The Spot Weldability of Carbon Steel Sheet

The specimens of thickness 0.8 mm carbon steel number 1.8902 in a strip form were welded. The strips of lap joints and curved peeljoints configurations have been welded. The welding parameters such as weld current and weld time have been investigated. The relation between the weld area and the joint strength properties has been presented. The obtained results were showing that the weld joint strength and the molten area (weld nugget volume) highly increase with the increasing of weld current. Therefore, the correlation between the maximum load (joint strength) and area has been given. The reliable weldability under the tensile and shearing loading was considered. Therefore, the new limits of weldability have been presented to consider these two types of loading. Moreover, the experimental results were compared with the empirical relations that consider the sheet thickness only

Analysis of Friction Stir Welds. Part I: Transient Thermal Simulation Using Moving Heat Source

This paper describes the first part of the development of a non-linear finite element simulation of the friction stir welding process; it is concerned with thermal analysis. A transient, three dimensional, non-linear thermal model with moving heat source was developed. Also a steady-state, three dimensional, non-linear fluid-thermal model with stationary heat source was developed. Differences of results for both models were discussed. Results of both models were compared with experimental work. Transient thermal model results appear to be more reliable as compared to the CFD approach

Defects Analysis of Tee-Section Welding Using Friction Stir Welding Process of Aluminum

Friction stir welding (FSW) of Tee-joints is obtained by inserting a specially designed rotating pin into the clamped blanks, through top plate (skin) to bottom plate (stringer), and then moving it along the joint, limiting the contact between the tool shoulder and the skin. The present work aims to investigate the defects occur for Tee-joint of an Aluminum alloy (Al 5456) with dimensions (180mm x 70mm) for the skin plate, (180mm x 30mm) for stringer plate and thickness of (4mm). The effects of welding parameters such as rotational speed, linear speed, plunging depth, tool tilting, and die radii of welding fixture on the welding quality of Aluminum Alloy will be studied. Weld defects had been summarized and studied, and then the best conditions that led to good welds had been estimated.

THE INFLUENCE OF TOOL GEOMETRY OF FRICTION STIR WELDS ON MECHANICAL PROPERTIES AND MICROSTRUCTURE OF 2218-T72 ALUMINUM ALLOY

Friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt. This process uses a nonconsumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force, etc., and tool pin profile play a major role in deciding the weld quality. In this investigation an attempt has been made to understand the effect of tool pin profile and rotation diameter on microstructure and mechanical properties in aluminum alloy (2218-T72). Five different tool pin profiles (straight cylindrical, threaded cylindrical, triangular, square, and threaded cylindrical with flat), with three different rotation diameter (3, 4, 5) mm. have been used to fabricate the joint. Effect of tool pin profile on mechanical properties of welded joints were investigated using different mechanical tests including (tensile, bending and microhardness tests). Microstructure characteristic during (FSW) process was studied and different welding joint were investigated using optical microscope. Based on the stir welding experiments conducted in this study the results show that aluminum alloy (2218-T72) can be welded using (FSW) process with maximum welding efficiency (86.95%) and (83.21%) in terms of ultimate tensile strength and bending force respectively using tool pin profile (threaded cylindrical with flat) with rotation diameter (5) mm, rotation speed (900rpm) and (30mm/min) welding speed

Material Selection for Unmanned Aerial Vehicles (UAVs) Wings Using Ashby Indices Integrated with Grey Relation Analysis Approach Based on Weighted Entropy for Ranking

The designer must find the optimum match between the object's technical and economic needs and the performance and production requirements of the various material options when choosing material for an engineering application. This study proposes an integrated (hybrid) strategy for selecting the optimal material for an engineering design depending on design requirements. The primary objective is to determine the best candidate material for the drone wings based on Ashby's performance indices and then rank the result using a grey relational technique with the entropy weight method. Aluminum alloys, titanium alloys, composites, and wood have been suggested as suitable materials for manufacturing drone wings. The requirements for designing a drone's wings are to make them as light as possible while meeting the stiffness, strength, and fracture toughness criteria. The conclusion indicates that Carbon Fiber-Reinforced Polymer (CFRP) is the best material for producing drone wings. In contrast, wood and aluminum alloys were the cheapest materials when the design had to be inexpensive

EXPERIMENTAL STUDY OF FRICTION STIR SPOT WELDING FOR BRASS ALLOY(426/1CUZN10)

Friction stir spot welding (FSSW) is a promising solid state joining process and is widely being considered for automotive industry. In this work mechanical properties of friction stir spot welded joints were investigated for ISO(426/1CuZn10) copper alloy. The effect of main welding parameters were studied including, welding tool rotational speed, preheat time (15, 30)s , plunging time (10,30)s , dwell time 10 s ,plunging depth (0.7,0.8) mm. Group of matrices of welding parameters were used to study the effect of each parameter on properties of welded joints. Series of (FSSW) experiments were conducted using manual drilling machine. Effect of welding parameters on mechanical properties of welded joints were investigated using tensile shear test. Micro-hardness test used to indicate the changes in hardness across welding region. Based on the welding experiments conducted in this study, the results show that copper alloy (426/1CuZn10) was easy weldable using (FSSW) process with maximum failure load (420 N) at (2000 rpm) rotating speed and ( 70 s) total time for (0.5 mm) sheet thickness

Material Selection Using Hybrid Grey Relation Analysis Approach Based on Weighted Entropy for Ranking: The Case of Helicopter Rotor Blade

Engineering design relies highly on the selection of suitable materials. Because there are many engineering materials, selecting a suitable material for a product requires a systematic selection approach. This paper provides a hybrid strategy for choosing the best material for an engineering design to give the best performance at the lowest cost based on Ashby's performance indices. Then, it ranks the result by the grey relational approach integrated with the Weighted Entropy Method to choose the optimum material for the main rotor blade of a helicopter. Different materials used for manufacturing rotor blades, such as Aluminium alloys, titanium alloys, steel, composites, and wood, have been discussed. The performance indices chosen are stiffness, strength, and fracture toughness. The performance indices proved that the composite material has excellent structural strength, stiffness, and toughness. The result shows that CFRP is the best material for manufacturing helicopter rotors, while wood and steel were the best and cheapest when the design had to be economical

THEORETICAL ANALYSIS OF TEMPERATURE DISTRIBUTION IN FRICTION STIR WELDING

Friction stir welding (FSW) is a relatively new welding process that may have significant advantages compared to the fusion processes as follow: joining of conventionally non-fusion weldable alloys, reduced distortion and improved mechanical properties of weldable alloys joints due to the pure solid-state joining of metals. In this paper, a two-dimensional model based on finite element analysis is used to study the thermal history and thermomechanical process in the butt-welding of aluminum alloys. The model incorporates the mechanical reaction of the tool and thermomechanical process of the welded material. The heat source incorporated in the model involves the friction between the material and the probe and the shoulder. The calculation result also shows that preheat to the workpiece before process is beneficial to FSW. The effects of welding parameters such as preheating (100, 200) °C, rotational speed (960, 1200) rpm and linear speed (110, 155, 195) mm/min on the distribution of temperature of Al Alloy will be studied

A patient safety toolkit for family practices

Objectives: Major gaps remain in our understanding of primary care patient safety. We describe a toolkit for measuring patient safety in family practices. Methods: Six tools were used in 46 practices. These tools were: NHS Education for Scotland Trigger Tool, NHS Education for Scotland Medicines Reconciliation Tool, Primary Care Safequest, Prescribing Safety Indicators, PREOS-PC, and Concise Safe Systems Checklist. Results: PC-Safequest showed that most practices had a well-developed safety climate. However, the Trigger Tool revealed that a quarter of events identified were associated with moderate or substantial harm, with a third originating in primary care and avoidable. Although medicines reconciliation was undertaken within 2 days in >70% of cases, necessary discussions with a patient/carer did not always occur. The prescribing safety indicators identified 1,435 instances of potentially hazardous prescribing or lack of recommended monitoring (from 92,649 patients). The Concise Safe Systems Checklist found that 25% of staff thought their practice provided inadequate follow-up for vulnerable patients discharged from hospital and inadequate monitoring of non-collection of prescriptions. Most patients had a positive perception of the safety of their practice although 45% identified at least one safety problem in the past year. Conclusions: Patient safety is complex and multidimensional. The Patient Safety Toolkit is easy to use and hosted on a single platform with a collection of tools generating practical and actionable information. It enables family practices to identify safety deficits that they can review and change procedures to improve their patient safety across a key sets of patient safety issues

Patients’ evaluations of patient safety in English general practices: a cross-sectional study

Background: The frequency and nature of safety problems and harm in general practices has previously relied on information supplied by health professionals, and scarce attention has been paid to experiences of patients. Aim: To examine patient-reported experiences and outcomes of patient safety in Primary Care in England. Design and Setting: Cross-sectional study in 45 general practices. Method: A postal version of the Patient Reported Experiences and Outcomes of Safety in Primary Care (PREOS-PC) questionnaire was sent to a random sample of 6,736 patients. Main outcome measures included “practice activation” (what does the practice do to create a safe environment); “patient activation” (how pro-active are patients in ensuring safe healthcare delivery); “experiences of safety events” (safety errors); “outcomes of safety” (harm); and “overall perception of safety” (how safe do patients rate their practice). Results: 1,244 patients (18.4%) returned completed questionnaires. Scores were high for “practice activation” (mean (standard error) = 80.4 out of 100 (2.0)) and low for “patient activation” (26.3 out of 100 (2.6)). A substantial proportion of patients (45%) reported having experienced at least one safety problem in the previous 12 months, mostly related to appointments (33%), diagnosis (17%), patient-provider communication (15%), and coordination between providers (14%). 221 patients (23%) reported some degree of harm in the previous 12 months. The overall assessment of the level of safety of their practices was generally high (86.0 out of 100 (16.8)). Conclusion: Priority areas for patient safety improvement in general practices in England include appointments, diagnosis, communication, coordination and patient activation