Fixture Device Research Articles

Feasibility study of nonlinear ultrasonic imaging using a contact pulse-echo method for fatigue damage evaluation

ABSTRACT A contact pulse-echo nonlinear imaging method is proposed for the detection and localisation of fatigue damage in solid materials. A dual element transducer is designed based on nonlinear wave simulations and manufactured to improve the signal-to-noise ratio of harmonic waves. The transducer is clamped on a fixture device for scanning. The proposed method is introduced for scanning and imaging stainless steel specimens with different fatigue damage states. Experimental results for the specimen in the initial state show that both the fundamental and second harmonic waves are well measured and the imaging of nonlinear parameters is very stable over the scanning area. The imaging results for the specimen with an initial fatigue crack show that the fundamental waves remain the same but the second harmonic waves vary significantly in the potential growth area of the fatigue crack. Furthermore, the imaging results for the seriously fatigued specimen show that the amplitudes of fundamental waves decrease near the fatigue crack, while the amplitudes of second harmonic waves increase. These results indicate that the proposed pulse-echo method is effective for nonlinear ultrasonic imaging and early damage evaluation. The factors affecting the nonlinear waves in the lab experiments and possible problems with practical applications are also discussed for the proposed method.

Continuous Vertical Inside-Out Versus Traditional Vertical Inside-Out Meniscal Repair: A Biomechanical Comparison.

Biomechanical assessment of meniscal repairs is essential for evaluating different meniscal suturing methods and techniques. The continuous meniscal suture technique is a newer method of meniscal repair that may have biomechanical differences compared with traditional techniques. To evaluate the displacement, stiffness after cyclical loading, and load to failure for a continuous vertical inside-out meniscal suture versus a traditional vertical inside-out meniscal suture in a porcine medial meniscus. Controlled laboratory study. A total of 28 porcine knees were acquired and divided into 2 test groups of 14 medial meniscus each. A 2.0-cm longitudinal red-white zone cut was made in the body of the medial meniscus for each knee. The continuous suture (CS) group received 4 vertical stitches performed with a continuous vertical meniscal suture technique, and the inside-out suture (IO) group received a traditional vertical suture with 4 stitches. Two traction tapes were passed between the sutures and positioned in the biomechanical testing fixture device. Each specimen underwent load-to-failure testing at 5 mm/s, and displacement, system stiffness, and maximum load to failure were compared between the groups. The displacement after the cyclic test was 0.53 ± 0.12 and 0.48 ± 0.07 mm for the CS and IO groups, respectively. There was no significant difference between the groups (P = .2792). The stiffness at the ultimate load testing was 36.3 ± 1.9 and 35.3 ± 2.4 N/mm for groups CS and IO, respectively, with no significant difference between the groups (P = .2557). In the load-to-failure test, the ultimate load was 218.2 ± 63.9 and 238.3 ± 71.3 N in the CS and IO groups, respectively, with no significant group differences (P = .3062). A continuous vertical meniscal suture created a configuration for treating longitudinal meniscal lesions that was beneficial and biomechanically similar to a traditional vertical suture technique. The study findings indicate that use of the continuous vertical inside-out meniscal suture technique is a possible therapeutic option.

Liquid Moisture Transport in Stretched Knitted Fabrics

Abstract Transport of moisture is an important aspect of physiological comfort of clothing usage. The moisture originating from sweat can be in the form of vapour or liquid. Sweat in the form of liquid occurs, whereas the sweat in the form of vapour cannot be efficiently evaporated to the environment. For the stretchable fabrics, it is important to know the influence of stretching on their liquid moisture transport performance. The aim of the present work was to analyse the liquid moisture transport in knitted fabrics at varying degrees of stretch: 0, 15, 20 and 20%, and to assess the effect of stretch ratio on the ability of fabrics to transport the liquid moisture. Measurement was done using the M290 Moisture Management Tester supplemented with the MMT Stretch Fabric Fixture device. The obtained results confirmed that the stretching influences the values of the parameters characterizing the knitted fabrics from the point of view of their ability to transport liquid moisture.

SIMJig - Smart Independent Minimalist Jig

One of the most crucial parts of manufacturing is fixing the workpiece. Proper fixturing enables accurate machining, assembly, etching, etc. Most modern fixturing devices are static and difficult to adapt to varying workpieces. This letter introduces a new concept for a fixturing device–the SIMJig–that automatically adapts its structure to fix a given workpiece. Custom fitting the jig clamps to a workpiece can greatly improve the stability and accuracy of the manufacturing process. Reconfigurability is achieved by a unique clamp and gear design, as well as one of two optional external driving mechanisms. In total, the SIMJig only uses three actuators to control multiple clamps. The design of the SIMJig, as well as the two external drivers, are fully detailed. The method of operation is described, along with explanations of how the SIMJig is initialized. Two algorithms are presented that detail how the clamp configuration is derived from the workpiece model, and how the SIMJig derives the optimal reconfiguration scheme to achieve the clamp configuration. The SIMJig doubles as a turntable, which allows it to collaborate with robotic arms to vastly increase their workspace. This is illustrated for a notoriously difficult task of gasket insertion, using the SIMJig and two robotic arms.

Effect of dwelling time and plunge depth on the joint properties of the dissimilar friction stir spot welded aluminum and steel

Sound joints of a far apart property, pure aluminum and mild steel, dissimilar materials were obtained by friction stir spot welding (FSSW) solid state joining process. Sheets of 2 mm thickness were overlapped and fixed with a fixture device then welded. Welding parameters that produced the sound joint were identified. Joints microstructure and mechanical properties were investigated. A microstructural investigation has revealed a creation of mechanical interlocking and discontinuous formation of the intermetallic compounds found at the interface. The intermetallic compound (IMC) layer thickness ranged from 6 μm to 17 μm with the optimum condition specimen, 800 rpm and 5 Sec dwell time. Tensile–shear test showed that failure load has increased with increasing tool plunge depth and rotational speed. After the optimum value of rotational speed, the shear failure load decreased. The maximum shear failure load of 2.15 KN attained at 800 rpm and 2.4 mm plunge depth.

Design of Fixture for Welding

Defects commonly found in welding include distortion, overlapping, warping, and misalignment. Welders probably observe more frequent problems as such if lacking proper fixturing devices. Existing fixture designs are tedious to use, and they could induce even more defects. In this study, four design alternatives of a welding fixture were initially conceptualized from a survey of 25 experienced welders before the best one was selected based on reliability, rigidity, and ease of use. The design was made of SS400 steel because of its exceptional mechanical and thermal properties. A structural analysis was performed using the finite element method to evaluate the strength and stability of the design while in use. Experimental results revealed that this fixturing device could withstand forces exerted vertically from screw clamping. It could also tolerate high temperature from a welding arc and restrain the workpiece as deformed by the heat. This novel design will minimize set-up time, chances of defect formation, and a need for post-welding quality improvement.

Use of combined linear and nonlinear ultrasound to examine microstructural and microchemical variations in highly irradiated 304 stainless steel

This research combines linear and nonlinear ultrasound to examine the microstructural and microchemical changes in five large, highly irradiated cold-worked ANSI 304 stainless steel coin specimens cut from two hexagonal cross section blocks with radiation damage levels ranging from ~0.4 to ~33 dpa following irradiation in the EBR-II fast reactor. Both linear (velocity) and nonlinear ultrasonic (β) measurements were conducted in a hot cell using an automated fixture device specially designed to hold the sensor for repeatable measurements in an environment where direct human access is limited, demonstrating their potential to more fully investigate the complex defect ensemble introduced by irradiation. The measurements were performed at the Westinghouse Churchill site hot cell facility.The linear measurements agree very well with previous measurements employing a different sensor application technique. The ultrasonic nonlinearity parameters measured after irradiation increased by more than 100% from the unirradiated state and show a level of random variation below 4.7%. These ultrasonic nonlinearity parameters also show a spatial dependence on measurement location across each of the specimens in agreement with the spatial inhomogeneity of microstructure and microchemical distribution previously observed in adjacent, nominally identical specimens using transmission electron microscopy (TEM) and atom probe tomography (APT). It is proposed that the inhomogeneous distribution of microstructural and microchemical features including Frank loops, and both intragranular and grain boundary precipitates, as well as their different nonlinearity generation efficiencies are responsible for the spatial dependence of the measured ultrasonic nonlinearity parameters. The major and dominant component of the microstructure of these specimens at 20–30 dpa is vacancy agglomerations called voids, previously observed by microscopy and measurable using either linear ultrasonic velocity or linear attenuation, but which are not readily visible using nonlinear ultrasound. Components such as Frank loops, which are one of the other major microstructural components, do not contribute significantly to changing the linear ultrasonic velocity. Using this combination of linear and nonlinear measurements allows for the examination of microstructural/microchemical components whose linear ultrasonic interactions are overshadowed by voids, especially Frank loops and various radiation-induced precipitates.The changes in ultrasonic nonlinearity parameters in these specimens are thought to arise from two major sources. The smaller contribution is due to carbide pinning of dislocations in the grain boundary walls and the few line dislocations present in the grain interior. The largest contribution appears to come from segregation of Ni and Si to the perimeter of the very high density of Frank loops, leading to the formation of Ni3Si precipitates which are thought to be very efficient at pinning the Frank loops. These results on two hex blocks provide an ideal, though not completely realistic, test case to demonstrate the sensitivity of nonlinear ultrasound to two different microstructure sources.

Design and Manufacturing of a Turning Table for Polishing Tanks in Beer Industry

Abstract The main objective of this paper was to design and manufacture a turning table for fixing conical and tori spherical heads used for tanks in beer industry, to polish the surfaces and to obtain better quality and roughness. The turning table is an indispensable fixture device in the polishing process for vessel heads, where the accuracy and the roughness of the surface is an important factor because it can influence the quality of the beer. If the surface is smooth, the microbes and bacteria cannot be deposited on the tanks’ surfaces and also a good quality of the tanks’ walls prevent contamination in the beer composition. The research were made in Inotec Company, Romania. The new proposed design for the turning table improved the actual technology and reduced the manufacturing time. The tests made on the obtained manufactured products using the rotary table showed that the surface quality was improved too.

Fatigue properties of steel to aluminum transition joints produced by explosion welding

This manuscript presents the results of designing and testing a novel fixturing device for determining the fatigue properties of explosive bonded metals. The fatigue strength of steel to aluminum transition joints in tensile and compression stresses are presented. Additionally, shear stress for different load ratios was also studied. The stress distribution in the specimens was verified by finite element analysis. The experimental tensile/compressive fatigue results show a comparable fatigue lifetime to the recommended IIW values. The shear fatigue strength of the explosion-welded junction tested in this study is equivalent to a traditional butt welded joint.

Optimization of dip-coating methods for the fabrication of coated microneedles for drug delivery

As an approach of transdermal drug delivery, coated microneedles (MNs) have received extensive attention. Dip-coating method is a commonly used method in the preparation of coated MNs, due to its simple fabrication process and low cost. In this work, we proposed four different coating methods based on the dip-coating process, including dip-coating with a dam board, a roller, a fixture and a limit. The drug loading of the single MN prepared from the four methods was not significant (p > 0.05), from 15 to 16 ng. The minimum deviation of drug loading achieved 12.3% from the fixture device method. The in vitro drug delivery was also evaluated and the results revealed that the MNs fabricated from all methods could achieve about 90% drug delivery efficiency. All the results demonstrated that the dip-coating with a fixture method could guarantee a better homogeneous drug loading, which may be potential for future large-scale production of drug coated MNs.

Experimental and Numerical Investigation on Power Characteristics of 300 W Class Horizontal Axis Wind Turbine with Wave Winding Type AFPM Generator

This paper focuses on the power characteristics of a 300 W class horizontal axis wind turbine (HAWT) equipped with wave winding type axial flux permanent magnet (AFPM) generator. The small HAWT of this study is downwind type and installed with three high speed blades. Structural design for AFPM generator and wind turbine is carried out, and a fixture device for AFPM generator is developed. The developed AFPM generator is direct drive type and its basic performances are evaluated through no-load and load test. A wind tunnel test of the small HAWT equipped with wave winding type AFPM generator is conducted and the electrical power of the developed wind turbine is calculated. Also, based on the detailed design of the new small HAWT, CFD analysis is performed to calculate the mechanical power. Finally, the numerical power and the experimental power of the developed small HAWT are compared. The maximum coefficient of power of the HAWT is 0.34 at 6.7 m/s due to the application of the new wave winding type AFPM generator.

Performance Evaluation of a Low Cost Creep Testing Machine

Mechanical systems and components like steam generators or boilers, nuclear reactors, turbine rotors are operated at very high temperature under significant stress. For this reason, the components and structures need to be designed so that excessive creep distortion must not occur within the expected operating life of the system. Creep is defined as a time-dependent deformation that happens when metals are subjected to constant load at high temperature over a period of time. Knowledge of the creep behavior of metals is therefore important and for this reason Creep testing machines are predominantly used to measure how a given material will perform under constant load, at elevated temperature. This paper aims to study creep properties of various materials being used in high temperature applications through locally made creep testing machine. The basic design of a creep testing machine is the support structure, the loading device, the fixture device (grips and pull rods), and the furnace. The specimen being tested is held in place by the grips and a furnace surrounds the test section and maintains a constant temperature. Maximum applied load on the specimen can be 15 kg and tests could be carried out at maximum temperature of 500°C. Creep curves of strain versus time of aluminum alloy were plotted at a different stress level and temperature. The data are plotted in a simple manner, but analysis easily shows the effect of increased stress due the reduction in specimen cross-section as strain increases. The creep testing machine developed in this work has proven to be satisfactory, cost effective and good alternative to imported creep testing machine.

The Influence of Clamping Pressure on Joint Formation and Mechanical Performance of Ti6Al4V/CF-PEEK Friction-Riveted Joints.

This work aims at investigating the influence of pre-set clamping pressure on the joint formation and mechanical strength of overlapping direct-friction-riveted joints. A pneumatic fixture device was developed for this work, with clamping pressure varying from 0.2 MPa to 0.6 MPa. A case study on overlapping joints using Ti6Al4V rivets and woven carbon fiber-reinforced polyether-ether-ketone (CF-PEEK) parts were produced. Digital image correlation and microscopy revealed the expected compressive behavior of the clamping system and the continuous pressure release upon the joining process owing to the rivet plastic deformation and the polymer squeezing flow. Two preferential paths of material flow were identified through the alternate replacement of the upper and lower composite parts by a poly-methyl-methacrylate (PMMA) plate—the composite upward and squeezing flow between the parts which induced their separation. The ultimate lap shear forces up to 6580 ± 383 N were achieved for the direct-friction-riveted CF-PEEK overlap joints. The formation of a gap to accommodate squeezed polymer between the composite parts during the process had no influence on the joint mechanical performance. The increase in the clamping pressure for joints produced with a low friction force did not affect the joint-anchoring efficiency and consequently the joint strength. On the other hand, the combined effect of a high-friction force and clamping pressure induced the inverted bell shape of the plastically deformed rivet tip, a lower anchoring efficiency, and the delamination of the composite, all of which decrease the mechanical strength by 31%. Therefore, the higher the friction force and clamping pressure, the more defects would be generated in the composite parts and the more changes in the shape of the plastically deformed rivet tip, leading to a lower level of quasi-static mechanical performance. All the joints failed by initial bearing of the composite and final rivet pull-out. The findings of this work can contribute to further improvement of the clamping design for industrial application.

Large - scale Rectangular Ruler Automated Verification Device

This paper introduces a large-scale rectangular ruler automated verification device, which consists of photoelectric autocollimator and self-designed mechanical drive car and data automatic acquisition system. The design of mechanical structure part of the device refer to optical axis design, drive part, fixture device and wheel design. The design of control system of the device refer to hardware design and software design, and the hardware mainly uses singlechip system, and the software design is the process of the photoelectric autocollimator and the automatic data acquisition process. This devices can automated achieve vertical measurement data. The reliability of the device is verified by experimental comparison. The conclusion meets the requirement of the right angle test procedure.

An approach to support entries for a design failure modes and effects analysis

The design of a fixture device is very laborious, requiring consideration of many issues from series production, information on the raw part material, required precision surfaces, ensuring an appropriate orientation scheme, continue with requirements related device itself as number of parts, parts type, complexity, manageability, easy operation and maintenance. That is why realising a proper analyse regarding the possible failures associated to these issues is overwhelming. This paper’s aim is to propose an approach for collection of items necessary for starting a Design FMEA, using Functional Analysis, TRIZ functional modelling and axiomatic design approaches. The proposed approach – to extract items for a FMEA analyse – is applied to an example of an expanding mandrel regarding its internal components and theirs relations in order to accomplish the main requirement: the accurate locating and clamping of a part.

Oblique Terminal Screw Placement: Does It Improve Fixation in Plate Osteosynthesis?

The technique of placing an oblique screw in the terminal hole of a plate to increase screw pullout strength is widely taught in the operating room. The origin of this technique is unclear; however, it may have been used simply as a means to identify radiographs and misinterpreted to have some biomechanical benefit. The objective of this study was to measure the structural effect of oblique terminal screw placement (OTSP) during plate osteosynthesis. Foam blocks and limited contact dynamic compression plates and screws were used along with a custom fixture device. The terminal screw was placed in either an oblique (30-degree angle outward) or perpendicular fashion. A load was applied perpendicular to the plate in cantilever bending until failure. The oblique screw construct was significantly weaker than the perpendicular screw construct (399N vs. 465N, P < 0.001), independent of the block of material used. Post hoc analysis showed that the screw angle (P < 0.001) was a significant determinant of the load required to cause screw pullout. OTSP led to a decrease in pullout strength compared with a perpendicular screw in a deformable foam medium similar in density to osteoporotic bone. In patients with poor bone quality, OTSP may create a suboptimal fracture fixation construct.

Design and Testing of a Highly Reconfigurable Fixture With Lockable Robotic Arms

The paper describes an innovative fixture created within the AUTORECON project of the European Commission's 7th Framework Program. The fixture is designed to respond to the automotive industry's needs of high modularity and full flexibility, by allowing the secure multishape grasping of a very wide range of (often large and heavy) metal workpieces typical for car-assembly operations. The fixture is used as an end-effector of an industrial robot, which in turn acts in cooperation with other machines, such as other robots performing machining or other processes on the part. The fixturing device is both a highly reconfigurable structure and a robotic mechanism: moving as a programmable robot to reconfigure and acting as a supporting structure once a hold on the part has been established. This dual functioning has been made possible by the development of a key component, a stepless lockable revolute joint, described herein. In order to get a readily modifiable system, all parts of the fixture are designed as modules. Prototypes of the main parts and the whole fixture have been fabricated and experiments validating the design are reported.

The Design of Turn-Mill Process Planning for Mass Customization Wheel Rim

Targeted at numerical control machining process of mass customization vehicle wheel rim revolving body parts and its fixture planning problem, using the dot product method between the unit normal vector of the feature facet, it was provide to distinguish the main direction of machining surface, machining position of workpiece was determined, and NC machining process of integrated procedure was designed. The loaded and taken out of the wheel rim workpiece were analyzed according to the two-dimensional plane clamping method, the clamping point position of wheel rim workpiece can be determined. Using the principle of planar mechanism kinematic to analyze one’s claw of turn-mill fixture kinematics trace, so that a quick clamping structure can reduce the cylinder stroke was designed. This fixture device was convenient and reliable.

Influence of the engagement ratio on the shear strength of an epoxy adhesive by push-out tests on pin-and-collar joints: Part II: Campaign at different temperature levels

Previous research led to the conclusion that the Engagement Ratio (i.e. the coupling length over the coupling diameter, ER) does not significantly affect the shear strength of an anaerobic adhesive (LOCTITE 648). Conversely, ER is effective on the response of an epoxy adhesive (LOCTITE 9466), with a beneficial effect for ER>1. The aforementioned campaigns have been performed at room temperature, whereas, the effect of ER combined to that of temperature is still unexplored. The subject of this paper consists in the experimental investigation of the impact of ER on the strength of LOCTITE 9466 at higher temperatures. Decoupling tests have been performed, considering three levels of temperature (40°C, 60°C and 80°C). Pin-and-Collar samples have been prepared, considering four levels of ER. A fixture device has been designed, to prevent misalignments and to reduce heat dissipation during the pushing-out phase.The statistical processing of the data led to the conclusion that ER retains its effectiveness up to the temperature of 40°C with strength enhancement for ER beyond 1. Conversely, at the highest levels of temperature, a strength drop to approximately 44% occurs, and the effect of ER is no longer significant to compensate this decrease. Moreover, a highly significant negative interaction was detected between ER and temperature.

Determination of the Milling Conditions of a Pump Casing Cover Using a Parametric Designed Fixture Device

This paper presents an applicative methodology of parametric computer aided design using the CATIA v5 software to model and assembly a modular fixture device. The device is then used in the orientation and clamping a part of type casing cover which has a face machined by milling. Having a constructive solution of the fixture device, the next step is to simulate a milling process through a FEM analysis to identify the working conditions: milling tool diameter, number of teeth, cutting forces, required power of the machine tool etc. Some parameters were chosen according to various tools manufacturers catalogues and the cutting force components were determined experimentally in laboratory conditions. The analysis results show that in the FEM simulated milling process, in all the fixture device parts, some tensions cause displacements that have an influence over the casing cover surface roughness.