Vibratory Methods Research Articles

ABRASIVE SURFACE TREATMENT OF ALSI10MG PARTS MADE BY L-PBF

The scientific community has been intensively studying how to improve the level of surface roughness on 3D-printed parts, particularly metallic parts made using the selective laser melting (SLM) technique. Various research papers on this subject have revealed that accurate surface roughness data can be generated using several methods that are, in fact, not cost-effective. For this reason, the finishing processes are an integral part of the overall production, especially for those components where the primary concern is not only appearance but also functional properties (e.g., lower friction, reduced noise, etc.). This work deals with the measurement of the surface roughness of tumbled parts produced with SLM after surface treatment with centrifugal and vibratory methods. Tumbling was performed with ceramic, plastic, and porcelain mediums. At the end, there is an evaluation of the measurement data based on the required surface roughness of the components.

Laboratory investigation of gyratory-vibratory compaction method for better simulating asphalt mixture field compaction

To better simulate the effect of vibration and kneading for steel-wheel roller, a novel lab compaction method combining the effect of vibratory and gyratory compaction was proposed. X-ray tomography was used to compare the air void distribution of the in-situ core samples and the laboratory-compacted samples by different compaction methods, including vibratory, gyratory and the combinatory method. It was found that different compaction methods significantly affected the air void distribution of specimens. The combination of vibratory and gyratory compaction methods presented comparable air void distribution and compaction effect to the in-situ core samples.

Comparative Evaluation of Vibratory Physiotherapy Methods in the Early Period after Cardiac Surgery

Postoperative respiratory complications in patients undergoing cardiac surgery occur in 20‒30% cases, and the most of them can be associated with ineffective cough and bronchial mucus evacuation.The objective. Comparative assessment of effectiveness and safety of methods for stimulating the evacuation of bronchial secretions using oscillatory PEP-therapy (Acapella Duet), oscillatory chest compression insufflator-aspirator “Comfort Cough Plus”, and the traditional method of manual chest percussion in the early period after cardiac surgery.Subjects and Methods. The prospective study included 120 cardiac surgery patients. They were divided into 3 groups (40 in each), depending on the type of the applied respiratory procedure. Distribution into groups was carried out by random selection. All procedures were performed 10‒12 hours after tracheal extubation. Before the procedure and 20 minutes after it, the efficiency of sputum discharge was assessed, gas exchange indices on room air breathing and maximum inspiratory lung capacity (MILC) were measured.Results. Ineffective bronchial mucus evacuating in the early period after tracheal extubation was observed in 86.7% of the patients. A single procedure of both PEP-therapy (Group 1) and mechanical cough stimulation (Group 2) led to improved sputum passage, as evidenced by an increase in the number of patients with productive cough by 4.25 times (p < 0.0009) and 5.3 times (p < 0.0007), respectively. In patients of Groups 1 and 2, an increase in MILC was observed (by 42.2% and 60.0%, respectively, p = 0.000001), the difference between the groups was statistically significant. In Control Group 3, with manual physiotherapy, the average increase in MILC was only 11.6%. Mechanical respiratory therapy procedures led to significant improvement in gas exchange variables, as evidenced by an increase in SpO2 in Groups 1 and 2 (p = 0.000009 and 0.000001, respectively) and a decrease in the proportion of patients with impaired oxygenating lung function (SpO2 below 92%) by 11 and 12 times, respectively (p < 0.01). The most significant changes were revealed in case of mechanical stimulation with aspirator-insufflator due to combination of two methods (oscillatory chest compression and lung inflation). In Control Group, no significant changes of gas exchange variables were observed.Conclusion: Mechanical vibratory methods for stimulating the bronchial secretion evacuation have significant advantages over classical manual chest massage in patients after cardiac surgery. Their positive effect on sputum passage, ventilatory parameters and gas exchange was noted, and the most pronounced effect was observed after oscillatory chest compression with insufflator-aspirator. The procedures were well tolerated and there were no complications associated with them.

Life Cycle Sustainability Assessment of Geotechnical Ground Improvement Methods

A life-cycle sustainability assessment evaluated and compared the impacts of five ground improvement methods commonly implemented to mitigate liquefaction: compaction grouting, deep dynamic compaction, deep soil mixing, vibro compaction, and vibro replacement (i.e., stone columns). Using typical scopes of work provided by geotechnical contractors who specialize in ground improvement, this study developed sustainability benchmarks for the life-cycle impacts and costs of each method, quantified the consequences of the risk and uncertainty inherent in ground improvement projects, and examined impacts to land and soil resources that occur throughout the life cycle. Results showed that deep soil mixing and compaction grouting are the most impactful and costly methods due to the use of portland cement, an energy- and emissions-intensive material. Vibratory methods and deep dynamic compaction are more sustainable, despite the fact that their impacts and costs are more variable and uncertain. Although many factors influence ground improvement design selection (e.g., safety, performance criteria, feasibility, and cost), the results of this study may help inform decision making to realize more sustainable infrastructure.

Vibratory driving of piles and sheet piles – state of practice

The installation of piles by vibratory methods is discussed and illustrated by case histories. The influence of vibration frequency – which can be controlled during vibratory driving but not during impact driving – on pile penetration, bearing capacity and emission of vibration is examined. The driving process affects the performance of vibratory-driven piles more strongly than impact-driven piles. Concepts are presented for assessing driveability. The importance of resonance of the vibrator–pile–soil system (system resonance) for driveability and pile bearing capacity is explained. Ground vibrations measured on and below the ground surface show that strong oscillating horizontal stresses are generated. These stresses can temporarily reduce the shaft resistance during driving, which can explain why vibratory driving is effective even in dense granular soils. Model tests show that, in granular soils, the bearing capacity of piles vibrated after driving at system resonance is significantly higher than that of piles installed only at high frequency. A concept is described suggesting that, during vibratory driving at high frequency, a zone is created adjacent to the pile shaft where the normal effective stress acting against the pile shaft is reduced due to arching. This arching effect can explain the reduced shaft resistance of piles installed at high frequency.

Hardening of the working bodies of agricultural machines by electric spark and vibratory arc processing

The paper presents the results of studies of some physical and mechanical properties of metal samples made of 65G steel, hardened by electric spark and vibratory arc methods. Research is related to solving the problems of increasing the working resource of the working bodies of agricultural machines. The studied elemental composition, phase composition, and microstructure of the surface of the samples.

Energy consumption in the manufacture of metal powders by vibratory disintegration methods

The results obtained in comparative vibratory disintegration studies of alloy metal chips are presented. The specific performance and energy consumption indicators are established. The paper assesses the influence of the level of vibration exposure on the material crushed in a KID vibratory crusher and on the efficiency of its subsequent grinding in a vibrating mill.

Horizontal stress increase induced by deep vibratory compaction

Compaction by vertically or horizontal oscillating probes increases not only the soil stiffness but also the horizontal effective stress. An important, but often neglected, consequence is that compaction also causes preloading of the soil. The change in horizontal stress following vibratory compaction can be measured independently by two in situ methods – a cone penetration test (CPT) and a flat dilatometer test (DMT). Values of sleeve resistance (CPT) and horizontal stress index (DMT) can be determined prior and after compaction. In this work, five case histories reported in the literature where different vibratory compaction methods were used (dynamic compaction, vibroflotation, VibroWing, TriStar and resonance compaction) were re-analysed. For each test site, the change in CPT cone resistance and sleeve resistance was determined and compared with the increase in horizontal stress index from DMTs. The preloading effect due to vibratory compaction was estimated using empirical correlations.

Blast-induced liquefaction in silty sands for full-scale testing of ground improvement methods: Insights from a multidisciplinary study

In the engineering geology field increased attention has been posed in recent years to potential liquefaction mitigation interventions in susceptible sand formations. In silty sands this is a major challenge because, as the fines content increases, vibratory methods for densification become progressively less effective. An alternative mitigation technique can be the installation of Rammed Aggregate Pier® (RAP) columns that can increase the resistance of the soil, accounting for its lateral stress increase and for the stiffness increase from soil and RAP composite response. To investigate the influence of these factors on liquefaction resistance, full-scale blast tests were performed at a silty sand site in Bondeno (Ferrara, Italy) where liquefaction was observed after the 2012 Emilia-Romagna earthquake. A multidisciplinary team of forty researchers carried out devoted experimental activities aimed at better understanding the liquefaction process at the field scale and the effectiveness of the treatment using inter-related methods. Both natural and improved areas were investigated by in-situ tests and later subjected to controlled blasting. The blast tests were monitored with geotechnical and geophysical instrumentation, topographical surveying and geological analyses on the sand boils. Results showed the RAP effectiveness due to the improvement of soil properties within the liquefiable layer and a consequent reduction of the blast-induced liquefaction settlements, likely due to soil densification and increased lateral stress. The applied multidisciplinary approach adopted for the study allowed better understanding of the mechanism involved in the liquefaction mitigation intervention and provided a better overall evaluation of mitigation effectiveness.

Towards automated and painless venipuncture – vibratory needle insertion techniques

Abstract The insertion of a needle into soft inhomogeneous tissue is required for many medical procedures. It has been shown that vibratory needle insertion methods have the ability to reduce insertion forces, which are correlated with increased needle placement precision, and reduced frequency and intensity of pain and trauma felt. This paper reviews different vibratory needle insertion methods that have been studied experimentally, addressing vibration generation, vibration frequency and amplitude, and force measurement. Reductions of up to 73 % in peak insertion force (150 Hz), and 37 % in placement error (15 Hz) were reported. Additionally, ultrasonic vibration (84 kHz) reduced the force by up to 28 %. The results of vibratory insertion show promise, specifically in regard to automated needle devices.

Performance Evaluation of Recycled Asphalt Pavement Materials and Cold Recycling Mixtures Designed with Vibratory Compaction Method

In this paper, the basic composition and performance evaluation of the recycled asphalt pavement (RAP) materials were firstly analyzed, and two methods were proposed to evaluate strength characteristics of RAP materials, including a triaxial method for the residual strength and the mortar cementing method for the strength of RAP lump. Then, the cold recycling technology was applied on RAP materials with emulsified asphalt by using vibratory compaction and heavy-duty compaction methods (Proctor compaction method), and the results showed that the maximum dry density obtained by heavy-duty compaction was closer to the actual situation. Finally, the effects of wetting water, emulsified asphalt dosage and curing conditions on the performance of the specimens were investigated. It was found that when the emulsified asphalt was mixed uniformly, whether or not to add the wetting water have almost no effect on the strength of the molded specimens. When the matrix asphalt content of the emulsified asphalt was 30%~60%, the water could be directly added to the cold recycling mixture. The intensity of accelerated curing for two days at 40 °C was approximately equal to that of natural curing for three days, while that of accelerated curing for three days at 40 °C was approximately equal to that of natural curing for seven days, which provided a basis for the short-term laboratory test.

Mechanical Properties of Steel Fiber-Reinforced Concrete by Vibratory Mixing Technology

As a kind of important engineering material, steel fiber-reinforced concrete was used widely in civil engineering. Up to now, steel fiber-reinforced concrete was usually produced by the traditional mixing method. For the reason of uniform distribution of fiber, the reinforcement of mechanical properties of concrete was inadequately performed. In this paper, C50 steel fiber-reinforced concrete and C60 steel fiber-reinforced concrete were manufactured by traditional mixing and vibratory mixing methods, respectively, and then, the cube compression test, flexural test, splitting tensile test, and the bending test were carried out. The reinforcement effects of mechanical properties were analyzed by comparing the traditional mixing and vibratory mixing methods. The results show that vibratory mixing can effectively improve the distribution of steel fibers in concrete and can increase the density of steel fiber concrete, and therefore, it effectively improves the mechanical properties of steel fiber-reinforced concrete when compared to the traditional mixing method.

Analysis and comparison of focused ion beam milling and vibratory polishing sample surface preparation methods for porosity study of U-Mo plate fuel for research and test reactors

Uranium-Molybdenum (U-Mo) low enriched uranium (LEU) fuels are a promising candidate for the replacement of high enriched uranium (HEU) fuels currently in use in a high power research and test reactors around the world. Contemporary U-Mo fuel sample preparation uses focused ion beam (FIB) methods for analysis of fission gas porosity. However, FIB possess several drawbacks, including reduced area of analysis, curtaining effects, and increased FIB operation time and cost. Vibratory polishing is a well understood method for preparing large sample surfaces with very high surface quality. In this research, fission gas porosity image analysis results are compared between samples prepared using vibratory polishing and FIB milling to assess the effectiveness of vibratory polishing for irradiated fuel sample preparation. Scanning electron microscopy (SEM) imaging was performed on sections of irradiated U-Mo fuel plates and the micrographs were analyzed using a fission gas pore identification and measurement script written in MatLab. Results showed that the vibratory polishing method is preferentially removing material around the edges of the pores, causing the pores to become larger and more rounded, leading to overestimation of the fission gas porosity size. Whereas, FIB preparation tends to underestimate due to poor micrograph quality and surface damage leading to inaccurate segmentations. Despite the aforementioned drawbacks, vibratory polishing remains a valid method for porosity analysis sample preparation, however, improvements should be made to reduce the preferential removal of material surrounding pores in order to minimize the error in the porosity measurements.

Thermal and vibration induced rotor blade deicing using carbon nanotube thermophones

The accumulation of ice on helicopter blades imposes limitations on the design and operation of rotorcrafts due to the large power requirement of thermal heating mats. Carbon nanotube (CNT) loudspeakers present a lightweight and efficient solution to this issue, utilizing both thermal and vibratory methods to remove ice and prevent it from forming. To evaluate the deicing capabilities of CNT, an enclosure was created to encapsulate the loudspeaker between two thin layers of aluminum to simulate the rotor blade surface. The speaker was then operated at a range of amplitudes and frequencies in simulated cold weather conditions. Preliminary tests show promising results, with surface temperatures exceeding 120°C in under four minutes when operated in a −20°C environment and surface excitation resultant from the ultrasonic vibration. Although further testing is needed, CNT loudspeakers show great promise in becoming a lightweight and efficient solution to the issue of ice accumulation on the surface of rotor b...

Book review

Ground Improvement by Deep Vibratory Methods (Second Edition)

Preparation of Uniform Sand Specimens Using Stationary Pluviation and Vibratory Methods

Relative density is an important state parameter that influences the soil behavior. Preparation of sand specimens with uniform density is critical during large-scale laboratory testing in geotechnical engineering. In this study, the details of a stationary air pluviation device used to prepare uniform sand specimens in a large-size test chamber with dimensions equal to 900 mm × 900 mm × 1000 mm (in length, width, and depth) are provided. The proposed device is found to be simple to construct due to presence of only two diffuser sieves with an ability to produce uniform sand beds in a reasonably quick time. Prior to construction of full-scale pluviation device, a scaled-down model of the device with plan dimensions equal to 300 mm × 300 mm is fabricated to perform calibration studies. The range of densities of two gradations of Indian Standard sand (IS Grade II and IS Grade III) obtained using this device for various heights of fall of sand particles and passing through different opening sizes are provided. Relative density in the range of 53–99 % and 74–99 % is achieved for IS Grade II and III sands, respectively. The spatial uniformity in densities is also assessed, and the coefficient of variation (COV) in the density is found to be less than about 7 %. In addition to pluviation method, uniform sand beds are also prepared using pneumatically-operated vibratory method. The target relative density of sand bed is achieved by adjusting the pressure of compressed air inside the vibrator, and the maximum relative density of IS Grade II and Grade III sands from vibratory method is found to be higher than that from pluviation method for the range of pressures chosen in the study.

A History of Deep Vibratory Methods for Ground Improvement: A Cost-Effective Foundation Solution for 80+ Years

Deep vibratory ground improvement methods, collectively referred to as vibro systems, have been utilized by the construction community in one form or another for the past 80 years. Development of the equipment, techniques, and applications have evolved and become a cost-effective ground improvement technology.

Analysis of the Vibrational Stress Relief for Reducing the Residual Stresses Caused by Machining

This research examines the use of vibratory methods to reduce residual stresses in structures. The main objective of this work is to seek a better knowing of the mechanism of the reduction of residual stresses of materials undergoing cyclic loading. Experiments have demonstrated that residual stresses can be largely relieved through vibratory stress relief (VSR) treatment. The factors that influence the reduction of residual stresses need to be understood to effectively apply the process. A mathematical model based on plasticity theorem with linear kinematic hardening is generated to explain the mechanism of reduction of residual stresses of materials experiencing cyclic loading. The numerical results from the mathematical model and the analytical results with existing experimental data for rectangular cross-section beams showed a similar trend.

Research on Vibration Properties of Copper-Titanium Alloys

The article addresses a method proposed for comprehensive research of vibration properties dedicated to new structural materials. The method in question comprises three-stage studies, thus enabling the related costs to be reduced on each stage of the process. Subjects of identification and assessment are both the properties and the material structure as well as numerically determined dynamic characteristics and actual vibration characteristics of materials. The article provides preliminary research results obtained for Cu-2Ti-1Co and Cu-6Ti-1Co alloys, the mechanical properties of which are very prospective. An additional advantage of the method proposed is the capability of identifying alloy types by application of non-destructive vibratory methods.

Standardless EDXRF Analysis Methods of U and Th in Malaysian Tin Slag Waste

Accurate quantification of uranium and thorium elements was performed in the absence of standards for the XRF analysis. This quantification method uses standard addition method. The standard addition method was first established by performing a micofocus XRF onto a sample. In the calibration graphs of uranium, the R2 was 0.9997 white the R2 value for thorium was 0.9915. Once the baseline quantity of both uranium and thorium were obtained, they were used to normalize all the quantification of other samples prepared by grab and vibratory methods. It was found out that the vibratory method gives more accurate results.