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The swaging quality of self-lubricating spherical plain bearings (SSPBs) has an important influence on the safety of the aircraft. The roller swaging process has an edge on other swaging processes in low swaging load and high swaging quality. The 3D elastic–plastic finite element model of roller swaging and push-out test were developed, and the influence of the roller swaging process loading parameters, such as the swaging time, the swaging load and the rotation speed of the roller tool on the push-out load, the gap between the flanging lip of the V-groove and the housing chamfer, and the radial displacement (the inner surface of the outer ring) after roller swaging were studied. Finally, the roller swaging test was conducted, and the test results were compared with the simulation results. The research shows that the test results are consistent with the results of the simulation model, and with the increase of the swaging time, swaging load, and rotation speed of the roller tool, the gap will be increased as well, resulting in an increase in the push-out load. However, the excessive swaging load and rotation speed of the roller tool will increase the radial displacement, which will result in a reduction in the rotation flexibility of the bearing. Under the conditions of reasonable swaging time and swaging load, a good swaging quality can be obtained by controlling reasonable rotation speed of the roller tool.

For decades, attentions have been paid to metal cutting processes, especially for the critical components in aerospace, marine, medical industries, etc. Scholars investigated the influence of cutting parameters, tool geometry, lubricant, pursuing a deeper understanding of process signatures, better tool performance, and more superior surface integrity. Edge microgeometry is proved to be an essential factor that significantly influences the tool-workpiece-chip contact, plastic deformation, and heat generation, which in turn affects the cutting phenomena. This paper aims to provide an insight and scientific overview of the role of edge microgeometries in metal cutting, with special attention on material flow state, cutting mechanics, tool performance, as well as the surface integrity. The characterization of edge microgeometries includes edge types (honed, chamfered, mixed), size parameters (edge radius, form-factor K, chamfer angle, chamfer length), and edge preparation techniques (grinding, drag finishing, brushing, micro-blasting, etc.). The researches on the influence of edge microgeometries on material flow state and cutting mechanics are reviewed, mainly focusing on analytical modeling and finite element method to explain how the edge microgeometries affect cutting processes. Then, the researches on the influence of edge microgeometries on tool performance and surface integrity are well organized to present the various findings in these topics. From the current perspective, many scholars have noticed the importance of edge microgeometries in metal cutting and have done numerous researches on this topic. Summary and future suggestions are given based on their state-of-the-art contributions in the last section.

This work presents the results of the strength analysis of single lap riveted joints. In experimental investigations, performed in this paper, the blind rivet was considered. Blind riveted joints are very popular and often used in many branches as aerospace or automotive. In scientific publications is a research gap related to the strength analysis and failure mechanisms of the blind riveted joints. There are many geometrical parameters of riveted joints that have influence on strength parameters of the joint. One of them is the size of the chamfer located on the edge of the rivet hole. In this analysis a four different sizes of the hole chamfer were examined. The investigated specimens (sheets and the rivet) were made out of aluminium alloy. The tests of the blind rivet joints were performed with the use of a Zwick-Roell tension machine. As a results of experimental investigations, the ultimate shear load diagrams of joints were obtained. Obtained shear load diagrams showed influence of the hole chamfer size on destructive force of joint. Moreover, for a few joints the static test was interrupted before the damage of rivet. Next, the joints were covered by the epoxy resin. After that, the joints in an advanced stage of rivet deformation were cut and magnified using an optical microscope. Analysis of the rivet axial sections at various stages of deformation is an interesting task from the research point of view. Results obtained in this work contribute to a better understanding of the failure process of blind rivets.

Purpose This paper aims to propose a robotic automation system for processing special-shaped thin-walled workpieces, which includes a measurement part and a processing part. Design/methodology/approach In the measurement part, to efficiently and accurately realize the three-dimensional camera hand-eye calibration based on a large amount of measurement data, this paper improves the traditional probabilistic method. To solve the problem of time-consuming in the extraction of point cloud features, this paper proposes a point cloud feature extraction method based on seed points. In the processing part, the authors design a new type of chamfering tool. During the process, the robot adopts admittance control to perform compensation according to the feedback of four sensors mounted on the tool. Findings Experiments show that the proposed system can make the tool smoothly fit the chamfered edge during processing and the machined chamfer meets the processing requirements of 0.5 × 0.5 to 0.9 × 0.9 mm2. Practical implications The proposed design and approach can be applied on many types of special-shaped thin-walled parts. This will give a new solution for the automation integration problem in aerospace manufacturing. Originality/value A novel robotic automation system for processing special-shaped thin-walled workpieces is proposed and a new type of chamfering tool is designed. Furthermore, a more accurate probabilistic hand-eye calibration method and a more efficient point cloud extraction method are proposed, which are suitable for this system when comparing with the traditional methods.

Residual stresses play a vital role in determining the quality of the turned components. Numerical modelling of residual stresses provides a deep insight of the process mechanism and increases the productivity by conserving time, material and manpower. In parallel turning process, two tools are engaged simultaneously to perform the turning process. In this research work, numerical investigation was done to determine the influence of chamfer width and chamfer angle for various cutting speeds and feeds on the surface residual stresses. The numerical analysis was carried out utilising a software program, ABAQUS 6.14. The work and tool material are AISI 4340 steel and carbide. CPE4RT four node plane strain element was used for the analysis. The chip was separated from work material based on Johnson-Cook damage criterion. Surface friction between cutting tool and chip is modelled by employing penalty contact approach. The coefficient of friction was taken as 0.3. With the increase in chamfer angle and chamfer width, the surface residual stresses increase. This is caused due to the increase in cutting temperature and plastic strain. Maximum circumferential and axial compressive residual stress of 415 MPa and 445 MPa is obtained for a chamfer width of 0.2 mm. The cutting speed was 150 m/min and feed 0.1 mm/rev. On the whole, the usage of chamfered cutting tools proved to be beneficial in imparting higher compressive residual stresses in parallel turning process.

Objective: Research on evaluation of crowns made by the latest contemporary dental computer-aided design/computer-aided manufacturing (CAD/CAM) systems for their marginal adaptation is scarce. The purpose of this in vitro study was to evaluate the marginal integrity of crowns fabricated by the latest Chairside Economical Restorations of Esthetic Ceramic (CEREC) system using 2 different finish line preparation designs: chamfer and shoulder. Materials and Methods: Typodont teeth were divided equally into 2 groups, A and B. The teeth were prepared for full coverage crowns with a shoulder (group A) and chamfer (group B) finish line design. An experienced prosthodontist prepared all crown preparations. Evaluation of 6 sites per sample was completed by 2 calibrated, experienced prosthodontists using the modified US Public Health Services (USPHS) criteria. The descriptive statistics and Z-test were used to evaluate the results. Results: A total of 180 teeth were included in the study (90 teeth in each group). Only 2 crowns in group A and 1 crown in group B were clinically unacceptable. There was no statistical significance (p = 0.282) between the 2 groups regarding finish line design. Conclusions: The CEREC system provides clinically acceptable crowns and can safely be utilized in dental treatment. Therefore, CAD/CAM restorations could be considered as a safe treatment modality by dental professionals.

Статья является логическим продолжением первой части (№1, 2020), в которой была предложена методика геометрического моделирования кромок отверстий на цилиндрических участках обечаек. В этой части рассмотрено математическое описание кромок отверстий в сферических и конических участках корпусов. Показано, что поверхность кромки отверстий может быть описана как дважды косой цилиндроид или косой коноид в зависимости от требований к разделке.Полученные выражения для описания кромок отверстий могут быть представлены в аналитическом и матричном виде (в однородных координатах). Также полученные выражения могут быть использованы в качестве промежуточного этапа в предложенной методике проектирования технологических комплексов. Отмечено, что получаемую криволинейную направляющую разделки кромки можно использовать в качестве связи между обрабатываемым изделием и обрабатывающим инструментом для механической обработки кромок отверстий с помощью нестационарных технологических комплексов. The article is a logical continuation of the first part (No. 1, 2020), in which a method for geometric modeling of hole grooves on cylindrical sections of shells has been proposed. Mathematical description of hole grooves in spherical and conical sections of hulls has been studied in the current part. It is shown that surface of a hole groove can be described as double oblique cylindroid or oblique conoid depending on groove preparation. Received expressions for describing the hole grooves can be shown in analytical and matrix form (in uniform coordinates). Also received expressions can be used as an intermediate stage in the proposed methodology for the design of process systems. It is noted that the resulting curvilinear groove guide can be used as a connection between the workpiece and the machining tool for machining the hole grooves using non-stationary process systems.

Higher yttria content enhances the translucency and appearance of dental zirconia materials. Alterations in material composition also affect mechanical properties. The aim of this study was to compare the fracture load after artificial short-term aging of monolithic, full-contour zirconia crowns with different amounts of yttria-stabilization. Sixty crowns (thirty super high translucent crowns (5Y-Z) and thirty high translucent crowns (3Y-Z)) were produced to fit a model of a premolar with a shallow chamfer preparation. The crowns were cemented with self-adhesive resin cement on composite abutments. For each zirconia type, three groups of crowns (n = 10) were allocated to: (i) cyclic loading (200 N, 1 Hz, 30,000 cycles), (ii) hydrothermal aging (3 × 20 min, 134°C 3.2 bar), or (iii) no treatment (control). Surviving crowns from the aging process were quasistatically loaded until fracture. The 3Y-Z crowns had statistically significantly higher fracture values (3,449 N) than the 5Y-Z crowns (1,938 N). The aging procedures did not affect load at fracture. Fractographic analysis showed that fractures started either at the crown margin or at the occlusal intaglio area. Higher yttria content leads to a reduction in material strength and damage tolerance, and this should be reflected in recommendations for clinical use.

The ideal room temperature will create comfort in the learning and teaching process. With increasing outdoor air temperature due to climate change, an air conditioner is needed to reach the ideal room temperature. An air conditioner is an air conditioner that is needed to regulate the temperature and humidity of the air in a room. The purpose of this study is to determine the airflow pattern produced by air conditioning equipment and to determine the distribution of air temperature in the computer laboratory room. Computational Fluid Dynamic (CFD) is a simulation method used by using the ANSYS application. Based on research conducted in a computer laboratory room which has a length of 12 m, a width of 12 m, a chamfer of 3.93 m and a height of 3 m, the airflow pattern produced by the air conditioner is relatively the same between the variable air velocity 2.5 m / s and 3 m / s. Where the air will move straight in accordance with the outlet shape of the air conditioner and then experience a decrease in speed over a certain distance and a change in the direction of air flow occurs due to exposure to room properties and eventually spreads throughout the room. The average temperature in the computer laboratory room for the variable air velocity 2.5 m/s is 24 ° C. Meanwhile, the variable air velocity 3 m/s 23 ° C.

Researches on the modeling of machining difficult-to-cut metals are important for optimization of the processing parameters, in which the force modeling is essential due to its significant influence on the performance of tools and the quality of parts. A semi-analytical method for force prediction in orthogonal cutting with chamfered tools considering both edge and size effect is proposed in this paper. The plastic deformation in the shear band was investigated using a parallel shear zone model and unequal division shear zone model. The influence of size effect on cutting force was discussed and a simplified expression of improvement factor is introduced to describe the sharp increase of shear stress under the condition of low feed rate. Simulations of orthogonal cutting with different chamfer lengths are conducted to analyze the variation of cutting force with respect to chamfer length, which reveals that the influence of chamfer length on cutting force is determined by the ratio of chamfer length to uncut chip thickness. A modified function considering the trend of material flow condition is proposed, which treats the total cutting force as a combination of cutting forces caused by chamfered edge and rake face. The calibration of constants in the proposed method is achieved using particle swarm optimization (PSO), a meta-heuristic algorithm for complicated non-linear models. The experiments show that the method works well on both fitting and predicting modules in orthogonal cutting of AISI 304 using cemented carbide tools with 15° chamfer angle or 25° chamfer angle.

A novel wideband circularly polarized (CP) magneto-electric (ME) dipole 1 × 2 antenna array for millimeter-wave applications is presented in this paper. The magneto-electric dipole of a single radiator is designed by combining a pair of loaded short-circuited metallic patches acting as electric dipole with a bowtie-shape aperture and a pair of vertical metallic posts functioned as a magnetic dipole. The pair of metallic patches is fed by the bowtie-shape aperture etched on the top surface of shorted-end substrate integrated waveguide (SIW). By chamfering and adding perturbation on each rectangular patch, the proposed ME dipole antenna realizes circular polarization radiation. Measured results show that the proposed single radiator has an impedance bandwidth of 27.1% (24.29 to 31.9GHz) for S11

This article evaluated the sealing capacity of single crowns made of a new zirconia (Katana STML, Kuraray Noritake) when cemented with two different cement types and two different marginal preparation types. Forty intact human anterior teeth, extracted for periodontal reasons, were used. Each sample was prepared with two margin preparations: knife-edge (KE) on one half of the tooth and chamfer (CH) on the other half. Based on the type of cement used, abutments were randomly distributed into one of two groups: Group 1 used resin cement (Panavia V5, Kuraray Noritake), and Group 2 used reinforced glass-ionomer cement (FujiCEM 2, GC). A digital workflow was utilized for crown fabrication. After the cementing procedures, samples were processed, and microleakage and scanning electron microscopic observations were made. Microleakage varied significantly depending on the type of cement combination used. Group 1 samples showed less microleakage (medians: 0.76 for CH and 0.51 for KE in Group 1, and 4.1 and 3.45 for Group 2, respectively) than Group 2 specimens; the difference was statistically significant (P < .000). KE preparation showed less microleakage than CH, although no statistically significant differences were found (P < .0558). Under microscopic observations, some samples showed internal fractures within the zirconia material. KE and CH seal the margin of zirconia crowns similarly. The resin cement system ensured better adhesion than reinforced glass-ionomer cement.

AIM: To evaluate and compare the effect of enamel preparation designs bevel, chamfer and stair-step chamfer on the fracture resistance of nanocomposite. METHODS: The sample group of this study consisted of 72 non-carious permanent maxillary central incisors. The sample is divided into four groups of 18 each. Group, I control Group II bevel preparation, Group III chamfer preparation, group IV stair step chamfer preparation. After the specific preparation, each tooth is filled with nanocomposite using bulk pack technique. The teeth were subjected to fracture resistance test under Universal testing machine and then were examined under a stereomicroscope to evaluate the type of bond failure. The results were subjected to statistical analysis. RESULTS: Results of the One-Way ANOVA revealed a significant difference in the mean peak failure load values of the four different groups. (P < 0.001) Tukey’s Post-Hoc comparison test revealed that there was a significant difference in the mean peak failure load values of the bevel and chamfer preparation. But there was no significant difference between chamfer and stair-step chamfer preparation designs. CONCLUSION: Stair-step chamfer preparation demonstrated comparable values to Chamfer preparation but also involved the removal of less amount of tooth structure adjacent to the fractured edge and good esthetic technique.

The edge-curved ice spoon is a wooden tool to eat ice cream, and the machine tool adopted to chamfer and deburr the unformed curved edge ice spoon is called surface-taking machine (chamfering machine). In the course of cutting, the results are primarily dependent on the speed of cutter shaft. In order to guarantee the quality of the spoon, scraping-edge device of the surface-taking machine is anatomized and designed, and the working principle of the surface picking machine is introduced. The cutting force is analyzed from theoretical and experiential perspectives. The device is modeled in the SolidWorks and simulated by ADAMS to attain time-varying curves of scraping-edge device displacement and contact force of the cam and wheel. The modal analysis of the cutter shaft is carried out on ANSYS Workbench, the vibration frequency and vibration mode of the former six steps are attained, and the critical speed of the cutter shaft is calculated to determine the rotational speed of the cutter shaft, which effectively avoids the resonance zone and ensures the effective operation of device. Additionally, the actual production and processing are able to lay a theoretical basis.

To investigate the seismic performance of railway bridge piers with round-ended hollow section, five 1/6-scale specimens were tested under low-cyclic loading. The two variable parameters were the volumetric stirrup ratio and axial load level. The damage evolution, strain response, and plastic hinge behavior were meticulously explored. The load-drift relationship, displacement ductility, strength/stiffness degradation, dissipated energy, and viscous damping were analyzed in depth. The quantification of seismic performance objectives was implemented by displacement ductility based on damage assessment. The relationships among the ductility and strength/stiffness degradation and equivalent damping ratio were regressed using the test data. The experiment and analysis results showed that all specimens suffered flexural failure, with flexural cracks covering nearly two-thirds of the pier height. The plastic hinge region lengthened and moved upwards along the column due to the existence of solid segment, internal chamfer and variable section. The displacement ductility capacity enhanced noticeably with increasing stirrup ratio. The increasing axial compression ratio led to higher initial stiffness and seismic capacity to some extent, but excessive axial load would decrease ductility with premature concrete crushing. Furthermore, the seismic safety of the piers were ensured under a ductility factor limitation of 4.8 required by the current seismic code for railway engineering of China.

Beam-column joints (“BCJ”) are critical members in low-rise to mid-rise buildings. Failure of BCJ may lead to collapse of building. To strengthen non-seismically designed BCJ, a comprehensive study has been commissioned to develop a strengthening strategy for BCJ using unsymmetrical chamfers. Specifically, chamfers are proposed to be installed at beam-column corners and under the soffit only to alleviate the undesirable joint-shear failure. Tests were carried out on four 2/3-scale BCJ, comprising one control specimen and three strengthened specimens including 300 mm chamfers with and without U-bars and 150 mm chamfers with U-bars. The specimens were subjected to moderate level of axial load and loaded to failure under quasi-static cyclic loading. It has been shown that unsymmetrical chamfers are effective to protect a non-seismically designed BCJ against failure at joint core. Mode of failure is shifted from joint-shear in the control specimen to column-flexure in the strengthened specimens. To enhance the performance of BCJ, size of chamfer is more crucial in comparison with providing reinforcements inside the chamfers.

A reasonable coupled triggering mechanism has greater potential to produce a progressive crushing mode and improve the crashworthiness of composite absorbers. To clearly understand coupled triggering mechanisms, the crashworthiness of composite tubes triggered by double- and triple-coupled triggers is comprehensively evaluated. Five double-coupled triggers including chamfer/hole, chamfer/slit, chamfer/saw tooth, chamfer/plug, and chamfer/material degradation (C-GMD) triggers are designed. To exhibit better crashworthiness, triple-coupled triggers are designed by coupling each double-coupled trigger with a plug trigger. Based on Finite Element Methods (FEM), comparisons of the crashworthiness of tubes using double- and triple-coupled triggers are conducted. Effects of width and height of plug on failure modes are further studied. From the predicted results, coupled triggering and energy-absorbing mechanisms are extensively revealed. Double-coupled triggers further weaken triggered regions to reduce the initial peak while triple-coupled triggered tubes improve Energy-Absorption (EA). Triple-coupled C-GMD-plug trigger presents 26.62% higher EA than C-GMD trigger. Material folding and buckling mechanisms have great effects on the material accumulating process. Failure modes are highly sensitive to plug width, plug height and a combination of both. Some design proposals for C-GMD-plug trigger are recommended.

Now, the static push-the-bit rotary steerable system (SRSS) developed in China is being put into field tests and primary applications. During its normal drilling, higher frictional forces generated by the static pushing forces of the rotary ribs on the wellbore wall influence the weight-on-bit (WOB) transmission efficiency and the rate of penetration (ROP). In this paper, analytical models of the WOB transmission efficiency were established for the wellbore wall with and without ladders respectively based on the structure and working principle of the SRSS. And the variation rules of the WOB transmission efficiency with the nominal WOB, the frictional coefficient of wellbore wall, the pushing force and the front chamfer of the steerable rib were analyzed. And the following research results were obtained. First, the nominal WOB of this SRSS has to satisfy the minimum requirement and it is conducive to the increase of WOB transmission efficiency by increasing the nominal WOB appropriately. Second, whether there are ladders on the wellbore wall or not, the WOB transmission efficiency decreases as the total pushing forces of steerable ribs and the frictional coefficient of wellbore wall increase. And the WOB transmission efficiency in the case of wellbore wall with ladders is much lower than that without ladders. Third, if there are ladders on the wellbore wall, the front chamfer of steerable rib has a significant effect on the WOB transmission efficiency. The larger the front chamfer is, the lower the WOB transmission efficiency is (even self-locking). In conclusion, the research results play an important role in guiding the rational selection and control of the WOB at drilling site. Keywords: Rotary steerable system (RSS), Static push-the-bit, Weight-on-bit (WOB), Transmission efficiency, Self-locking of steerable rib, Frictional coefficient of wellbore wall, Pushing force of the steerable rib

Objectives: To study influence of different designs of zirconia substructures on color and fracture resistance in bilayered zirconia CAD CAM restorations.Materials and Methods: Fifty identical PMMA dies were 3D printed using stereolithography, to mimic a prepared maxillary first molar with chamfer finish line of 1 mm, axial reduction of 1.5 mm and occlusal preparation of 2 mm. CAD CAM (Wieland dental) was used to digitally scan the fifty dies in order to fabricate 50 zirconia copings. They were assigned to 5 groups according to coping design (n=10): Gp FV (control): full-veneer coping covering to finish line, Gp CS: 1mm cervical-shoulder, GP BW: monolithic zirconia with window cut-back on the buccal surface, GP 3W: monolithic zirconia with window cut-back on buccal, lingual and mesial surfaces and Gp MM: circular projections of 1 mm on palatal cusps and mid-palatal surface. All copings were then veneered, air-abraded using 50μm- Al2O3, primed and cemented to their matching dies using resin cement (Rely X U200, 3M-ESPE). Specimens were tagged and thermo-cycled for 10000 cycles. Spectrophotometer (Easy Shade V, VITA Zahnfabrik) was used to digitally analyze the color for all groups. Delta E was calculated in-comparison to the control group. Compressive load was applied to all specimens in the central fossa, parallel to long axis of each die at a crosshead speed of 0.5 mm/min till failure. Level of significance between groups was calculated using One Way ANOVA (P

Because of its ability to capture hard structures behind soft tissue, ultrasound-based micro-scanning may be a promising alternative for taking digital impressions of teeth, especially in the case of subgingival margin preparations. The aim of this study was to assess the accuracy of ultrasound impressions taken of subgingivally prepared teeth compared with digital optical impressions. Ten extracted human teeth (7 pre-molars, 3 molars) were prepared for crowns with chamfer finish line and then digitized using two different intra-oral scanners (Cara Trios, 3 Shape, Heraeus Kulzer, Hanau, Germany; and Lava COS; 3M ESPE, Seefeld, Germany) and one extra-oral scanner (Cares CS2, Straumann, Basel, Switzerland). Afterward, the preparation margin was covered with porcine gingiva (thickness ranged between 0.3 and 0.9 mm), and every sample was scanned with a high-frequency ultrasound scanner under experimental subgingival conditions. Optical scanning processes were performed without gingiva. The data sets were superimposed on each other for pairwise comparisons, and deviations between different scans were determined using a 3-D evaluation software (CloudCompare). Kruskal-Wallis and post hoc tests (Dunn-Bonferroni) were applied to detect significant differences at p ≤ 0.05. The ultrasound scanner was able to detect subgingival preparation margins. Mean deviations for all comparisons ranged from 12.34 to 46.38 µm. There were no statistically significant differences between superimpositions of intra-oral and extra-oral scans (Trios-Lava, Lava-CS2, Trios-CS2), whereas in comparisons between intra-/extra-oral scans and ultrasound scans, mean deviations were statistically significantly higher. There were no significant differences with respect to type of tooth (pre-molar and molar). However, gingiva thickness was significantly correlated with the quality of the ultrasound scan; thin layers had better image quality than thicker layers. Ultrasound was able to scan tooth preparation margins covered with gingiva, although with less accuracy than achieved by conventional optical scanners (non-covered margins). Gingiva thickness may play an important role in ultrasound scan accuracy.

Aim: The aim of the study was to compare the assessment methods used to evaluate the fit of Ni-Cr metal copings. Settings and Design: Comparative- Invitro study design. Materials and Methods: A stainless steel die simulating a prepared first maxillary premolar was used as a master die. Wax pattern copings were fabricated by the conventional dipping wax technique (n = 20) on the master die and were cast in Ni-Cr alloy. The finished copings were fitted on the master die and scanned by the micro-computed tomography (CT) scanner. Multiple projections of the sample were reconstructed to evaluate the marginal and internal fit at 5 predetermined locations. The same copings were used for the replica technique and were evaluated under a stereomicroscope in the same locations. Statistical Analysis Used: Shapiro–Wilk's test and Unpaired t-test Results: The marginal fit values observed were 127.71 and 95.06 μm, chamfer area fit values were 151.97 and 132.7 μm, axial area fit values were 62.36 and 46.14 μm, axio-occlusal area fit values were 139.52 and 123.6 μm, occlusal area fit values were slightly higher with 217.91 and 193.1 μm, respectively, in replica and micro-CT technique. There was no statistically significant difference observed in the fit between the two assessment methods (α > 0.05). Conclusions: There was no difference observed in the marginal and internal fit of Ni-Cr metal copings with the two methods of assessment. However, the micro-CT technique proved to be simpler, noninvasive, and time-saving assessment method.

An experimental correlation showing flipchip packaged larger dies more susceptible to corner delamination is, first, established in this work. Chamfer structures have been inserted into the architecture of traditional orthogonal crackstop designs with the aim to alleviate the accumulation of strains present in the corners of larger dies. Finite element modeling (FEM) was employed to uncover the optimum chamfer structure size that minimizes both the chamfer space usage as well as chip package interaction (CPI) related risks. Die size was shown to have quantifiable impact on the corner strain. The effect of die size was shown to be enhanced with lower underfill modulus. The effect of changing the crackstop corner chamfer structure size on both corner strain and strain energy release rate was studied. While varying the crackstop corner chamfer structure size had minimal effect on strain, it did have a significant effect on the strain energy release rate. It was observed that chamfer structure significantly reduces the strain energy release rate at the edge of the die near the corner. It has been determined that the optimum location for the support structure triangle vertex is to be situated at the point where the peeling strain switches from compressive to tensile at the corner square. The effectiveness of corner chamfer support structures in reducing CPI risk at the optical attach cavity used for lateral optical fiber attach was evaluated. The simulations have determined that inclusion of crackstop corner support structures at the newly created internal cavity corners of the die result in a reduction of the average corner strain by 33% at the external corner and 21% at the internal corner of the optical cavity.

With the majority of research, in relation to 3D object reconstruction, focusing on single static synthetic object reconstruction, there is a need for a method capable of reconstructing morphing objects in dynamic scenes without external influence. However, such research requires a time-consuming creation of real world object ground truths. To solve this, we propose a novel three-staged deep adversarial neural network architecture capable of denoising and refining real-world depth sensor input for full human body posture reconstruction. The proposed network has achieved Earth Mover and Chamfer distances of 0.059 and 0.079 on synthetic datasets, respectively, which indicates on-par experimental results with other approaches, in addition to the ability of reconstructing from maskless real world depth frames. Additional visual inspection to the reconstructed pointclouds has shown that the suggested approach manages to deal with the majority of the real world depth sensor noise, with the exception of large deformities to the depth field.

This paper presents a new machinable 90° waveguide twist design suitable for broadband applications from microwave to terahertz. The polarization direction is deflected 90° by integrating a Two-square waveguide with chamfer between the H-plane and E-plane waveguides. All right angles in the circuit are rounded, and after tolerance analysis, this design can be used to computer numerical control (CNC) machining. The simulation results show that the return loss is better than 20dB in 190260GHz frequency band. Using WR4.3 vector network analyzer test, the actual return loss in 190-260GHz is better than 15dB, fully meet the requirements of practical application. Key words: terahertz, waveguide twist, microwave millimeter wave.

Background We investigated the accuracy and safety of a new HURWA robotic-assisted total knee arthroplasty (TKA) system in a sheep model. Methods Ten male Small-tailed Han sheep were used in this study. Sheep were imaged by computed tomography scan before and after bone resection and the cutting errors between actual bone preparation and preoperative planning of the femur and tibia in 3 dimensions were measured . Results The overall accuracies after surgery compared with that from preoperative surgical planning of the left and right femurs were 1.93±1.02° and 1.93±1.23°, respectively. Additionally, similarly high overall accuracies for the left and right tibia of 1.26±1.04 and 1.68±0.92°, respectively, were obtained. The gap distances of the distal cut, anterior chamfer, anterior cut, posterior chamfer, and posterior cut on the medial side were 0.47±0.35 mm, 0.41±0.37 mm, 0.12±0.26 mm, 0.41±0.44 mm, and 0.12±0.23 mm, respectively. No intraoperative complications, such as intraoperative fracture, massive bleeding or death, occurred CONCLUSION: This new HURWA robotic-assisted TKA system is an accurate and safe tool for TKA surgery based on the sheep model. This article is protected by copyright. All rights reserved.

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We report on ultrashort pulsed laser fabrication strategies for glass articles with customized edges and curved surfaces. To achieve single-pass, full-thickness modifications along the entire substrate processing optics are presented that allows for beam shaping of non-diffracting beams and, additionally, for aberration compensation of phase distortions occurring at the tilted or curved interfaces. The efficacy of our concepts is presented by evaluating the surface and edge qualities of separated glass tubes with complex inner and outer contours as well as glass chamfer structures.

Bioinspired dynamic structural color has great potential for use in dynamic displays, sensors, cryptography, and camouflage. However, it is quite rare for artificial structural color devices to withstand thousands of cycles. Male hummingbird's crowns and gorgets are brightly colored, demonstrating frequent color switching that is induced by regulating the orientation of the feathers through movement of skin or joints. Inspired by this unique structural color modulation, we demonstrate a flexible, mechanically triggered color switchable sheet based on a photonic crystal (PhC)-coated polydimethylsiloxane (PDMS) kirigami (PhC-PDMS kirigami) made by laser cutting. Finite element modeling (FEM) simulation reveals that the thickness of PDMS kirigami and the chamfer at the incision induced by laser cutting both dominate the out-of-plane deformation through in-plane stretching. The bioinspired PhC-PDMS kirigami shows precisely programmable structural color and keeps the color very well after recycling over 10 000 times. This bioinspired PhC-PDMS kirigami also shows excellent viewability even in bright sunlight, high readability, robust functionality, technical flexibility, and mechanical durability, which are readily exploitable for applications, such as chromic mechanical monitors for the sports industry or for medical applications, wearable camouflage, and security systems.

Background: Marginal and internal fit are believed to be one of the most important guideline in the assessment of ceramic restorations and are one of the most remarkable requirement for the long-term performance of fixed dental prostheses. PURPOSE: Was to evaluate the influence of different CAD-CAM systems on the marginal and internal adaptation of hybrid ceramic restorations. Materials and Methods: Lower right six of a typodont resin cast with a 1.0 mm circumferential chamfer finish line, an occlusal reduction of 2.0 mm, and an average of 10-12° convergence angle was prepared. This master die was duplicated to thirty acrylic resin dies milled from PMMA discs using CAD-CAM technique. Vita Enamic monolithic crowns were manufactured using three different CAD-CAM systems Ceramill, Zirkonzahn and CEREC InLab systems (n=10). Replica technique procedure was used to assess marginal and internal fit of the fabricated prostheses by measuring the thickness of light body impression material between the master die and the restoration at five points using digital microscope. Results: Measurements were collected for each group and appropriate statistical analysis was carried out. Conclusion: CEREC system showed relatively lower marginal and internal discrepancy in a comparison with the other systems. Therefore, there is a significant difference among the three systems.

Aims of Study: to evaluate and compare the retentive strength and the failure-modes of monolithic zirconiacrowns with different cement spacer thickness, cemented with two different types of luting agents.Materials and Methods: Forty sound maxillary first premolar teeth were divided into two main groups(n=20): Group A: cement spacer thickness of 80?m; Group B: cement spacer thickness of 120?m. Thegroups were further subdivided into two subgroups (n=10): (A1, B1) cemented with Panavia F2.0 resincement; (A2, B2) cemented with Riva luting plus RMGIC. All the teeth were prepared to receive monolithiczirconia crowns with the following features: (6o convergence angle, 0.8mm deep chamfer finishing line,4mm axial wall height with planar occlusal reduction). Afterwards, the teeth were scanned and the crownswere fabricated and cemented. Zirconia crowns were pulled-out along its path of insertion using universaltesting machine. Failure stresses were calculated in MPa. Failure-modes was assessed using magnifyinglens (2.5X).Results: The highest mean retentive values (in Mpa) was recorded by subgroup B1 (8.651); followed bysubgroup B2 (7.765); subgroup A1 (7.309) and subgroup A2 (6.875). Independent t-test showed a statisticallysignificant difference between A1 and B1 subgroups. Concerning the failure-mode, the majority of samplesrevealed adhesive failure between teeth and cement.Conclusion: All the tested crowns have mean retentive values within the clinically acceptable limit,increasing cement space resulted in a significant increase in the retention when Panavia F2.0 used as a lutingagent, while, it has no significant effect on the retention when RIVA luting plus was used.

The intent of this chapter is (i) to review the major chamfering and deburring possibilities currently available on the market and (ii) to present how off-the-shelf tools can be used on a 5, 4+1 or 4 Axis CnC machine to do part or all of the chamfering for a given gear production. The installation of End Mill, Ball Mill, Conical Side Milling and Chamfer tools is presented with the issues to consider in terms of interference and collision risks.

In this paper, we present a novel deep architecture to recover a 3D shape in triangular mesh from a single image based on mesh deformation. Most existing deformationbased methods produce uniform mesh predictions by repeatedly applying global subdivision but fail to require the highlighted details due to the memory limits. To address this problem, we propose a novel saliency guided subdivision method to achieve the trade-off between detail generation and memory consumption. Instead of using local geometric cues such as curvature, we introduce a global point-based saliency voting operation to guide the adaptive mesh subdivision and deformation explicitly. Moreover, we propose the oriented chamfer loss to mitigate the mesh self-intersection problem in subdivision. We further make our network configurable and explore the best structure combination. Extensive experiments show that our method can both produce visually pleasing results with fine details and achieve better performance compared to other state-of-the-art methods.

Objective: The purpose of this study was to evaluate the effect of finish line design and cement space thickness on the marginal accuracy of monolithic zirconia crowns. Materials and methods: Thirty crowns were fabricated from translucent zirconia (inCoris TZI) using Cerec in-Lab system and divided into three main groups (10 each) according to the finish line type of the die (knife-edge, chamfer, and shoulder). Every group was divided into two subgroups (5 each) according to cement space thickness (20 and50?m). Optical impressions were taken for the dies using the Cerec scanner and cement space was set twice for every finish line design; 20 and 50 ?m. The completed crowns were cemented to the dies and the marginal gap was evaluated. The collected data was statistically analyzed using Mann-Whitney U test and Kruskal-Wallis test and the significance level was set at P ? 0.05. Results: Regarding the marginal gap; there was no statistically significant difference between different finish line designs or between different cement space thicknesses. Conclusion: Neither finish line design nor cement space thickness has an effect on the marginal gap of inCoris TZI crowns.KeywordsCement space; Finish line; Marginal fit; Monolithic zirconia.

Subgingival margins are often associated with adverse periodontal reactions, such as recession and gingival inflammation. The purpose of this cross-sectional dual-center study was to evaluate the periodontal health and stability of intrasulcular margins, comparing two prosthetic margin preparations: subgingival chamfer (SC) and subgingival feather-edge (SF) with gingival curettage. Ninety-six patients with 205 crowns (buccal margin 0.5 mm into the gingival sulcus) were included in the study. SF, gingival curettage, and intrasulcular restorative margin were prepared on 109 crowns; SC was prepared on 96. Restorations were in place for a mean of 55.9 months (range: 12 months to 10 years). No significant differences were found regarding probing depth between the two groups (mean buccal: 1.6 mm; mean interproximal: 2.3 mm). Significant increased recession was present around SCs, showing a higher margin-exposure frequency (buccal: 19.8% vs 3.7%; interproximal: 5.2% vs 1.4%). SC showed 8.5 times the risk of margin exposure compared to SF, men 5.5 times compared to women, and smokers 3.7 times compared to nonsmokers. Follow-up time was not a significant factor. SC sites showed a tendency for reduced buccal bleeding on probing compared to SF sites (3.0% vs 12.1%), but no significant difference was seen in a regression model. Plaque presence increased the risk of bleeding (4.1×), and women presented a higher risk of bleeding than men (3×). Subgingival margins can provide adequate periodontal health and stability if restorative procedures are well controlled and if patients are enrolled in an adequate maintenance program. SF with intrasulcular margin favors facial soft tissue stability, as reduced gingival recession was observed. The technique should be carefully applied to promote an adequate periodontal response.

The rectangular sealing ring mainly used in static sealing structure is usually subject to sealing failure, permanent deformation and other problems in practical use. The two-dimensional axis-symmetrical finite element analytical model of rectangular sealing ring during working is established to deal with the above prominent problems based on Von Mises yield principle, virtual work principle, axial symmetry principle and nonlinear contact theory, and orthogonal optimization is used to optimize the key structural parameters of rectangular sealing ring such as section width, section thickness and chamfer size to acquire the optimal combination scheme for key parameters of sealing ring, and contrastive analysis is done on the mechanical property of sealing ring before and after optimization. The research results indicate that: First the ranking of the factors affecting the performance of rectangular sealing ring in descending order is: section width, chamfer size, section thickness; Second the optimal combination for key structural parameters of rectangular sealing ring is: section width of 4 mm, section thickness of 3.5 mm, and chamfer size of 0.3 mm; Third compared with that before optimization, the maximum contact stress of rectangular sealing ring after optimization is improved by 21.87% on average, amount of compression reduced by 11.59% on average, and the maximum Mises stress increased only by 7.72% on average; fourth under the same axial assembly force, the optimized rectangular sealing ring has the contact stress increased, the amount of compression reduced and the risk of permanent deformation lowered; Fifth, Mises stress and contact stress of the optimized rectangular sealing ring are uniformly distributed, beneficial to improving the sealing performance. According to the conclusion, the rectangular sealing ring after parameter optimization can better satisfy the requirements on sealing performance and avoid permanent deformation.

Wind turbines are under continuous development for large-scale deployment and oceanization, leading to the requirement of longer blades. The economic losses caused by blade replacement and shutdown have increased. The downtime caused by blade issues in a wind turbine is 8&ndash, 20% of the total downtime. Many of these blade issues originate from the cracking of the blade trailing edge. The edge is more susceptible to damage due to the complex geometry, manufacturing technique, and operation conditions. The traditional design method and the expensive experimental research are not suitable for the accurate damage analysis of the trailing-edge adhesive because of simplifying assumptions and costs. This study aimed to investigate the influence of trailing-edge structural configurations on the shear fatigue life of the trailing-edge adhesive joint using finite element and stress transformation matrix (STM) methods. The structural configurations of the blade trailing edge included the position of unidirectional fiber layer (UD), chamfer of bonding line, prefabricated components, and outer over-lamination of the trailing edge. In this study, the finite element method was used to simulate the blade structure. The shell element was used for laminates, and the solid element was used for the trailing-edge adhesive joint. The basic shear fatigue properties of the adhesive were obtained by standard component tests. The shear fatigue life of the blade trailing-edge adhesive joint under given load conditions was calculated using the fatigue properties of the adhesive and STM method. The results showed that the angle of chamfering, location of UD, rigidity of the preform, and outer over-lamination all had an obvious influence on the fatigue damage of trailing-edge adhesive. The findings of this study can be used to guide blade structure design and blade production and maintenance.

BACKGROUND The purpose of this study was to analyze pulpal temperature increase generated by prosthodontic margin repositioning and finishing with ultrasonic and rotating instruments. The temperature changes recorded were also correlated with the residual dentin thickness. METHODS A sample of 32 human extracted molars was selected. The teeth were endodontically treated and prepared with prosthetic round chamfer preparation. Then, they were inserted in plaster cubes up to the cement-enamel junction, leaving the apical portion pervious for inserting the thermocouple probe. The conventional technique, which involves the use of a high-speed contra-angle handpiece, was compared with an ultrasonic method (Crown Prep, Mectron, Carasco, Italy). For margin repositioning and finishing, two walls were randomly selected for each tooth: one was included in the test group and cut with the piezoelectric instrument (Multipiezo Touch TipHolder DB2, Mectron, Carasco, Genoa, Italy), the other one was inserted in the control group and cut with the high speed contra-angle handpiece (Kavo, Biberach, Germany). To standardize the operator-dependent parameters, it was used a mechanical arm controlled by a computer. These parameters were the pressure exerted on the dental wall, the cutting length and the time required for margin repositioning and finishing. For both test and control group, test phase consisted in a first stage of margin repositioning using an ultrasound tip or a diamond bur with a greater granulometry (120 µm for the ultrasound tip and 125 µm for the diamond bur), followed by a second finishing step conducted by an ultrasound tip or a diamond bur with smaller granulometry (60 µm for the ultrasound tip and 30 µm for the diamond bur). During these stages the intrapulpal temperature was recorded thanks to a thermocouple. Before and after these steps, the thickness of the remaining dental walls was measured with a caliber. RESULTS The average pulpal temperature increase was 5.03±0.98 °C for the ultrasonic preparation (test group) and 3.55±0.95 °C for the conventional technique (control group). The difference was statistically significant (P value

Aging building structure has become a world problem. This problem is particularly serious in developing and underdeveloped countries. The multihazard resilience and sustainability (e.g., seismic performance) decrease at the aging building. A construction method for strengthening aging-reinforced concrete buildings by wrapping structural members with carbon fiber sheets has been proposed and implemented in recent years. Authors aim to develop a seismic retrofitting method of aging concrete structural wall with a rectangular cross section using carbon fiber sheets. In this paper, authors examined the stress-strain relationship of concrete elements with rectangular cross sections reinforced by wrapping with carbon fiber sheets. Monotonic uniaxial compression tests were performed on 21 specimens using the ratio of the long side to the short side and the ratio of the element height to the short side of the concrete cross section, the weight of the carbon fiber sheet, and the chamfer radius of section corners as variables. The tests revealed that (1) the compressive strength decreases and ultimate strain increases as the ratio of the long to short side (longitudinal ratio) of the cross section increases even in a range the ratio exceeds 2 and (2) the ratio of the element height to the short side does not significantly affect the stress-strain relationship. Furthermore, authors proposed evaluation formulas for the constitutive law of concrete elements with rectangular cross sections including the longitudinal ratio which exceeds 2 reinforced by carbon fiber sheets and confirmed that the formulas can reproduce the test results with good accuracy.

We introduce a differential visual similarity metric to train deep neural networks for 3D reconstruction, aimed at improving reconstruction quality. The metric compares two 3D shapes by measuring distances between multi-view images differentiably rendered from the shapes. Importantly, the image-space distance is also differentiable and measures visual similarity, rather than pixel-wise distortion. Specifically, the similarity is defined by mean-squared errors over HardNet features computed from probabilistic keypoint maps of the compared images. Our differential visual shape similarity metric can be easily plugged into various 3D reconstruction networks, replacing their distortion-based losses, such as Chamfer or Earth Mover distances, so as to optimize the network weights to produce reconstructions with better structural fidelity and visual quality. We demonstrate this both objectively, using well-known shape metrics for retrieval and classification tasks that are independent from our new metric, and subjectively through a perceptual study.

PURPOSE To: (1) determine which preparation techniques clinicians use in routine clinical practice for single-unit crown restorations; (2) test whether certain practice, dentist, and patient characteristics are significantly associated with these techniques. MATERIALS AND METHODS Dentists in the National Dental Practice-Based Research Network participated in a questionnaire regarding preparation techniques, dental equipment used for single-unit crown preparations, scheduled chair time, occlusal clearance determination, location of finish lines, magnification during preparation, supplemental lighting, shade selection, use of intraoral photographs, and trimming dies. Survey responses were compared by dentist and practice characteristics using ANOVA. RESULTS Of the 2132 eligible dentists, 1777 (83%) responded to the survey. The top two margin configuration choices for single-unit crown preparation for posterior crowns were chamfer/heavy chamfer (65%) and shoulder (23%). For anterior crowns, the most prevalent choices were the chamfer (54%) and the shoulder (37%) configurations. Regarding shade selection, a combination of dentist, assistant, and patient input was used to select anterior shades 59% of the time. Photographs are used to communicate shade selection with the laboratory in about half of esthetically demanding cases. The ideal finish line was located at the crest of gingival tissue for 49% of respondents; 29% preferred 1 mm below the crest; and 22% preferred the finish line above the crest of tissue. Average chair time scheduled for a crown preparation appointment was 76 ± 21 minutes. Practice and dentist characteristics were significantly associated with margin choice including practice type (p < 0.001), region (p < 0.001), and years since graduation (p < 0.001). CONCLUSIONS Network dentists prefer chamfer/heavy chamfer margin designs, followed by shoulder preparations. These choices were related to practice and dentist characteristics.

Manufacturing of aerospace components consists of combination of different types of machining, finishing, and measuring processes. One of the finishing processes is deburring, i.e. a finishing process to remove burrs from work coupons after a boring hole process. Deburring is conducted to achieve required surface finish quality prior to further processes in assembly line. This paper introduces sensor data analysis as a tool to quantify and correlate the deburring stage with the features extracted from sensors data. This study covers signal processing, feature extraction and analytical method to determine its relevancy to the surface finish quality from deburring process. Wavelet decomposition and Welch’s spectrum estimate is used as a signal processing and feature extraction method. Consequently, the features are used as the basis for analysis by adaptive neuro-fuzzy inference system (ANFIS). The ANFIS yields the output corresponding to the predicted surface finish quality in terms of boss hole chamfer length and the stage classification of deburring process. The results show a decreasing trend in measured vibration signal, which is qualitatively well correlated to the deburring stage and the development of chamfer length during deburring process.

This letter proposes an effective method to improve object location in Chamfer template matching (CTM) based object detection using image segmentation. In our method, object bounding boxes are iteratively adjusted to fit with the object images obtained from image segmentation in a probabilistic model. The proposed method was tested with state-of-the-art CTM-based object detectors. Experimental results have shown the proposed method improved the location accuracy of the object detectors and reduce the false alarms rate.

Background/aims Fragment reattachment is a procedure that offers advantages, such as preservation of tooth structure and maintenance of color, shape, and translucency of the original tooth. The aim of this study was to analyze the reattachment techniques used to restore anterior teeth fractured by trauma. Materials and methods The PubMed, LILACS, Web of Science, Cochrane, and Scopus databases were searched in October 2016, and the search was updated in February 2017. A search of the gray literature was performed in Google Scholar and OpenGrey. Reference lists of eligible studies were evaluated to identify additional studies. Two authors assessed studies for inclusion and extracted the data. In vitro studies that evaluated permanent human teeth fractured by trauma were included. Results Twenty-one studies remained after screening. The bond strength between the fragment and the crown was evaluated in 119 experimental groups. Ten different techniques were evaluated as follows: no preparation, chamfer, bevel, anchors, overcontour, internal groove, no preparation associated with chamfer after reattachment, fragment dentin removal associated with chamfer after reattachment, bevel associated with overcontour, and groove associated with shoulder. Five different materials were used to reattach the fragment: bonding system, luting composite resin, flowable composite, microhybrid composite, and nanocomposite. Conclusion Fragment reattachment using a technique with no preparation and an adhesive system associated with an intermediate composite with good mechanical properties can restore part of the resistance of the fractured tooth.

With the advancement in construction and engineering techniques, a pragmatic shift in architectural designs of tall buildings can be observed. The buildings are going taller and unconventional shaped rather than traditional. Generally shape and orientation of the building are determined on the basis of architectural and practical considerations, but the wind-induced excitations encouraged by bluffness of the building shapes cannot be neglected also. To safeguard the functional requirement of tall flexible buildings and to mitigate the excitations, various methods are available. Among these methods, aerodynamic modification techniques are very potent, which affect the mechanism of vortex shedding phenomenon considerably and have got a lot of attention in recent years. Based on the impact of modification on the outer architecture of the building, the aerodynamic modifications are categorized in two groups i.e. minor modifications (corner cut, rounding, chamfer etc.) and major modifications (taper, set-back, twist etc.). The present study comprehensively reviews the recent/past aerodynamic modification techniques applied to high-rise buildings.

Statement of problem Because crowns with open margins are a well-known problem and can lead to complications, it is important to assess the accuracy of margins resulting from the use of a new technique. Currently, data regarding the marginal fit of computer-aided design and computer-aided manufacturing (CAD-CAM) technology to fabricate a complete gold crown (CGC) from a castable acrylate resin polymer block are lacking. Purpose The purpose of this in vitro study was to compare marginal discrepancy widths of CGCs fabricated by using either conventional hand waxing or acrylate resin polymer blocks generated by using CAD-CAM technology. Material and methods A plastic model of a first mandibular molar was prepared by using a 1-mm, rounded chamfer margin on the entire circumference of the tooth. The master die was duplicated 30 times, and 15 wax patterns were fabricated by using a manual waxing technique, and 15 were fabricated by using CAD-CAM technology. All patterns were invested and cast, and resulting CGCs were cemented on their respective die by using resin-modified glass ionomer cement. The specimens were then embedded in acrylic resin and sectioned buccolingually. The buccal and lingual marginal discrepancies of each sectioned portion were measured by using microscopy at ×50 magnification. Data were subjected to repeated measures 2-way ANOVA, by using the Tukey post hoc pairwise comparison test (α=.05). Results The factor of “technique” had no significant influence on marginal discrepancy measurement (P=.431), but a significant effect of “margin location” (P=.019) was noted. The confounding combination of factors was found to be significantly lower marginal discrepancy dimensions of the lingual margin discrepancy than on the buccal side by using CAD-CAM technology. Conclusions The marginal discrepancy of CAD-CAM acrylate resin crowns was not significantly different from those made with a conventional manual method; however, lingual margin discrepancies present from CAD-CAM–prepared crowns were significantly less than those measured on the respective buccal surface.

Along with the elevating number of cars, accidents due to car crashes are increasing. Therefore, technology is needed to reduce the occurrence of the drivers’ injuries. Crash box is one of the potential passive safety technology which is widely observed today. Crash box is installed between bumper and chassis, aims to reduce the cassualties when the car crashes. In this article, crash box research was conducted by real experimental method through quasi-static test to evaluate the energy absorption capability of circular-shaped multi-segment crash box. Crash box material was made from aluminum A6063. The connection on each segment is a chamfer with 45 o angle. The connections between segments 1 and 2 were varied with 3 connection models, those are 1/4, 1/3 and 1/2 of the total length, i.e.120 mm. The results of the study showed that, the highest energy absorption obtained from the crash box with connection of 1/2 and the energy absorption is 5249.726 J. Crash box type of 1/4 and 1/3 exhibit energy absorption of 3886.238 J and 3106.027 J respectively. Generally, the deformation pattern on the crash box is mixed-mode (axisymmetric-diamond).