Hole Exit Research Articles

Biology of broadbean seed beetle (Bruchus rufimanus; Coleoptera: Chrysomelidae) in Latvia

ABSTRACT The broadbean seed beetle (Bruchus rufimanus Boheman, 1833) is a major pest of faba bean (Vicia faba L.) almost everywhere this crop is grown. The main tasks of this research were to study the seed beetle's phenology, and rates of egg laying, larval survival and the emergence of young adults before the harvest. Studies were done in field conditions in farms located in various places in Latvia. The highest density of imagines was observed at a time when the plants were flowering intensively. Egg laying began as soon as the pods had formed in the lower third of the stem and lasted 4–5 weeks. In severe infestation happened, more than 34 eggs were laid per pod. The percentage of damaged yield increased in proportion to the average number of eggs laid on pods until this number reached 11–12 eggs per pod and remained at approximately the same level also when egg-laying rate was higher. In several fields, no seeds with imago exit holes were found in the samples few days before harvest, while in other sowings, the proportion of such seeds exceeded 90% of the total amount of damaged yield.

Convolutional Recurrent Neural Network to Determine Whether Dropping Slag Dart Fills the Exit Hole During Tapping in a Basic Oxygen Furnace

Convolutional Recurrent Neural Network to Determine Whether Dropping Slag Dart Fills the Exit Hole During Tapping in a Basic Oxygen Furnace

Surface roughness effects on film-cooling effectiveness in a fan-shaped cooling hole

Large eddy simulations (LES) were carried out to investigate the influence of surface roughness, which was applied to the inner walls of a cooling hole, on cooling performance and flow structures. The cooling hole was a 30-degree inclined, baseline 7-7-7 fan-shaped hole relative to a turbulent flat plate boundary layer of the mainstream. Numerical simulations were performed at two different blowing ratios (M=1.5 and 3.0) and at a constant density ratio (DR=1.5) for various configurations of surface roughness. In order to numerically consider the effects of surface roughness, the equivalent sand-grain roughness model was utilized. Different correlations between the equivalent sand-grain roughness height and arithmetic average roughness height were numerically tested to find an accurate correlation compared to the measurements. The time-averaged numerical results were validated by experiments looking at the velocity and thermal fields for the smooth and rough cooling holes. Results revealed that increasing the surface roughness applied to the cooling hole, increases the thickness of the boundary layers within the hole, especially at the higher blowing ratio. This leads to a higher jet core flow at the cooling hole exit and lower cooling effectiveness at the flat plate surface compared with a smooth cooling hole. The minimum area-averaged film-cooling performance showed a 58% reduction compared to a smooth hole in the case of the highest blowing ratio (M=3.0) and the largest surface roughness height. In addition, the time-space evaluation of the velocity fluctuations showed greater flow unsteadiness and increased wavy patterns within the cooling hole in the case of rough holes.

Phenotyping of Sorghum Lines for Resistance to African Stem Borer (Sesamia Calamistis)

Stem borer ( Sesamia calamistis ) is a serious insect pest of sorghum (Sorghum bicolor) resulting in grain yield losses ranging between 15-80%. However, genotypes showing complete resistance to these borers have not been identified in Nigeria. Utilization of resistant varieties in combination with other methods of control would offer a sustainable strategy for S. calamistis management in sorghum production. The objective of this study was to validate the acclaimed resistance in the materials received from Kenya and India in Nigerian environment and to screen and ascertain the status of some Nigerian Sorghum to Sesamia calamistis . Eighty-eight sorghum lines were artificially infested with the eggs of the stem borers at two different environment (Field and Screen House) using alpha-lattice design, consisting of 11 plots in eight blocks, replicated twice. Data were collected on leaf feeding, number of dead-hearts, cumulative stem tunnel length, number of exit holes, and selected agronomic traits. There were significant (p<0.01) differences among the test genotypes for all the traits measured. Based on the selection index, 15% of genotypes were categorized as resistant, 42% as moderately resistant,33 as moderately susceptible and 10% as susceptible.13 genotypes showed resistance across the environments (field and screen house): ICSB464, ICSL71086, SSV20041-2YELLOW, ICSL71018, ICSR94032, ICSV700, ICSL71193, ICSR94030, ICSL71253, ICSL71268, ICSL71023, ICSL71061 and ICSL71137 were resistant with selection index ranging from 0.0 to 0.5. These sorghum lines with various resistance to S. calamistis could be used as source of resistance and as parents in sorghum improvement programme in breeding for resistance to stem borer. Keywords: Genotypes, novel source of resistance, Sesamia calamistis , Sorghum bicolor DOI: 10.7176/JBAH/11-18-04 Publication date: September 30 th 2021

계단 형상의 단차가 적용된 팬 형상 막냉각 홀 하류에서의 막냉각 효율에 관한 실험적 연구

In this study, the adiabatic film cooling effectiveness downstream of a row of the fan-shaped film cooling holes with various staircase geometries at hole exit was measured and analyzed using a pressure sensitive paint method. Experiments were conducted with baseline fan-shaped film cooling hole and the three different configurations with staircase geometry, in which ‘two-step’ geometry was applied to the hole exit and its lateral length is changed from 2.3D to 6D. A low-speed open-type wind tunnel was used for the experiments. The density ratio of the coolant fluid to main stream was 1.0 and the blowing ratio ranged between 0.5 and 2.0. The result showed that the staircase geometry promotes lateral spreading of the coolant at the hole exit, which results in better film coverage near the hole. At low blowing ratio, the film cooling effectiveness distributions are quite similar for all the tested cases except near the hole exit because the momentum of the coolant is low and baseline configuration also has good coverage downstream of the hole. However as the blowing ratio becomes higher, the effect of the staircase geometry becomes stronger and higher film cooling effectiveness values are obtained due to increased film coverage with reduced momentum of the coolant on the whole measured area.

Experimental Investigation of Hole Exit Damage in Stacked Drilling of Carbon Fiber Reinforced Composites

Experimental Investigation of Hole Exit Damage in Stacked Drilling of Carbon Fiber Reinforced Composites

A Study on Impact of Pellets on Different Targets- A Preliminary Study

Background: Forensic investigators often comes across cases where the projectile is found in severelydamaged condition, fragmented, or not recovered from the victim or the scene of crime. Analysis of entryand exit hole becomes essential to determine the calibre or type of projectile used to aid investigation.Purpose: The present study was performed to study impact made by lead and copper pellets fired fromHammerli AR 20 7.5 Joules where targets used were fabric (cotton and silk), glass (sodalime glass, texturedand privacy pane) and wood (MDF and plywood).Procedure: The current study was performed using fabric (cotton and silk), glass (sodalime glass, texturedand privacy pane) and wood (MDF and plywood) by firing pellets firing at10 metres.Main findings: The fibres protruded outwards around margin of entry hole. The diameter of entry hole, exithole and penetration depth was consistent among the same type of target.Conclusion: Post analysis of the present data was done to study the influence of lead and copper pelletson wood, cloth and glass on entry and exit holes. However, it was found that in both cases (i.e., entry andexit holes), the target groups have a significant difference but in case of pellets of same calibre, there is aninsignificant difference with entry and exit holes.

Dual-stage artificial neural network (ANN) model for sequential LBMM-μEDM-based micro-drilling

A sequential process combining laser beam micromachining (LBMM) and micro electro-discharge machining (μEDM) for the micro-drilling purpose was developed to incorporate both methods’ benefits. In this sequential process, a guiding hole is produced through LBMM first, followed by μEDM applied to that same hole for more fine machining. This process facilitates a more stable, efficient machining regime with faster processing (compared to pure μEDM) and a much better hole quality (compared to LBMMed holes). Studies suggest that strong correlations exist between the various input and output parameters of the sequential process. However, a mathematical model that maps and simultaneously predicts all these output parameters from the input parameters is yet to be developed. Our experimental study observed that the μEDM finishing operation’s various output parameters are influenced by the morphological condition of the LBMMed holes. Hence, an artificial neural network (ANN)-based dual-stage modeling method was developed to predict the sequential process’s outputs. The first stage of the dual-stage model was utilized to predict various LBMM process outputs from different laser input parameters. Furthermore, in the second stage, LBMM-predicted outputs (such as pilot hole entry area, exit area, recast layer, and heat-affected zone) were used for the final prediction of the sequential process outputs (i.e., machining time by μEDM, machining stability during μEDM in terms of short circuit/arcing count, and tool wear during μEDM). The model was evaluated based on the average RMSE (root mean square errors) values for the individual output parameters’ complete set data, i.e., μEDM time, short circuit/arcing count, and tool wear. The values of average RMSE for the parameters as mentioned earlier were found to be 0.1272 (87.28% accuracy), 0.1085 (89.15% accuracy), and 0.097 (90.3% accuracy), respectively.

Film cooling performance for the cratered film-cooling holes with various coolant crossflow orientations

The present study investigates the influence of the coolant crossflow orientation on the cooling performance for the cratered film-cooling hole. It is well known that the quiescent coolant plenum is mostly adopted in the laboratory for convenience. In the present article, the coolant crossflow channels with three possible orientations in practice are further considered. The flow fields for the film-cooling are solved with the RANS method with the SST turbulence model at blowing ratios of 0.5, 1.0, and 2.0. The numerical results show that the coolant crossflow orientation significantly alters the coolant flow at the hole exit, further the downstream vortex structure and the cooling effectiveness. The symmetric flow and cooling effectiveness distribution occur for the quiescent plenum case, in-line parallel crossflow case, and the counter parallel crossflow case provide, but the asymmetrical flow and cooling effectiveness distribution for the perpendicular crossflow. The in-line parallel crossflow case gives almost considerable cooling effectiveness as the common quiescent plenum case. On the other hand, the counter-parallel crossflow case provides the worst cooling performance due to the opposite flow direction of the coolant supply relative to the mainstream flow. At the high blowing ratio of 2.0, the cooling performance is higher for the perpendicular crossflow feeding despite its asymmetrical distribution of the cooling effectiveness.

Point angle effect in drilling of syntactic foams

Borosilicate glass microballoons (GMBs) of three different density grades are dispersed in epoxy resin for fabricating syntactic foams. The influence of different twist drill (coated solid tungsten carbide) point angles (85,110, and 135°) in dry drilling is conducted through full factorial design using a vertical machining centre. The influence of various parameters in drilling (point angle, feed, cutting speed) and GMBs density are examined, and their effects are reported. Analysis of variance and response surface methodology is employed to determine the significant parameters influencing the responses. Drill point angle shows a substantial impact on cylindricity (31.81%), circularity error (42.86%) and damage factor at hole exit (34.29%). Feed significantly affects the thrust force (40.76%) and specific cutting coefficient (53.60%), whereas surface roughness is highly influenced by GMBs density (47.05%). Cutting speed governs cylindricity (32.73%) and exit side damage factor (43.38%) of the drilled holes. Multiple response optimization based on grey relational analysis reveals that combining higher feed, lower cutting speed and drill point angle, and intermediate GMBs density is the optimal condition for achieving sound quality hole. Drill point angle has a remarkable impact (88.35%) on hole quality at the optimum condition. Chip morphology of syntactic foams is presented finally. This research may be beneficial for the industrial practitioners in minimizing poor hole quality, thereby saving time and cost in drilling syntactic foams used in weight-sensitive structures.

Drilling induced delamination assessment of nanoparticles reinforced polymer matrix composites

The knowledge of polymer matrix composites machinability has increased with its rise in multi-field structural applications. Drilling of polymer matrix composites is required to achieve structural integration with greater accuracies. Delamination due to drilling affects the material strength and it occurs at both the entry and hole exit planes. The delamination on the exit plane is critical. The effect of nano-fillers on drilling-induced delamination of reinforced plastics has not been documented extensively and in this article, an attempt is made to explore the application potential of montmorillonite clay and graphene with amine functionalization in minimizing delamination through toughening the epoxy matrix. Experimentation was based on Taguchi’s L16 approach. The delamination factor and circularity ratio were analyzed using an image processing technique in Matlab and Image J. To evaluate the effects of various parameters and parameters interaction effect on the delamination factor, ANOVA was employed and Signal/noise ratios were calculated. The mathematical models were developed for delamination. It was observed that the reduction in the delamination factor was observed in nanoclay and graphene reinforced polymer matrix toughened composites in comparison to the base composites with a reduction in thrust force, specific cutting energy, and increase in circularity ratio.

Heat-Affected Zone and Mechanical Analysis of GFRP Composites with Different Thicknesses in Drilling Processes.

This article presents a comprehensive thermomechanical analysis and failure assessment in the drilling of glass fiber-reinforced polymer (GFRP) composites with different thicknesses using a CNC machine and cemented carbide drill with a diameter of 6 mm and point angles of ϕ = 118°. The temperature distribution through drilling was measured using two techniques. The first technique was based on contactless measurements using an IR Fluke camera. The second was based on contact measurements using two thermocouples inserted inside the drill bit. A Kistler dynamometer was used to measure the cutting forces. The delamination factors at the hole exit and hole entry were quantified by using the image processing technique. Multi-variable regression analysis and surface plots were performed to illustrate the significant coefficients and contribution of the machining variables (i.e., feed, speed, and laminate thickness) on machinability parameters (i.e., the thrust force, torque, temperatures, and delamination). It is concluded that the cutting time, as a function of machining variables, has significant control over the induced temperature and, thus, the force, torque, and delamination factor in drilling GFRP composites. The maximum temperature recorded by the IR camera is lower than that of the instrumented drill because the IR camera cannot directly measure the tool–work interaction zone during the drilling process. At the same cutting condition, it is observed that by increasing the thickness of the specimen, the temperature increased. Increasing the thickness from 2.6 to 7.7 had a significant effect on the heat distribution of the HAZ. At a smaller thickness, increasing the cutting speed from 400 to 1600 rpm decreased the maximum thrust force by 15%. The push-out delaminations of the GFRP laminate were accompanied by edge chipping, spalling, and uncut fibers, which were higher than those of the peel-up delaminations.

Power-Optimizing Repair for Distal Biceps Tendon Rupture: Stronger and Safer

PurposeMany approaches have been described to accomplish tendon reattachment to the radial tuberosity in a distal biceps tendon rupture, with significant success, but each is associated with potential postoperative complications, including posterior interosseous nerve (PIN) injury. To date, there has been no consensus on the best approach to the repair. The purpose of this study was to evaluate the supination strength and the distance of drill exit points from the PIN in a power-optimizing distal biceps repair method and compare the findings with those of a traditional anterior approach endobutton repair method.MethodsCadaveric arms were dissected to allow for distal biceps tendon excision from its anatomic footprint. Each arm was repaired twice, first with the power-optimizing repair using an anterior single-incision approach with an ulnar drilling angle and biceps tendon radial tuberosity wraparound anatomic footprint attachment, then with the traditional anterior endobutton repair. Following each repair, the arm was mounted on a custom-built testing apparatus, and the supination torque was measured from 3 orientations. The PIN was then located posteriorly, and its distance from each repair exit hole was measured.ResultsFive cadaveric arms, each with both the repairs, were included in the study. On average, the power-optimizing repair generated an 82%, 22%, and 13% greater supination torque than the traditional anterior endobutton repair in 45° supination, neutral, and 45° pronation orientations, respectively. On average, the power-optimizing repair produced drill hole exit points farther from the PIN (23 mm) than the traditional anterior endobutton repair (14 mm).ConclusionsThe power-optimizing repair provides a significantly greater supination torque and produces a drill hole exit point significantly farther from the PIN than the traditional anterior endobutton approach.Type of study/level of evidenceTherapeutic III.

Effects of trench configuration on the film cooling effectiveness of a fan-shaped hole

In this study, the effects of three trench configurations – the height, the distance from the hole exit to the downstream sidewall, and the radius of the curvature of the downstream sidewall – on the film cooling effectiveness of fan-shaped holes were experimentally investigated. The film cooling effectiveness was measured using pressure sensitive paint (PSP), and the experiment was conducted with blowing ratios of 1.0, 1.5, 2.0, and 2.5, and density ratios of 1.0 and 2.0. The results demonstrated that the film cooling effectiveness inside the trench was generally higher for cases with larger trench heights, smaller distances between the hole exit and downstream sidewall, and smaller radii of curvature. The smaller distances between the hole exit and downstream sidewall showed higher film cooling effectiveness outside the trench. The higher density ratio cases resulted in higher overall film cooling effectiveness. In general, the film cooling effectiveness for fan-shaped holes with a trench was higher than that without a trench. However, a lower trench resulted in lower film cooling effectiveness.

Machining Temperature and Accuracy of Magnesium Alloy AZ31 with Deep-Hole Small Drilling

In recent years, magnesium-based materials have become expected to replace conventional engineering plastics as next-generation industrial materials to protect the global environment. However, in the production technology, problems of cracking and unstable accuracy in drilled hole shapes persist in plastic molding and machine tool processing; many studies have been conducted to address these problems. In dry machining ignition can be caused by the material, so wet machining is the prevalent method. However, it is necessary to establish a machining method with improved environmental parameters, considering the impact of oil mist and waste oil treatment on woks. In this study, the relationship between machining temperature and the accuracy of hole shapes in magnesium alloy AZ31 is investigated with four types of drills: high-speed steel, cemented carbide (K-Base), diamond-like carbon (DLC; K-Base), and TiN-coated cemented carbide (K-Base). The drill tip angle is set to 116°, 118°, or 120°. The work material used is the extruded AZ31 magnesium alloy. To evaluate the hole shape accuracy, squares of 80 × 80 mm are used. The cutting temperature is measured over an area of 12 × 30 mm. The work material is drilled using a dry method with a 3-mm-diameter drill having the aspect ratio (L/D) of 10. The tool protrusion length of 50 mm and cutting speed of 20 m/min are fixed, and the tool feed rate and drill step amount are changed. The experiment is repeated 3 times. The burr generated around the loophole on the back surface of the test material after the test is evaluated with a criterion burr height H of 0.02 mm. Furthermore, the average roughness (Ra) of the centerline is measured on the inner surface of the hole with a contact-type roughness meter. The results show that when using the three drill point angles of 116°, 118°, and 120° in the drill step, no burrs form at the exit of the drill hole. Carbide tools form burrs when the feed rate exceeds 30 mm/min and the step amount exceeds 20 mm. TiN tools are highly accurate up to a tip angle of 118°, while DLC tools have lower cutting forces and yield better finished surfaces than the other tools.

Mechanisms of transport enhancement for self-propelled nanoswimmers in a porous matrix

Micro/nanoswimmers convert diverse energy sources into directional movement, demonstrating significant promise for biomedical and environmental applications, many of which involve complex, tortuous, or crowded environments. Here, we investigated the transport behavior of self-propelled catalytic Janus particles in a complex interconnected porous void space, where the rate-determining step involves the escape from a cavity and translocation through holes to adjacent cavities. Surprisingly, self-propelled nanoswimmers escaped from cavities more than 20× faster than passive (Brownian) particles, despite the fact that the mobility of nanoswimmers was less than 2× greater than that of passive particles in unconfined bulk liquid. Combining experimental measurements, Monte Carlo simulations, and theoretical calculations, we found that the escape of nanoswimmers was enhanced by nuanced secondary effects of self-propulsion which were amplified in confined environments. In particular, active escape was facilitated by anomalously rapid confined short-time mobility, highly efficient surface-mediated searching for holes, and the effective abolition of entropic and/or electrostatic barriers at the exit hole regions by propulsion forces. The latter mechanism converted the escape process from barrier-limited to search-limited. These findings provide general and important insights into micro/nanoswimmer mobility in complex environments.

Simulation of transient effects in a fuel injector nozzle using real-fluid thermodynamic closure

Numerical predictions of the fuel heating and cavitation erosion location indicators occurring during the opening and closing periods of the needle valve inside a five-hole common rail Diesel fuel injector are presented. These have been obtained using an explicit density-based solver of the compressible Navier-Stokes (NS) and energy conservation equations; the flow solver is combined with two thermodynamic closure models for the liquid, vapour and vapour-liquid equilibrium (VLE) property variation as function of pressure and temperature. The first is based on tabulated data for a 4-component Diesel fuel surrogate, derived from the Perturbed-Chain, Statistical Associating Fluid Theory (PC-SAFT) Equation of State (EoS), allowing for the variation of the physical and transport properties of the fuel with the local pressure and temperature to be quantified. The second thermodynamic closure is based on the widely used barotropic Equation of State (EoS) approximation between density and pressure only and neglects viscous heating. The Wall Adapting Local Eddy viscosity (WALE) LES model was used to resolve sub-grid scale turbulence while a cell-based mesh deformation Arbitrary Lagrangian–Eulerian (ALE) formulation is used for modelling the injector's needle valve movement. Model predictions are found in close agreement against 0-D estimates of the temporal variation of the fuel temperature difference between the feed and hole exit during the injection period. Two mechanisms affecting the temperature distribution within the fuel injector have been revealed and quantified. The first is ought to wall friction-induced heating, which may result to local liquid temperature increase up to fuel's boiling point while superheated vapour is formed. At the same time, liquid expansion due to the depressurisation of the injected fuel results to liquid cooling relative to the fuel's feed temperature; this is occurring at the central part of the injection orifice. The spatial and temporal temperature and pressure gradients induce significant variations in the fuel density and viscosity, which in turn, affect the formed coherent vortical flow structures. It is found, in particular, that these affect the locations of cavitation formation and collapse, that may lead to erosion of the surfaces of the needle valve, sac volume and injection holes. Model predictions are compared against corresponding X-ray surface erosion images obtained from injector durability tests, showing good agreement.

Adiabatic effectiveness and heat transfer measurements of simple and trenched cylindrical holes with backward injection

Recent studies have demonstrated that the simple cylindrical hole with backward injection, where the jets are injected reverse to the mainstream flow direction, outperforms its forward-injected counterpart at relative high blowing ratios. Meanwhile, trench is known to be of high cooling effectiveness with forward injection at high blowing ratios. Few studies addressed the combination of the two setups. The present study investigated the simple and trenched cylindrical hole configurations with either forward or backward injection by experiments. The injection angle was 30° and 150° for the forward and backward setup separately. The trench had a depth of 0.75D and the trench width was 1D and 2D. Adiabatic effectiveness was measured with PSP, and heat transfer augmentation was obtained with transient method using the IR camera. Detailed distributions were obtained. Blowing ratio was varied from 0.25 to 4.0. The density ratio was 1.0 or 1.5 in PSP measurements, and was 1.0 only for the heat transfer measurements. For the simple cylindrical hole with backward injection, the result confirmed the advantage of it at high blowing ratios, and also showed that its adiabatic effectiveness is highly uniform in the spanwise direction. Meanwhile, the backward-injected configuration had a much more stable cooling performance as the VR varied. It was further pointed out that the flow field of the simple backward-injected case is governed by the recirculated region downstream the hole exit. The narrow trench enhanced the effectiveness hugely along with forward injection, while the enhancement to the simple backward injection was quite limited. Moreover, the narrow trench performed far better than the wide trench. It was revealed that the key of the mechanism depends on the interaction of the jet with the downstream trench wall.

Effect of Mainstream Velocity on the Optimization of a Fan-Shaped Film-Cooling Hole on a Flat Plate

In this study, the effect of mainstream velocity on the optimization of a fan-shaped hole on a flat plate was experimentally investigated. The experiment was conducted by changing the forward expansion angle (βfwd), lateral expansion angle (βlat), and metering length ratio (Lm/D) of the film-cooling hole. A total of 13 cases extracted using the Box–Behnken method were considered to examine the effect of the shape parameters of the film-cooling hole under a 90 m/s mainstream velocity condition, and the results were compared with the results derived under a mainstream velocity of 20 m/s. One density ratio (DR = 2.0) and a blowing ratio (M) ranging from 1.0 to 2.5 were considered, and the pressure-sensitive paint (PSP) technique was applied for the film-cooling effectiveness (FCE). As a result of the experiment, the optimized hole showed a 49.3% improvement in the overall averaged FCE compared to the reference hole with DR = 2.0 and M = 2.0. As the blowing ratio increased, the hole exit area tended to increase, and this tendency was the same as that in the 20 m/s mainstream condition.

Investigation of effect of abrasive water jet (AWJ) machining parameters on aramid fiber-reinforced polymer (AFRP) composite materials

PurposeThe purpose of this study was to optimize the surface roughness (Ra), delamination damage at the hole entrance (FdT) and at the hole exit (FdB) and kerf angle (K) in the drilling of aramid fiber-reinforced polymer (AFRP) composite material using abrasive water jet (AWJ) machining.Design/methodology/approachThe AFRP composite was produced by the vacuum infusion method. The drilling experiments were performed on an AWJ machine using a three-axis computerized numerical control system. Machine processing parameters were determined as water pressure (2,000, 3,000 and 4,000 bar), stand-off distance (2, 4 and 6 mm) and traverse feed rate (150, 250 and 350 mm/min). Optimization of processing parameters in the drilling experiments was carried out according to the Taguchi L27 (33) orthogonal array. In addition, gray relational analysis (GRA) was used to analyze the complex uncertainty affecting the results.FindingsResults of the drilling operations demonstrated that water pressure (P) was the most effective parameter, with 65.3%, 65.2%, 49.8% and 52.1% contribution rates for Ra, FdT, FdB and K, respectively.Practical implicationsReliable results have been obtained with Taguchi-based GRA while drilling AFRP composite material using AWJ. Significant results have been achieved to increase the hole quality in the drilling of AFRP composite material.Originality/valueThe new approach is to present more detailed analysis by using Taguchi method and multi-decision Taguchi-based gray relation analysis in AFRP composite material drilling using AWJ. Thus, time and experiment costs are saved.