Test Jig Research Articles

Cost-effective and innovative test jig for fishing-bait release mechanisms attached to drones

Cost-effective and innovative test jig for fishing-bait release mechanisms attached to drones

Method to estimate rotational stiffness: Trial masses, virtual masses, and virtual springs

This paper proposes a method to estimate the rotational stiffness at the coupled points of an assembled system. Conventional test-based rotational stiffness evaluation methods are sensitive to measurement errors and require a separate jig for testing. In contrast, as the proposed method uses the natural frequency shift phenomenon resulting from the addition of mass, the measurement error is relatively small, and accuracy is improved by excluding the interference of other modes. The proposed method also solves the complexity of the conventional method by changing the fixed condition of the system using frequency response function-based substructuring modeling; consequently, it does not require a dedicated jig for fixing. In this process, the concepts of trial mass, virtual mass, and virtual spring are introduced to systematically explain the proposed method and applied to the method using frequency shift. The results of experiments conducted on a vehicle shock absorber verify the utility of the proposed method.

Performance of Withdrawal Capacity for Mengkulang Glulam Perpendicular to the Glue Line for 14mm and 20mm Bolt Diameter

Withdrawal capacity is defined as the amount of resistance to withdrawal force in a plane normal to the surface panel. It is caused by density and internal bonding of the panel. Withdrawal capacity is one of the factors that affect the load carrying capacity of the timber connection apart from embedment strength and fastener yield moment. The European Yield Model (EYM) theory is used to predict the load capacity of the timber connection under lateral load. The sample panel is made of Glued Laminated Timber (Glulam) using Mengkulang timber species. Although Mengkulang Glulam has a good weight to strength ratio as compared to typical concrete material but it is still not widely used in Malaysia. This is mainly due to a very limited exposure on the Mengkulang Glulam usage. Withdrawal capacity is determined according to the ASTM D1761-12 using one-hole test method. Also, the ASTM D1761-12, EC5:2008 is used to determine the withdrawal capacity output. In this experiment a mechanical fastener, bolt; 14mm and 20mm were used to fix the sample panels onto the test jig. The bolt diameter influenced the withdrawal capacity. It was observed that the withdrawal capacity of 20mm bolt diameter was better than the 14mm diameter with an increment of 48.6%.

Modeling of Fatigue-Strength Development in Cold-Emulsion Asphalt Mixtures Using Maturity Method

Emulsion asphalts are cost-effective, environmentally friendly, and sustainable alternatives to hot-mix asphalts. Laboratory curing protocols currently used to simulate field curing of emulsion asphalts have been observed to offer conflicting predictions. This study employed the maturity method to account for the combined effects of temperature and time on fatigue-strength development in emulsion asphalts. An emulsion asphalt, composed of 55% reclaimed asphalt pavement, 45% virgin aggregates, 6.2% bitumen emulsion, and 4% pre-mix water was designed following the Asphalt Institute procedure. A total of 168 specimens from the mix were variously cured at 5 °C, 25 °C, 40 °C, and 50 °C for time intervals of 1, 3, 5, 7, 14, 21, and 28 days, before being tested for fatigue-strengths on the four-point bending test jig. It was observed that fatigue-strengths increased with an increase in cure temperature but decreased with an increase in cure duration. A parabolic hyperbolic fatigue-maturity model was developed from results of specimens cured at 5 °C, 25 °C, and 40 °C and validated with results from specimens cured at 50 °C. A strong correlation was observed between predicted fatigue-maturity and laboratory-determined fatigue-strengths at test strain levels between 125 µm/m and 200 µm/m. The study concluded that the laboratory characterization of emulsion asphalts should consider the curing history of the mix.

Investigation of the safety evaluation method of piping system

Plumbing is necessary for boilers and heat exchangers and in buildings and power plants, including those that produce green energy. Further, among all the components used in plumbing, piping systems are subjected to high temperatures and pressures. A twisted or cracked pipe adversely affects the efficiency of a power plant and production rate of a factory or causes secondary accidents. This study investigates the safety evaluation of the SUS material, which is mainly used in boiler and heat exchanger piping. SUS is an inelastic material; therefore, the leak-before-break concept of fracture mechanics, for which various safety evaluation methods and specifications have been presented, can be applied during the design stage. However, the test is performed as a substitute for the actual pipe testing because of the high cost and difficulty level. Thus, a method to test compact pipes based on various loading ratios is developed. This study determines the test jig shape to obtain fragility similar to the theoretical value. The proposed test method is only available under certain load conditions and requires a new J-integral when the jig geometry or load ratio is changed. Therefore, the J-integral equation for each load condition is integrated to propose a J-integral equation independent of the load ratio.

Signal amplification with patterned conducting polymer electrodes based organic thin film transistor circuit

Organic thin film transistors (OTFTs) fabricated with non-destructive patterning techniques are the building blocks in realizing flexible electronic interface for sensing applications. In this study, a single stage differential amplifier is demonstrated with flexible OTFTs. The OTFTs were fabricated with thermally evaporated Pentacene as the semiconducting layer. The electrodes of the OTFTs were realized using a conductive polymer composite, poyaniline:polystyrene sulphonic acid (PANi-PSS), patterned by a modified Parylene lift-off process. Electrical characteristics of bottom contact TFTs with polymeric PANi-PSS electrodes is superior to those with conventional metal electrodes due to a lower charge injection barrier and resultant lower contact resistance. The measurement of the transistor characteristics and the amplifier response reported has been carried out with a wafer probing test jig set up. The differential amplifier realized with p-type Pentacene transistors with mobility, 0.5 cm2/Vs, exhibited a voltage gain of 10 dB in a frequency bandwidth of 1 kHz.

Design and development of ring-on-ring jig for biaxial strength testing of brittle ceramic composite materials: ZrB2-30wt-%SiB6

ABSTRACTThe strength of brittle ceramic materials is typically tested using simple uniaxial compression or by three- or four-point bending techniques. While these methods provide reliable results, they do not depict a realistic characterisation of the load-bearing capacity of structural materials, and a method that involves the application of multiaxial stress is required, such as the ring-on-ring biaxial flexural strength test. In this paper, an in-house ring-on-ring fixture was developed and validated by comparing the experimental and simulated biaxial strength tests of a model ZrB2-30wt-%SiB6 ceramic composite. A description of the simulated finite element analysis is provided, and the stress field acting on the sample with maximum principal stress located at the surface under tension at the centre of the ceramic disk is shown.

An Investigation of the Structural Strength of Transtibial Sockets Fabricated Using Conventional Methods and Rapid Prototyping Techniques.

Rapid Prototyping is becoming an accessible manufacturing method but before clinical adoption can occur, the safety of treatments needs to be established. Previous studies have evaluated the static strength of traditional sockets using ultimate strength testing protocols outlined by the International Organization for Standardization (ISO). To carry out a pilot test in which 3D printed sockets will be compared to traditionally fabricated sockets, by applying a static ultimate strength test. 36 sockets were made from a mold of a transtibial socket shape,18 for cushion liners with a distal socket attachment block and 18 for locking liners with a distal 4-hole pattern. Of the 18 sockets, 6 were thermoplastic, 6 laminated composites & 6 3D printed Polylactic Acid. Sockets were aligned in standard bench alignment and placed in a testing jig that applied forces simulating individuals of different weight putting force through the socket both early and late in the stance phase. Ultimate strength tests were conducted in these conditions. If a setup passed the ultimate strength test, load was applied until failure. All sockets made for cushion liners passed the strength tests, however failure levels and methods varied. For early stance, thermoplastic sockets yielded, laminated sockets cracked posteriorly, and 3D printed socket broke circumferentially. For late stance, 2/3 of the sockets failed at the pylon. Sockets made for locking liners passed the ultimate strength tests early in stance phase, however, none of the sockets passed for forces late in stance phase, all broke around the lock mechanism. Thermoplastic, laminated and 3D printed sockets made for cushion liners passed the ultimate strength test protocol outlined by the ISO for forces applied statically in gait. This provides initial evidence that 3D printed sockets are statically safe to use on patients and quantifies the static strength of laminated and thermoplastic sockets. However, all set-ups of sockets made for locking liners failed at terminal stance. While further work is needed, this suggests that the distal reinforcement for thermoplastic, laminated and 3D printed sockets with distal cylindrical locks may need to be reconsidered.

Influence of plate type and placement on the immobilization of bilateral equine mandibular osteotomies: Ex vivo study.

To determine the influence of plate fixation (locking or dynamic compression) and the site of application (ventral [V] or ventrolateral [VL]) on the resistance to bending of transverse mandibular fractures. Ex vivo, simple randomized study. Mandibles harvested from adult equine cadavers (n = 18). Bilateral osteotomies were created 1 cm caudal to the mental foramen and perpendicular to the long axis of each mandible. Mandibles were fixed with 1 of 3 methods: (1) VL dynamic compression plate (DCP), (2) V-DCP, or (3) VL locking compression plating (LCP). Constructs were mounted on a custom testing jig and tested for resistance in bending by applying force to the rostral aspect of the mandible. Stiffness and change of distance of the dorsal osteotomy at 200 N were compared among constructs. VL-LCP constructs were 5.25 and 2.42 times stiffer than V and VL constructs, respectively (P<.001). Change in the width of the osteotomy gap at 200 N of load was reduced 6.04 times when osteotomies were stabilized with VL compared to V (P<.001); no difference was detected between the VL and VL-LCP constructs (P=.836). Ventrolateral LCP fixation of equine transverse mandibular osteotomies provided greater resistance to bending compared with V and VL constructs. These results provide evidence to recommend fixation of transverse interdental mandibular fractures with VL-LCP rather than with DCP in horses.

A preclinical method for evaluating the kinematics of knee prostheses

The primary intent of anatomical knee implants is to replicate the motions of a normal knee joint. In developing such designs, a preclinical evaluation of kinematic behavior is needed. This study introduces an in vitro testing method for recording movements of the knee joint. A novel testing jig was developed and incorporated into a knee simulator setup alongside a motion capture system to directly track the medial and lateral movements of a knee prosthesis. The test system developed in this study required a number of factors to be validated; (i) gait inputs to the knee simulator (result: 0.37–1.575% error), (ii) validity of global coordinate system in the motion capture system, (iii) the position of flexion facet centers (FFCs) detected by the motion capture system (result: a maximum error of 0.08 mm in AP direction and 0.3 mm in SI direction), (iv) local coordinate system in the motion capture system (result: 1.09% error for the measurement of flexion angle), (v) that FFC results were in good agreement with inputs. In conclusion, the system developed in this study for recording FFC is a direct and reliable in vitro test method for analyzing the kinematics of a knee prosthesis.

The effect of the mandibular plane angle on fracture line stability: An ex vivo experimental study.

Mandibular angle fractures fixated with plate osteosynthesis techniques have to withstand the effects of muscle attachments. Individual variations in the craniofacial morphology may alter the biomechanical resistance of the bone-plate construct. The aim of the present study was to determine the influence of variations in the mandibular plane angle (MPa) on the biomechanical stability of sheep mandibular angle fractures (MAFs). Sixty sheep hemi-mandibles were used. The mandibles were positioned on a test jig that simulated low (15°, group L), normal (25°, group N), and high (35°, group H) MPa. Unfavorable MAFs were created with thin diamond cutting disks. One four-hole, 9.0-mm-spacing, standard titanium miniplate of 2.0mm thickness and 5.0-mm-long screws were inserted at the superior border of the alveolar bone in monoplanar orientation. Specimens were then subjected to vertical loads between 10N and 150N in a universal testing machine. The displacement values at each 10N force increment and the load magnitude at which 3.0mm displacement limit was reached were recorded. Starting from 40N, the displacement values at each 10N increment in the H group were significantly higher than those of the L and N groups until 150N (P<0.05). The force magnitude required to reach 3.0mm of displacement in the H group was significantly lower than that for the L and N groups (P<0.05 for each). The one-miniplate monoplanar fixation technique used in sheep MAF with high MPa is more likely to offer lower biomechanical resistance to the vertical forces applied over the molar region than do the normal and low MPa.

A biomechanical study of headless compression screws versus a locking plate in radial head fracture fixation

Fixation of a 3-part radial head fracture with cannulated compression screws will show equivalent stiffness to a locking plate under axial load. Debate exists regarding the management of Mason type III fractures, with many believing that open reduction and internal fixation provides advantages over other options. By virtue of their subarticular placement, screw fixation is less likely to cause impingement compared with plate fixation, which can result in loss of rotation and requirement for hardware removal. Insufficient fixation stability can lead to nonunions, necrosis of the radial head, pain, and instability. We tested the mechanical stability of fixation of simulated radial head fractures using headless compression screws compared with standard plate construct. Standardized test constructs were created with repeatable osteotomy cuts and hardware placement on each Synbone model (Synbone AG, Malans, Switzerland). We presectioned 22 proximal radius Synbone models to simulate a 3-part radial head fracture. The models were fixed using a radial head locking plate or headless compression screws in a tripod construct. The constructs were potted into a compression test jig using 2-part epoxy resin. Compression testing was performed using a 30-kN Instron Universal machine (Instron, Norwood, MA, USA). The compression tool was spherical, representing the surface of the capitellum. There was no significant difference between the stiffness of the Synbone constructs under axial load. There was no significant difference between fixation stiffness of a 3-part radial head fracture with headless compression screws in a tripod structure vs. a locking plate in Synbone. Further study is required to allow clinical application.

Eccentric loading of a 25-m long composite column subjected to a combination of axial compression and transverse gravity loading using a horizontal test method

This article presents a feasibility study where fibre-reinforced structural elements are assembled into long slender columns using adhesive bonding. The columns are intended to be part of an externally guyed high-voltage transmission tower where they are subjected to a combination of compressive and transverse loads. The article has shown that 25-m long poles can be made with small tolerances in both angularity and concentricity. Previous published scientific work on buckling of composite columns was applied to predict the behaviour of the pole as it was being loaded in compression to 1200 kN or within 5% of its critical load in a bespoke horizontal test jig. The confidence in the material, the structural elements, the analysis method and the quality of the test equipment has shown that there is a potential in further optimization of the structure that will ultimately be a part of a high-voltage composite tower.

Development of Ring-End Crush Testing JIG of Glass Fiber Structure Sheet and Estimation of In-Plane Compressive Strength of that Sheet

Development of Ring-End Crush Testing JIG of Glass Fiber Structure Sheet and Estimation of In-Plane Compressive Strength of that Sheet

Biomechanical Study of Extensor Tendon Lacerations Over the Finger Metacarpophalangeal Joints

Purpose To assess the percentages of extensor tendon lacerations over the finger metacarpophalangeal (MCP) joints that may lead to an MCP joint extensor lag. Methods We obtained 8t fresh-frozen cadaveric hand specimens. The extensor and flexor tendons were isolated for simulated active extension and passive flexion. The specimens were secured to a testing jig. Sequential full-thickness, transverse cuts were made through the extensor tendons over each MCP joint. The fingers were cycled before and after each incremental tendon cut. Extensor tendon gaps were measured and inclinometer measurements of MCP joint rotation were used to determine MCP joint extensor lags. Results Incremental cuts of the extensor tendons caused sequential increases in subjacent MCP joint extensor lags in addition to interactive effects on other finger MCP joints. Extensor lags of the index and little finger MCP joints were statistically significant; lacerations extended across 75% or more of the combined widths of the extensor tendon slips. In comparison, extensor lags of the middle and ring finger MCP joints were statistically significant; lacerations involved 90% or more of the widths of the extensor tendons. A statistically significant MCP joint extensor lag in the index and little fingers was also observed when 1 of 2 extensor tendon slips in either finger was completely transected. Conclusions In this biomechanical study of extensor tendon lacerations over the finger MCP joints, we found that MCP joint extensor lags varied by both the finger involved and the percentage of tendon width damage. Additional work is needed to determine the clinical importance of MCP joint extensor lags of differing degrees. Clinical relevance Lacerations of extensor tendons overlying the finger MCP joints in clenched-fist to mouth injuries are typically repaired in a delayed fashion. An improved understanding of the relations between extensor tendon slip lacerations and MCP joint extensor lags may provide a basis for treatment algorithms that could potentially reduce the costs of care.

Screen printing for support-pillar placement for vacuum glazing and the effects of pillar spacing on strength properties

Maintaining a vacuum between the two glasses to maximize the heat insulating performance, it is indispensable to array the pillar for the vacuum glazing to maintain the vacuum gap. In this paper, to investigate the effect of the spacing of the pillars arranged using the screen printing method on the strength of the glass, a bending strength test was carried out by design and fabricating a ROR bending strength test jig based on the Euro standard. In the strength test results, the experimental results were analyzed using the Weibull distribution, which is a statistical analysis method mainly used for evaluating the breaking strength of brittle material. Based on the analysis results, the placement spacing of the pillars proved validity for maintaining the vacuum glass gaps.

Effect of plasma treatment on adhesion strength and moisture absorption characteristics between epoxy molding compound/silicon chip (EMC/chip) interface

Reliability of interface between two dissimilar materials becomes an important issue due to increasing demands of high-density integrated circuits. Most of failures of semiconductor package occur at the interface between two dissimilar materials in high temperature reflow process, thus, adhesion strength under high temperature should be investigated. In this study, an adhesion shear test jig was newly devised to measure the adhesion strength of epoxy molding compound/Si chip (EMC/chip) interface at high temperature (200 °C). In order to investigate the effect of plasma treatment on adhesion strength and moisture absorption characteristics, the number of plasma treatments was varied. Also, moisture absorption time was varied to observe the moisture uptake and degradation of adhesion strength with respect to plasma treatment number. Atomic force microscope (AFM) was analyzed to verify the surface roughness of silicon chip, and scanning electron microscopy (SEM) was used to observe cross-sectional fractured morphology after adhesion strength test. From this study, it was found that the plasma treatments affect much the adhesion strength and moisture uptake at the interface between the EMC/Chip interface.

Capacitance-voltage profiling of MOS capacitors: A case study of hands-on semiconductor testing for an undergraduate laboratory

Catering to a large undergraduate laboratory class requires the experiments to be robust, low maintenance, and easy to set up with low cost test equipment at the disposal of most university laboratories. Most introductory undergraduate semiconductor device laboratory courses utilize packaged semiconductor integrated circuit chips to illustrate the functioning and applications of fundamental semiconductor devices such as diodes and transistors. While such methods do justice to the illustration of device concepts, the packages abstract the device physics and manufacturing and promote a “black-box” mentality towards device engineering. We have proposed and implemented a novel undergraduate device laboratory experiment, where metal oxide semiconductor capacitor (MOSCAP) devices were designed and fabricated at our university cleanroom and provided to students to perform basic capacitance-voltage profile measurements. To allow over a hundred students to simultaneously perform the experiments, we fabricated miniature test jigs that served as probe stations with spring-loaded pogo pins to make electrical contact with the devices. Using a simple op-amp based circuit that is easy for second year undergraduates to analyze, students are able to successfully extract device parameters such as substrate doping density and flat-band voltage using this experiment, and visualize the different modes of operation of a MOSCAP.

Development of a 3D ultrasound guidance system for permanent breast seed implantation.

Permanent breast seed implantation (PBSI) is a promising radiotherapy technique for early-stage breast cancer, completed in a single visit by permanently implanting 103 Pd seeds using needles inserted through a template and guided by two-dimensional (2D) ultrasound (US). However, operator dependence has been highlighted as a limitation of this procedure. Consequently, we propose and have developed an intraoperative guidance system using three-dimensional (3D) US and an instrumented mechanical arm to provide intraoperative 3D imaging and needle template tracking. A mechatronic 3D US scanner reconstructs a 3D image from 150 2D images. A tracked mechanical arm mounted to the scanner locates four fiducial points on the template, registering the template to the 3D image. 3D reconstruction was validated for linear and volumetric measurement accuracy using phantoms of known geometry. In vivo breast US image quality was evaluated in a healthy volunteer. The encoded arm was calibrated and validated using a jig with divots at known locations relative to the scanner and the scanner registered to the 3D US image using intersecting strings in a fluid-filled test jig. Template registration accuracy was assessed using a machined test jig. Tracking accuracy was assessed in a liquid medium by comparing tracked and imaged needle tip positions. Finally, the system was used to guide a mock procedure in a patient-specific phantom and micro-CT imaging used to evaluate its accuracy. Geometric validation showed median distances within ±1.1% of expected values and volumetric validation showed differences of ≤4.1%. Tracking arm point measurements showed an average error of 0.43mm and 3D US volume registration showed target registration error ≤0.9mm. Mean template registration accuracy in each axis of translation/rotation was ≤1.3mm/1.0°. Mean needle-targeting error was 2.5mm and 1.6° for needle tips and trajectories, respectively. Mean needle tip and angular errors of the phantom procedure were 2.1mm and 2.6°. Modeled seed displacement of the phantom procedure showed mean error of 2.6mm and a maximum of 3.8mm. A 3D US guidance system for PBSI has been developed. Benchtop performance and image quality in volunteer scans are satisfactory. A phantom PBSI procedure was successfully delivered using the system with maximum seed error within dosimetric benchmarks (<5mm). Translation of the device into the clinic is forthcoming.

Pressure Distribution in the Ankle and Subtalar Joint With Routine and Oversized Foot Orthoses.

Foot orthoses are used to treat many disorders that affect the lower limb. These assistive devices have the potential to alter the forces, load distribution, and orientation within various joints in the foot and ankle. This study attempts to quantify the effects of orthoses on the intra-articular force distribution of the ankle and subtalar joint using a cadaveric testing jig to simulate weight bearing. Five lower-limb cadaveric specimens were placed on a custom jig, where a 334-N (75-lb) load was applied at the femoral head, and the foot was supported against a plate to simulate double-leg stance. Pressure-mapping sensors were inserted into the ankle and subtalar joint. Mean pressure, peak pressure, contact area, and center of force were measured in both the ankle and subtalar joints for barefoot and 2 medial foot orthosis conditions. The 2 orthosis conditions were performed using (1) a 1.5-cm-height wedge to simulate normal orthoses and (2) a 3-cm-height wedge to simulate oversized orthoses. The contact area experienced in the subtalar joint significantly decreased during 3-cm orthotic posting of the medial arch, but neither orthosis had a significant effect on the spatial mean pressure or peak pressure experienced in either joint. The use of an oversized orthosis could lead to a decrease in the contact area and alterations in the distribution of pressure within the subtalar joint. The use of inappropriate orthoses could negatively impact the force distribution in the lower limb.