21 research outputs found
Modularity as a design strategy for complex products: Case study electro-solar vessel
No full textThis paper presents a modularity analysis for the design of complex products, based on domain theory, applied to the case study of the design of an electro-solar vessel to be implemented in South American rivers. The proposed approach allows obtaining graphical information from the functional analysis tools, about the interaction between functional modules or organs of the system in terms of material, energy, or information flows; useful to analyze the functional architecture, the types of modularity and the interactions in the system. This information is complemented with the approach to the physical architecture of the system identifying interferences and restrictions. This information is intended to be useful in the development of methods or methodologies for the definition of the assembly sequenc
Determination of stress shielding due to magnesium internal bone fixation
No full textBone is a part of the body that functions as a body frame that provides attachment to muscles and organs in a person’s body. There are to methods for restoring broken bones, external bone fixation and internal bone fixation. External bone fixation is a method with a device placed outside the skin to stabilize bone fragments using pins that are connected to one another with an outer frame or rigid bars. Internal bone fixation is a method that aims to improve stability and encourage bone healing in a functional position. In the process of connecting the bones, there is stress shielding which causes pain to the patient. Stress shielding analysis carried out in the process of connecting bones using stainless steel and titanium as a comparison material of the use of magnesium for screws and plates in the process of bone fixation. Magnesium is also known as a biodegradable material. The analysis of static loading shows that bones with stainless steel plate and screws have a greater maximum von mises stress value than bone with titanium plate and screws, whereas bones with titanium plate and screws have a greater maximum von mises stress value than bone with magnesium plate and screws. The stress shielding calculation results show that the bone with titanium plate and screws have a value of 1.98, the bone with stainless steel plate and screws have a value of 3.82, the bone with Magnesium plate and screws have a value of 1.52. The Magnesium is a potential material for replacing Titanium and Stainless Steel as raw material of plate and screw in a internal bone fixation due to the low stress shielding.</p
Design and Development an Ergonomic Transfer Lifter Assistor From Wheelchair To Bed Transfer For Patients Under 50kg
No full textMoving a patient from their bed to some other places for daily routine is such hard work. Caregiver usually using a wheelchair to move a patient from place to place. Nevertheless, they are facing a problem in lifting the patient from bed to wheelchair. The caregiver needs to use lots of energy to lift the patient into a wheelchair, and it may take a long time. This study focuses on design and develop a transfer lifter assistor to assist the caregiver move the patient from bed to another place. It was flexible and easy to conduct. This innovation's advantages are that the height could be adjusted, making the patient more comfortable to sit on from a bed. The size could be adjusted up to 3 and a half feet. The structure mostly from steel and can be disassembled for storage purposes. The result shows that Transfer Lifter Assistor can perform effectively to lift patients with a maximum weight of 50 kilograms. It can support one patient at a time. This innovation has been successfully produced with cost-effective and can be owned by everyone
Finite element analysis of repetitive corrugation and straightening die designs for severe plastic deformation of magnesium alloy
No full textSynthesis of hydroxyapatite from seashells via calcination at various temperature using microwave and furnace
No full textHybrid Experimental-Computational Approach for Solder/IMC Interface Shear Strength Determination in Solder Joints
No full textHybrid experimental-computational approach for solder/IMC interface shear strength determination in tin-lead solder joints
No full textDamage-based models for solder/intermetallics (IMC) interface often require the interface properties such as tensile and shear strengths. The minute size of the solder joint renders direct experimental determination of these properties impractical. This paper presents a hybrid experimental-computational approach to determine the shear strength of solder/IMC interface. Displacement-controlled ball shear tests are performed on as-reflowed and thermally-aged solder specimens. The observed sudden load drop in the load-displacement curve corresponds to the crack initiation event and the load is indicative of the shear strength of the solder/IMC interface. Finite element simulation of the ball shear test is then employed to establish the complex stress states at the interface corresponding to the onset of fracture. The finite element model consists of Sn40Pb solder, Ni3Sn4 intermetallic and Ni layers, copper pad and a rigid shear tool. Unified inelastic strain theory describes the strain rate-dependent response of the solder while other materials are assumed to behave elastically. Quasi-static ball shear test is simulated at 30°C with a prescribed displacement rate of 0.5mm/min. Results show that steep stress gradients develop in the shear tool-solder contact and solder/IMC interface regions indicating effective load transfer to the interface. The bending (normal) stress is found to be of the same order of magnitude as the maximum shear stress. Higher stress values are predicted near the leading edge of the solder/IMC interface. The equivalent shear stress condition to the triaxial stress state at the interface, represented by the absolute maximum shear stress, τmax,abs should have reached the shear strength of the interface at fracture. The resulting shear strength of Sn40Pb/Ni3Sn4 interface is determined to be 87.5 MPa
Determination of energy consumption during turning of hardened stainless steel using resultant cutting force
No full textDownsizing energy consumption during the machining of metals is vital for sustainable manufacturing. As a prerequisite, energy consumption should be determined, through direct or indirect measurement. The manufacturing process of interest is the finish turning which has been explored to generate (near) net shapes, particularly for hardened steels. In this paper, we propose using measured cutting forces to calculate the electrical energy consumption during the finish turning process of metals where typically the depth of cut is lower than the cutting tool nose radius. In this approach, the resultant cutting force should be used for calculating the energy consumption, instead of only the main (tangential) cutting force as used in the conventional approach. A case study was carried out where a hardened stainless steel (AISI 420, hardness of 47–48 HRC) was turned using a coated carbide tool, with a nose radius of 0.8 mm, without cutting fluid, and at 0.4 mm depth of cut. The experimental design varied the cutting speed (100, 130, and 170 m/min) and feed (0.10, 0.125, and 0.16 mm) while other parameters were kept constant. The results indicate that the electrical energy consumption during the particular dry turning of hardened steel can be calculated using cutting force data as proposed. This generally means machining studies that measure cutting forces can also present energy consumption during the finish or hard turning of metals, without specifically measuring the power consumption of the machining process. For this particular dry turning of hardened stainless steel, cutting parameters optimization in terms of machining responses (i.e., low surface roughness, long tool life, low cutting force, and low energy consumption) was also determined to provide an insight on how energy consumption can be integrated with other machining responses towards sustainable machining process of metals
Strain Distribution Equal Channel Angular Pressing of Magnesium alloy at 90° and 120° Corner Angles
No full textAbstractSevere plastic deformation (SPD) is capable of producing metals with ultrafine grained microstructure. Equal channel angular pressing (ECAP) is a type of SPD process and is the focus of this study. The process was simulated using finite element analysis at different channel angles of 90° and 120°. The input for material properties, loads, velocities, boundary conditions and contacts were assigned to the finite element models to simulate the process. The strain distribution value were be obtained from the finite element analysis to determine the effect of the channel angle to the magnesium alloys AZ80 sample. The result shows that when the channel angle was 120°, the strain was lower but the concentrated stress at the corner region of the channel also lowers compared to when the channel angle was 90°. At any channel angle, presence of corner radius lowers the strain and the stress
Effects of starter defect on energy release rate of three-point end-notch flexure tested unidirectional carbon fiber reinforced polymer composite
No full textThe mechanics of damage and fracture process in unidirectional carbon fiber reinforced polymer (CFRP) composites subjected to shear loading (Mode II) were examined using the experimental method of the three-point end-notch flexure (3ENF) test. The CFRP composite consists of [0°]16 with an insert film in the middle plane for a starter defect. A 3ENF test sample with a span of 50 mm and interface delamination crack length of 12.5 mm was tested to yield the load vs. deformation response. A sudden load drop observed at maximum force value indicates the onset of delamination crack propagation. The results are used to extract the energy release rate, GIIC, of the laminates with an insert film starter defect. The effect of the starter defect on the magnitude of GIIC was examined using the CFRP composite sample with a Mode II delamination pre-crack. The higher magnitude of GIIC for the sample with insert film starter defect was attributed to the initial straight geometry of the notch/interface crack and the toughness of the resin at the notch front of the fabricated film insert. The fractured sample was examined using a micro-computerized tomography scanner to establish the shape of the internal delamination crack front. Results revealed that the interface delamination propagated in a non-uniform manner, leaving a curved-shaped crack profile
