. Thus, proper selection of the treatment is mandatory to improve specific mechanical properties, such as strength, ductility, hardness, or tribological response. In this context, it is confirmed that the choice of an appropriate HT allows SLM CoCrMo to reach the target mechanical properties set by international standards for applications in the medical field, such as dentistry or orthopedics

A study of a non-conventional evaluation of results from salt spray test of aluminum High Pressure Die Casting alloys for automotive components

Aim of the present work was to investigate in a non-conventional way the results of aluminum castings salt spray tests. These experiments were engineered in order to obtain a quantitative measurement of the corrosion rate, instead of the qualitative visual analysis usually employed in the traditional salt spray test. These tests were performed on aluminum EN AC-46000, EN AC-44400, and EN AC-43500 samples. A comparison was made with electrochemical tests on specimens and the traditional salt spray testing on a real dimension component. The results showed a good reliability of the new method that gave outputs in agreement with the electrochemical technique. The new concept of salt spray test data processing was able to detect very small differences in corrosion behavior of tested alloys, demonstrating higher precision and reliability in respect to the polarization technique. Such result was explained considering the adoption of specimen with larger area and longer time of exposure to the selected corrosive environment that reduce respectively the effect of uneven distribution of porosity and intermetallics in the samples, typical of aluminum castings, and the potential local and transient events related to these defects

Characterization and Technological Origin Identification of Ancient Iron Nails

Metallurgical analyses and mechanical tests were performed on two ancient iron nails (dated to the seventeenth and eighteenth centuries) found at a private estate in the village of Limone sul Garda, which is located on Lake Garda in the northern Italian region of Lombardy. The nails were characterized via various metallurgical methods to assess their matrix composition, microstructure, and nonmetallic inclusion type, morphology, and distribution. These investigations elucidated the manufacturing process of the nails. The results indicated that the nails were produced by different forging techniques, and it was hypothesized that the steel utilized was obtained via two different methods (direct and indirect ore reduction), which were still in use at that time

A comparative study of mechanical properties of metal inert gas (MIG)-cold metal transfer (CMT) and fiber laser-MIG hybrid welds for 6005A T6 extruded sheet,

Among the several welding technologies available today, traditional metal inert gas (MIG) one is widely used for junction of Al-alloys parts in transportation field, while cold metal transfer (CMT) and laser techniques are recent alternatives potentially providing advantages over the former one, such as reduction of deformations and reduced alteration of base material. The present research aims to investigate the effects of these different techniques on the microstructural and mechanical (hardness, tensile strength, yield stresses, and elongation) properties of welded joints of 6005A-T6. Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDS) was used for fractographic observations and to analyze microstructural changes after welding. From this examination, it is found that CMT and fiber laserMIG hybrid joints of AA6005 aluminum alloy showed superior mechanical properties compared with MIG weld

Cradle-to-Gate Impact Assessment of a High-Pressure Die-Casting Safety-Relevant Automotive Component

The mass of automotive components has a direct influence on several aspects of vehicle performance, including both fuel consumption and tailpipe emissions, but the real environmental benefit has to be evaluated considering the entire life of the products with a proper Life Cycle Assessment (LCA). In this context, the present paper analyzes the environmental burden connected to the production of a safety relevant aluminum high pressure die casting component for commercial vehicles (a suspension cross beam) considering all the phases connected to its manufacture. The focus on aluminum high-pressure die casting reflects the current trend of the industry and its high energy consumption. This work shows a new method that deeply analyzes every single step of the component's production through the implementation of a wide database of primary data collected thanks to collaborations of some automotive supplier companies. This energy analysis shows significant environmental benefits of the aluminum recycling

Analysis of ancient slag inclusion-metal systems as a method to disclose processing thermo-chemical parameters: the case study of a Medieval Lombard steel bar from northern Italy

An archaeometallurgical characterization of a VI-VII century Lombard steel bar from Ponte di Val Gabbia I site (northern Italy) was performed to reconstruct its manufacturing process and extract processing thermochemical parameters (i.e., temperature and oxygen chemical potential) from the slag inclusion-metal systems. Metallographic observations by optical microscopy and Vickers microhardness measurements indicated that the steel bar was forged from a heterogenous steel lump, most probably an iron bloom, which was cooled in the air after the forging process. The chemical composition of non-metallic inclusions was determined by scanning electron microscopy coupled with X-ray dispersive spectroscopy. A multivariate statistical analysis of the smelting-derived non-metallic inclusions chemistry allowed to conclude that the steel bar was obtained by the direct or bloomery method. Under the hypothesis of local near-equilibrium conditions for the slag inclusion-metal systems, a thermodynamic-based strategy was adopted to estimate the firing conditions in the bloomery furnace in terms of both temperature and oxygen chemical potential of the reducing gas atmosphere. In particular, the computed temperatures are in the range of 1003-1171 °C, whereas the values of oxygen chemical potential vary between -447.47 kJ/mol and -385.79 kJ/mol