Pilot Hole Research Articles

Thermal optimization of robotic piezoelectric osteotomy motion in porcine trabecular bone

BackgroundPiezoelectric osteotomy represents a potentially viable alternative to conventional techniques for preparing pilot holes for bone screws. However, piezoelectric osteotomes have demonstrated the potential to heat bone beyond 47 °C, which induces necrosis that could contribute to screw loosening, resulting in osteosynthetic material failure and pseudarthrosis. Thus, we sought to determine the working movements of a piezoelectric drill that resulted in the lowest maximum bone temperatures while ensuring that this optimal drilling motion resulted in temperatures below 47 °C. MethodsVertebrae samples were obtained fresh from a local abattoir. A robot was used to drill 15 mm holes through the vertebrae bodies parallel to a sectioned viewing surface, observed with a thermal camera. We tested three significant aspects of the osteotome's movement: the feed rate, retraction speed and working cycle to see which combination resulted in the lowest maximum temperatures. Each factor combination was tested three times for a total of 24 trials. FindingsA feed rate of 2 mm/s, a retraction speed of 2 mm/s and a novel working cycle termed “multi-pass” were found to generate the lowest maximum temperatures (41.5 °C, σ = 1.91 °C). The factors of retraction speed and working cycle demonstrated statistical significance through analysis of variance, with ordinary least squares regression indicating their optimal settings resulted in reductions in maximum temperatures of 4.95 °C and 5.63 °C, respectively. InterpretationRobotic piezoelectric osteotomy appears to represent a safe method of pedicle screw pilot hole preparation from a thermal perspective when using the optimal methods found in this study.

A New Pilot Hole Preparation System for Percutaneous Pedicle Screw Placement - A Randomized Controlled Study.

Randomized controlled study. To introduce a new pilot hole preparation system for percutaneous pedicle screw placement and investigate its efficiency and safety in comparison with the conventional method. Placing screws accurately, rapidly, and safely with less radiation exposure is critical for minimally invasive Lumbar interbody fusion (LIF). Optimizing pilot hole preparation instruments has important clinical implications. A total of 60 patients (180 screws) were included in this study. All patients were randomized into two groups (new system vs conventional method) and performed single-level minimally invasive percutaneous fixation, interbody fusion, and unilateral decompression. Basic information, time of pilot hole preparation, time of screw placement, and fluoroscopy time were recorded. Screw placement accuracy was graded based on the Gertzbein-Robbins scale, and the angle between the screw axis and the pedicle axis was collected in postoperative CT. There was no statistical difference in basic information between the two groups. The mean time of single pilot hole preparation was 4.08±1.01 min in the new system group and 5.34±1.30 min in the conventional method group (P<0.001). The time of single screw placement was significantly shorter in the new system group (0.82±0.20 vs 1.72±0.33min), and the fluoroscopy time was also less in the new system group (13.70±3.42 vs 19.95±5.50 s) (P<0.001). Screw placement accuracy assessment showed that there were 85 (94.45%) A-grade screws in the new system group while 76 (84.44%) A-grade screws in the conventional method group (P=0.027). The new pilot hole preparation system has shown significant reductions in the time of pilot hole preparation, time of screw placement, and radiation exposure, and has good clinical application value.

Individualized Design Application of 3-Dimensional Printing Navigational Template for Pedicle Screw Installation: A Training Case Report.

BACKGROUND The proper installation for pedicle screws by the traditional method of surgeons dependent on experience is not guaranteed, and educational solutions have progressed from chalkboards to electronic teaching platforms. We designed a case of 3-dimensional printing drill guide template as a surgical application, which can accurately navigate implantation of pedicle screws, and assessed its effect for simulative training. MATERIAL AND METHODS We randomly selected a set of computed tomography data for spondylolisthesis. A navigational template of pedicles and screws was designed by software Mimics and Pro-E, where trajectories of directions and angles guiding the nail way were manipulated for screwing based on anatomy, and its solid model was fabricated by a BT600 3D printer. The screws were integrated and installed to observe their stability. RESULTS The navigational model and custom spine implants were examined to be compatibly immobilized, because they are tolerant to radiation and stable against hydrolysis. The screw size and template were fit accurately to the vertebrae intraosseously, because the pilot holes were drilled and the trajectories were guided by cannulas with visible routes. During the surgical workflow, the patient reported appreciation and showed substantial compliance, while having few complications with this approach. Compared with fluoroscopy-assisted or free-hand techniques, the effect of simulative training during processing was excellent. CONCLUSIONS The surgical biomodel is practical for the procedural accuracy of surgical guides or as an educational drill. This fostering a style of "practice substituting for teaching" sets a paragon of keeping up with time and is worthy of recommendation.

Influence of Pilot Hole and Work Material Hardness on Thread Milling with a Wireless Holder System

Influence of Pilot Hole and Work Material Hardness on Thread Milling with a Wireless Holder System

HF/HR VSP acquisition, processing, and interpretation in the deviated section of the high angle geothermal borehole of Grigny GGR5, targeting intra Dogger thin, porous beds.

Defining 5m thin, or even thinner, porous reservoir beds was the feasibility objective assigned to the High Frequency/High Resolution (HF/HR) look ahead VSP survey to be recorded in the deviated section of a geothermal production well drilled down to the top of the carbonate Dogger aquifer in the Paris basin, around 1500m in vertical depth, with a landing angle of 65°. The idea was to predict the depth of the first porous bed(s) to be drilled at high angle, and to determine the minimal DLS (Dog Leg Severity) to be applied by the driller after setting a production casing at the top Dogger level and changing the drilling fluid composition, so as to avoid directional drilling with sharp angles. A 50-100m vertical depth range was targeted for the acoustic impedance to be predicted below the top Dogger carbonate aquifer. Besides, a Pilot Hole (PH) was drilled prior to the high angle leg to assess with full reliability the depth of productive thin beds to be subsequently drilled at high angle. These actions were undertaken within a global R&amp;D project named “SISMOSUB” aiming reservoir characterisation, conducted by the reservoir and drilling engineers of GEOFLUID/GPCIP, in a partnership with IFPEN, and partially financed by ADEME (French Agency for Ecological Transition). High Frequency (HF) VSP still represents a frontier seismic domain to investigate, for which technical difficulties are piling up: First, the surface fix source needs to be extremely repeatable and preferably deliver an increased amount of HF energy to compensate somehow for the higher loss of seismic amplitudes with high frequency. Second, downhole receiver tool or toolstring may not present constant vector fidelity of 3 component reception over the whole recording frequency range, mainly in high frequency, due to mechanical coupling characteristics of the VSP tool hardware and the open borehole ruggedness; in cased hole, the mechanical coupling of the VSP tool to the formation is insured by a good cementing quality between casing and borehole wall. Third, the physics of the seismic attenuation is not fully understood and depends on several factors, mainly viscoelasticity and heterogeneity, potentially variable in depth and laterally to the wellbore. Additionally, the geometrical spreading represents the main factor of amplitude decay, independent from frequency, and can be estimated at processing stage. Surprisingly, the VSP image produced underneath the deviated hole section evidenced a faulted structure. A remarkable abrupt amplitude loss of high frequencies above 120Hz occurs where the direct P-wave ray crosses one of the confirmed minor faults before reaching Total Depth (TD); secondary downgoing arrivals appear locally in depth, mainly in the high frequencies, which are not strictly parallel to the first P-wave arrival...

Copper foil microforming through underwater laser oblique impact

Laser-induced cavitation impact forming is a high-speed forming process that employs a high-energy laser to produce cavitation in a liquid and act on the workpiece. When the laser is irradiated vertically to the workpiece surface through the guide hole, oxidation occurs on the produced workpiece's surface, affecting the surface quality. Laser-induced cavitation oblique impact workpiece formation is proposed in this paper. The surface quality of the workpiece created at various angles is investigated by adjusting the angle between the laser and the guide hole. A finite element model (FEM) was employed to simulate the temperature change and collapse speed of laser-induced cavitation, and a hydrophone was utilized to measure the impact pressure of laser-induced cavitation under various guide holes. The variations in forming depth and surface quality of the workpiece caused by laser-induced cavitation oblique impact were investigated experimentally. The experimental results show that as the angle between the laser and the guide hole increases from 0° to 90°, the width of the oxidized area on the surface of the formed micro-groove decreases from 513 μm to 0 μm, the forming depth of the micro-groove decreases from 80 μm to 20 μm, and the surface roughness of formed parts decreases from 2.93 μm to 0.56 μm. The oxidation of the formed workpiece surface during the oblique laser impact is primarily caused by the laser irradiation, according to the analysis of the surface oxidation mechanism of the formed micro-grooves. When the angle between the laser and the guide hole is 60°, all of the heat emitted by the laser is focused to the guide hole's inner surface. The angle between the laser and the pilot hole was set to 60° in the experiment, and the micro-groove structure was generated by three impacts, with the thickness distribution of the formed groove investigated. The results demonstrate that the largest thinning of the micro-groove cross-section occurs at the mold's entry and the bottom of the micro-groove, with thinning rates of 20 % and 15 %, respectively.

Assessment of Thermal Osteonecrosis during Bone Drilling Using a Three-Dimensional Finite Element Model.

Bone drilling is a common procedure used to create pilot holes for inserting screws to secure implants for fracture fixation. However, this process can increase bone temperature and the excessive heat can lead to cell death and thermal osteonecrosis, potentially causing early fixation failure or complications. We applied a three-dimensional dynamic elastoplastic finite element model to evaluate the propagation and distribution of heat during bone drilling and assess the thermally affected zone (TAZ) that may lead to thermal necrosis. This model investigates the parameters influencing bone temperature during bone drilling, including drill diameter, rotational speed, feed force, and predrilled hole. The results indicate that our FE model is sufficiently accurate in predicting the temperature rise effect during bone drilling. The maximum temperature decreases exponentially with radial distance. When the feed forces are 40 and 60 N, the maximum temperature does not exceed 45 °C. However, with feed forces of 10 and 20 N, both the maximum temperatures exceed 45 °C within a radial distance of 0.2 mm, indicating a high-risk zone for potential thermal osteonecrosis. With the two-stage drilling procedure, where a 2.5 mm pilot hole is predrilled, the maximum temperature can be reduced by 14 °C. This suggests that higher feed force and rotational speed and/or using a two-stage drilling process could mitigate bone temperature elevation and reduce the risk of thermal osteonecrosis during bone drilling.

Влияние мелкозалегающего газа на проектные решения по освоению морских газоконденсатных месторождений на шельфе арк­тических и суб­арк­тических морей

The article discusses issues related to shallow gas influence on design decisions for the development of offshore oil and gas condensate fields. The authors show the presence and distribution of shallow gas accumulations in the upper part of the geological section and its influence on the quality of seismic surveys. The release of shallow gas has caused many serious accidents at offshore drilling rigs and oil and gas production platforms. The main danger of shallow gas deposits is when drilling intervals for the conductor and surface casing due to the lack of blowout equipment at the wellhead. The authors analyze the areal and depth distribution of shallow gas in the Arctic and subarctic seas, and find out that small deposits of several hundred meters in size are most common. The main methods of detecting and studying shallow gas accumulations above gas-bearing structures are high-resolution seismic exploration, drilling of engineering-geological wells and pilot holes with well logging. The researchers reveal the main features of the wave pattern indicating the gas saturation in the upper part of the section. They present the main technical solutions for the development of the Lunsky, Kirinsky and Yuzhno-Kirinsky oil and gas condensate fields located on the self of Sakhalin Island and suggest changes in design solutions during their development in view of the shallow gas presence in the upper part of the geological section. The authors substantiate the need to create Russian software systems and methods of automated design for developing offshore oil and gas fields in the Arctic, taking into account geological and geophysical uncertainty, the shallow gas presence and technical factors.

Investigation of Effective Fracture Height Using Strain Responses in a Vertical Monitoring Well during a Well Interference Test

Summary Understanding and characterizing the effective hydraulic fracture height are critical for optimizing completion design and well performance in unconventional reservoirs. Rayleigh frequency shift distributed strain sensing (RFS-DSS) data provide crucial information about the fracture geometry by measuring the strain change along the fiber. Recently, the strain data from the vertical monitoring well [VMW; Boxwood 5 Pilot Hole (B5PH)] at Hydraulic Fracture Test Site 2 (HFTS-2) was collected during a well interference test conducted on two neighboring horizontal wells [Boxwood 3H (B3H) and Boxwood 4H (B4H)] in September 2020. However, this data set was overlooked and not comprehensively analyzed. Consequently, the valuable information that this data may provide remains unexplored. The objective of this study is to determine how to interpret this vertical strain data and assess its potential to provide insights into the effective fracture height generated in the horizontal wells. To understand the measured strain data, we have developed a coupled fluid flow and geomechanics model to simulate the vertical strain responses observed during production and the well interference test. The characteristics of the strain responses are thoroughly analyzed to establish guidelines for identifying the upper and lower tips of the effective fracture in different fracture geometry scenarios. In addition, field-measured data are examined, and a history-matching process is conducted by comparing the numerical matching results with the observed data to identify the effective fracture height. Furthermore, the pressure gauge data are analyzed and compared with the strain data results to further validate the findings. The study has demonstrated that vertical strain measurements obtained from a VMW can be used to determine the effective fracture height. Large strain responses, characterized by both negative and positive peaks, are observed near the tips of the effective fractures. The upper and lower tips of the effective fracture can be identified by examining the locations of zero-strain change. The magnitude of strain response is affected by the distance between the fracture and the fiber. It is worth noting that the locations where the absolute value of the derivative of fracture conductivity changes abruptly correspond to the positions of the fracture tips. Furthermore, we study and history match the field-measured vertical strain change in HFTS-2 data sets. The pressure gauge data are analyzed to further validate our findings. The effective fracture height determined from the strain measurements falls within the range of 11,360–11,616 ft, which is consistent with the values obtained from pressure gauges (11,360–11,635 ft). Specifically, for B4H, the effective fracture height was determined to be 256 ft at a distance of 330 ft away at the time of data acquisition. Overall, the strain measurements provide valuable, time-dependent insights into the effective fracture height and the active drainage interval.

Research on trajectory control technology for L-shaped horizontal exploration wells in coalbed methane

Horizontal wells have significant advantages in coal bed methane exploration and development blocks. However, its application in new exploration and development blocks could be challenging. Limited geological data, uncertain geological conditions, and the emergence of micro-faults in pre-drilled target coal seams make it hard to accurately control the well trajectory. The well trajectory prior to drilling needs to be optimized to ensure that the drilling trajectory is within the target coal seam and to prevent any reduction in drilling ratio (defined here as the percentage of the drilling trajectory in the entire horizontal section of the well located in the target coal seam) caused by faults. In this study, the well trajectory optimization is achieved by implementing the following process to drill pilot hole, acquire 2D resonance, and azimuthal gamma logging while drilling. The pilot hole drilling can obtain the characteristic parameters of the target coal seam and the top and bottom rock layers in advance, which can provide judgment values for the landing site design and real-time monitoring of whether the wellbore trajectory extends along the target coal seam; 2D resonance exploration can obtain the construction of set orientation before drilling and the development of small faults and formation fluctuations in the horizontal section, which can optimize the well trajectory in advance; the azimuth gamma logging while drilling technology can monitor the layers drilled by the current drill bit in real time, and can provide timely and accurate well trajectory adjustment methods.The horizontal well-Q in the Block-W of the Qinshui Basin was taken as a case study and underwent technical mechanism research and applicability analysis. The implementation of this new innovative process resulted in a successful drilling of a 711 m horizontal section, with a target coal seam drilling rate of 80%. Compared to previous L-type wells, the drilling rate increased by about 20%, and the drilling cycle shortened by 25%. The technical experience gained from this successful case provides valuable insight for low-cost exploration and development of new coalbed methane blocks.

Accurate placement of thoracolumbar pedicle screws using a handheld iOS-based navigation device: a prospective intra-patient agreement study

BACKGROUNDAccurate pedicle screw placement is a challenge with reported misplacement rates of 10% and higher. A handheld navigation device (HND) may provide accuracy equal to CT-based navigation (CT-Nav) but without the cost and complexity. OBJECTIVETo study the accuracy of a handheld navigation device for pedicle screw placement. STUDY DESIGNThis prospective cross-sectional study with consistently applied reference standard enrolled 20 patients undergoing 92 pedicle screw placements. PATIENTSPatients who underwent pedicle screw placement between May 2022 and September 2022. OUTCOME MEASURESPedicle screw placement accuracy per Gertzbein–Robbins. METHODSOnce the screw pilot hole was established, the proposed trajectory of the HND was compared with that proposed by CT-Nav. Postoperatively, screw accuracy was graded according to Gertzbein–Robbins by a blinded radiologist based on CT scans. Accuracy was compared between the two systems and published control for fluoroscopy assisted and CT-Nav placement using Bayesian posterior distribution. RESULTSThe trajectory proposed by the HND and CT-Nav were in agreement in 98.9% (95% Exact CI; 94.09%–99.97%). The HND accuracy was 98.9% with 91 screws rated “A” and 1 rated “C”. Noninferiority to fluoroscopic placement was achieved because the one-sided normal-approximation 95% CI Lower Bound (LB) of 95.3% is greater than the Performance Goal (PG) of 83.4%. Posthoc analysis demonstrated that the probability of superiority of the HND relative to the historical accuracy rate of 91.5% for fluoroscopy assisted procedures is >0.999 and that the HND's accuracy rate is within 4.5% of CT-Nav of 95.5% is >0.999. No adverse events or intra-operative complications associated with HND were observed. There was 1 (1.1%) intra-operative repositioning and no reoperations for any reason. CONCLUSIONSThe accuracy rate of the HND was 98.9%, and the proposed trajectory matched with CT-Nav in 98.9% of the time. This is superior to the historical published accuracy rate for fluoroscopy-assisted procedures and equivalent to the historical published accuracy rate for CT-Nav. Clinical Trial Registration NumberDutch trial register NL74268.058.20.

Research on Rapid Construction Technology of Deep Water Rock-socketed Bridge Foundation

The construction of deep water rock-socketed bridge foundation is pretty difficult and people routinely use the method of combining underwater blasting and double-wall steel box cofferdam support for construction. Combined with the site construction conditions and analysis of FEM software, through schemes comparison and technical research, the paper puts forward the construction scheme of rotary drilling pilot hole, high-pressure rotary jet grouting pile for grouting and water stopping, and cofferdam support for locking steel pipe pile, which completes the foundation construction smoothly and rapidly. By adopting the technology, the construction period is greatly shortened, the material utilization rate is improved, the construction cost is reduced, and the scheme has reference significance for foundation construction under similar environments.

Influence of various pilot hole profiles on pedicle screw fixation strength in minimally invasive and traditional spinal surgery: a comparative biomechanical study.

Despite advancements in pedicle screw design and surgical techniques, the standard steps for inserting pedicle screws still need to follow a set of fixed procedures. The first step, known as establishing a pilot hole, also referred to as a pre-drilled hole, is crucial for ensuring screw insertion accuracy. In different surgical approaches, such as minimally invasive or traditional surgery, the method of creating pilot holes varies, resulting in different pilot hole profiles, including variations in size and shape. The aim of this study is to evaluate the biomechanical properties of different pilot hole profiles corresponding to various surgical approaches. Commercially available synthetic L4 vertebrae with a density of 0.16g/cc were utilized as substitutes for human bone. Four different pilot hole profiles were created using a 3.0mm cylindrical bone biopsy needle, 3.6mm cylindrical drill, 3.2-5.0mm conical drill, and 3.2-5.0mm conical curette for simulating various minimally invasive and traditional spinal surgeries. Two frequently employed screw shapes, namely, cylindrical and conical, were selected. Following specimen preparation, screw pullout tests were performed using a material test machine, and statistical analysis was applied to compare the mean maximal pullout strength of each configuration. Conical and cylindrical screws in these four pilot hole configurations showed similar trends, with the mean maximal pullout strength ranking from high to low as follows: 3.0mm cylindrical biopsy needle, 3.6mm cylindrical drill bit, 3.2-5.0mm conical curette, and 3.2-5.0mm conical drill bit. Conical screws generally exhibited a greater mean maximal pullout strength than cylindrical screws in three of the four different pilot hole configurations. In the groups with conical pilot holes, created with a 3.2-5.0mm drill bit and 3.2-5.0mm curette, both conical screws exhibited a greater mean maximal pullout strength than did cylindrical screws. The strength of this study lies in its comprehensive comparison of the impact of various pilot hole profiles commonly used in clinical procedures on screw fixation stability, a topic rarely reported in the literature. Our results demonstrated that pilot holes created for minimally invasive surgery using image-guided techniques exhibit superior pullout strength compared to those utilized in traditional surgery. Therefore, we recommend prioritizing minimally invasive surgery when screw implantation is anticipated to be difficult or there is a specific need for stronger screw fixation. When opting for traditional surgery, image-guided methods may help establish smaller pilot holes and increase screw fixation strength.

Anchorless Transosseous Rotator Cuff Repair: A Technical Note

Background: Transosseous rotator cuff repair provides robust fixation and broad footprint compression without the risk of foreign body reaction that may be seen with suture anchors. We present our technique for anchorless transosseous repair using a modern device to efficiently create bone tunnels and assist in suture passage. Indications: Tears of the supraspinatus tendon, with or without extension to the infraspinatus, in patients with acute or chronic tears, with good bone quality, and who fail appropriate nonoperative management. Technique: The beach-chair position with an articulating arm holder is preferred for this procedure. A glenohumeral diagnostic arthroscopy is performed, and intra-articular pathology is addressed as needed. The arthroscope is brought into the subacromial space, and a lateral viewing portal is established. A thorough bursectomy with or without acromioplasty is performed to attain visualization of the cuff. After the tear is identified, the tendon edges are debrided. It is critical to determine the tear pattern, the reduction maneuvers necessary, and the number of bone tunnels that are warranted. The desired location of the bone tunnel is marked with a pilot hole. The device is positioned over the pilot hole and a power drill is advanced through the lateral cortex. The device assists in creating a bone tunnel through the greater tuberosity and passes a nitinol loop through the tunnel. The loop is retrieved by the device and is brought to the lateral portal. Sutures are loaded into the loop and are brought through the bone tunnel. The sutures are then passed through the tendon using a curved retrograde suture passer in simple fashion and are tied to secure the tendon to the footprint. For larger tears, 2 or 3 tunnels may be used to widen the area for footprint compression. The specific configuration used will depend on the tear size, pattern, and surgeon preference. Results: Arthroscopic transosseous repairs have yielded promising results. Healing rates are comparable to anchor-based techniques, with the benefit of avoiding foreign bodies at the footprint. Discussion: Anchorless transosseous rotator cuff repair may be reproducibly performed with the use of a modern device for bone tunnel creation and suture passage. However, this technique should be used with caution in patients with osteoporosis or poor bone quality due to theoretical concerns of greater tuberosity fracture or suture pullout through the tunnels. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Novel 3D Printing Designs of Drywall Anchor

In this research project, the unique designs for 3D printed drywall anchors in this study were inspired by the skin of animals seen in nature, including reptiles, fish, and butterflies. The tough skin of these animals inspired our drywall anchor design. Engineered nylon produces drywall Anchors, one-piece, self-drilling drywall, and hollow cavity anchors. It may be installed in walls as thin as 12mm and optimized for drywall usage. You can screw with the nylon piece. A drywall sleeve anchor is an insert or sleeve made of plastic inserted into a tiny pilot hole. The sleeve enlarges as the drywall metal screw provided is threaded into it. This increases the shear strength, which helps the metal screw remain in the wall. Drywall sleeve anchors are often the sort of drywall anchor that has the lowest price point. They work well for lightweight products. The purpose of a drywall anchor is to firmly mount framed artwork, mirrors, clocks, and shelving to walls.

Influence of pilot hole on cutting force during threading with wireless holder system

Influence of pilot hole on cutting force during threading with wireless holder system

Optimization of Pedicle Screw Parameters for Enhancing Implant Stability Based on Finite Element Analysis

ObjectiveTo improve the implant stability, the parameters including outer diameter, thread depth and pitch of pedicle screw were optimized by finite element analysis. MethodsThe insertion and pullout of pedicle screw were simulated by finite element analysis, and the precision of simulation was evaluated by comparing with mechanical tests. The influences of the parameters on the maximum insertion torque and maximum pullout force were analyzed by computational simulations including single-factor analysis and orthogonal experiment. ResultsThe simulation results agree with the mechanical tests. The influencing orders of the parameters on insertion torque and pullout force are both: outer diameter > pitch > thread depth. When the pilot hole diameter is 0.1 mm larger than the inner diameter of pedicle screw, the calculated Pearson correlation coefficient between the maximum insertion torque and maximum pullout force is r = 0.99. The optimized pedicle screw shows a maximum insertion torque of 485.16 N·mm and a maximum pullout force of 1726.33 N, which are 23.9% and 9.1% higher than those of standard screw, respectively. ConclusionsThe presently used models are feasible to evaluate the implant stability of pedicle screw. The maximum insertion torque and maximum pullout force of pedicle screw are highly correlated. The insertion torque and pullout force can be improved by increasing outer diameter and decreasing pitch. Beside the parameters of pedicle screw, the size of pedicle and bone mineral density are two considerable factors for a better implant stability.

Curtain Grouting Test On Volcanic Breccia Foundation As An Effort To Assess The Effectiveness Of Grouting Case Study: Construction Of Minting Dam

Meninting Dam is located on the Meninting River, Meninting Watershed WS Lombok. Administratively, the location of this dam is located in Bukit Tinggi Village, Gunungsari District, and Gegerung Village, Lingsar District, West Lombok Regency. It is planned that Meninting Dam has a height of 79 m, the type of Urugan Zonal Random Dam with Upright Core, with a maximum storage capacity of 12.18 million m3 and an average storage capacity of 9.91 million m3. From the results of geological investigations during planning and pre-construction geological investigations, it is known that the body of the Meninting Dam will rest on a foundation in the form of volcanic breccia rock. Given that Meninting Dam has a reasonably high height, the foundation rock's quality is essential in terms of foundation permeability and the ability of the foundation rock to support the dam above it. On the left backrest, there is a volcanic breccia layer with a lousy level of cementation, which affects the high permeability value of the layer. In order to reduce the permeability value, it is necessary to conduct curtain grouting experiments to determine the extent of grouting effectiveness to reduce the permeability value and improve the overall foundation. The results of curtain grouting experiments and cement injection showed that the average incoming cement per meter was 21.43 kg / m or classified as efficient with a mixture change of 1 4. The effectiveness of grouting in poorly cemented volcanic breccia in Check Hole (CH) against Pilot Hole (G1) with an average of = 65% or classified as GOOD (Good) and seen semi-logarithmetically the significant decline of Lugeon towards target &lt; 3 according to technical specifications.

Effect of Epoxy Resin Reinforcement on Screw Withdrawal Strength of Fiberboard and Particleboard Used in Furniture Industry

The study aimed to increase the screw withdrawal strength of medium density fiberboard and particleboard used in furniture strength by using epoxy resin in the screw pilot hole. Therefore, the effects of pilot hole diameters, screw diameter, and amount of epoxy resin on screw withdrawal strength of medium density fiberboard and particleboard from face and edge were investigated. According to TS EN 13446, 50 mm &amp;times; 50 mm specimens were cut from commercial medium density fiberboard and particleboard boards. A static load was applied parallel to the screw direction. The screw withdrawal strength of medium density fiberboard was higher than the screw withdrawal strength of particleboard because of its density. Besides, the screw withdrawal strength of medium density fiberboard and particleboard samples with a 3.5 mm screw diameter was higher compared to those with a 4.5 mm screw diameter. A decrease in pilot hole diameter and an increase in the amount of epoxy resin provided higher screw withdrawal strength of materials. Using 20 % epoxy resin of the volume of the pilot hole resulted in two times better screw withdrawal strength values. The study showed that a higher amount of epoxy resin, smaller pilot hole diameter, and smaller screw diameter contribute to better screw withdrawal strength of both medium density fiberboard and particleboard from the face and edge.

Fields of residual stresses near open assemblage holes of aircraft wing panel

The results of fatigue tests of two geometrically identical and similar in design models of the lower wing panel of a commercial aircraft are were analyzed. The panels differed in the way of installing mounting bolts, which connect the skin and stringers. Cold expansion of holes drilled both in the skin and stringer has been performed for the first panel before joining. The second panel includes no additional treatment after drilling pilot holes and final reaming. Bolts are mounted with an interference fit varying from 1.3 to 2.1% and from 2.9 to 3.2% for the first and the second panel, respectively. Changes in the interference fit are the consequence of a scatter attributed to the presence of a tolerance zone for the diameters of both bolts and mounting holes. A two-step comparison of both technologies is based on the experimental study of residual stress fields. The first stage, being a subject of the present study, includes the analysis of residual stress fields, which arise after removing bolts and separation of skin from stringers. Hole drilling and gradual crack growth were used to determine the components of residual stresses. Deformation response is measured by electronic speckle-pattern interferometry. High quality interferograms, which provide a reliable resolution of the interference fringes of ultimate density over the hole edge or directly along the notch borders, have been obtained for both ways of local removing the material. The first point-wise method based on drilling a probe hole, provides a quantitative determination of the residual stress components, starting from 1.4 mm distance from the assemblage hole edge. The second technique implements the crack compliance method of subsequent lengthening of the notch, starting directly from the mounting hole edge. This approach provides for a quantitative analysis of residual stress fields, related to different bolt mounting technologies, proceeding from the comparison of SIF values. A high level of compressive residual stresses near open holes is characteristic for both types of panels. Both experimental approaches showed the benefits of joints, where bolts are mounted into cold-expanded (reinforced) holes. For this case, the estimation of the relaxation parameters of the principal component of residual stresses in the direction of the external load is presented.