Ultrasonic Compaction Research Articles

Comparative Analysis of Mechanical Characteristics: Ultrasonically Compacted vs. Conventionally Additive Manufactured Polymeric Samples

This scientific paper presents a comparative analysis of the mechanical characteristics of PLA samples fabricated through conventional AM methods and AM then ultrasonically compacted. The study aims to assess the potential advantages and limitations of ultrasonic compaction of PLA AM samples, as a reinforcing manufacturing technique. The methodology involves the fabrication of PLA samples using AM processes, then ultrasonically compact part of them to make a comparative study on their mechanical characteristics, including tensile strength. Additionally, the surface morphology and internal microstructure of the samples are analysed using microscopy techniques. The results of the study provide insights into the mechanical performance and structural integrity of the ultrasonically compacted samples compared to the conventionally PLA AM samples. The findings highlight any potential improvements or limitations in terms of mechanical properties, such as strength, durability, and overall performance.

Optimization of 3D Printing Parameters of High Viscosity PEEK/30GF Composites.

The aim of this study was to optimize a set of technological parameters (travel speed, extruder temperature, and extrusion rate) for 3D printing with a PEEK-based composite reinforced with 30 wt.% glass fibers (GFs). For this purpose, both Taguchi and finite element methods (FEM) were utilized. The artificial neural networks (ANNs) were implemented for computer simulation of full-scale experiments. Computed tomography of the additively manufactured (AM) samples showed that the optimal 3D printing parameters were the extruder temperature of 460 °C, the travel speed of 20 mm/min, and the extrusion rate of 4 rpm (the microextruder screw rotation speed). These values correlated well with those obtained by computer simulation using the ANNs. In such cases, the homogeneous micro- and macro-structures were formed with minimal sample distortions and porosity levels within 10 vol.% of both structures. The most likely reason for porosity was the expansion of the molten polymer when it had been squeezed out from the microextruder nozzle. It was concluded that the mechanical properties of such samples can be improved both by changing the 3D printing strategy to ensure the preferential orientation of GFs along the building direction and by reducing porosity via post-printing treatment or ultrasonic compaction.

Influence of overlap rate and ultrasonic compaction on mechanical performance for additive manufacturing of continuous carbon fiber reinforced polylactic acid composites

The additive manufacturing (AM) technology of continuous fiber reinforced thermoplastic composites (CFRTPCs) is gaining attention in the composites industry due to its excellent mechanical performance, potential designability and light-weight structures. Process parameters of AM have a significant impact on mechanical performance and forming accuracy. There is still a Lack of clear design basis for hatch spacing as structural parameter. This study focused on the effect of overlap rate on AM performance of continuous carbon fiber (CCF)/polylactic acid (PLA) composites through the mechanical test, surface morphology, defects characterization and failure analysis, and investigated the adaptability of ultrasonic compaction post-treatment to overlap rate settings. The results indicated that proper overlap state between filaments was beneficial for mechanical properties. The optimal interlaminar shear strength (ILSS) increased to 22.72 MPa by 56 % and tensile strength improved by 17.5 % to 721.65 MPa at various overlap rates. Surface roughness remained stable at approximately 33 μm. Ultrasonic compaction achieved a maximum ILSS up to 24.84 MPa with improvement of 10.26 %, and tensile strength reached to 736.76 MPa with 2.09 % improvement, showing excellent adaptability to overlap rate design. Research findings will improve understanding of digital adjustment mechanisms for printing parameters and provide design guidance for high-performance AM technology of CFRTPCs.

Methods Used for the Compaction and Molding of Ceramic Matrix Composites Reinforced with Carbon Nanotubes

Ceramic matrix composites reinforced with carbon nanotubes are becoming increasingly popular in industry due to their astonishing mechanical properties and taking into account the fact that advanced production technologies make carbon nanotubes increasingly affordable. In the present paper, the most convenient contemporary methods used for the compaction of molding masses composed of either technical ceramics or ceramic matrix composites reinforced with carbon nanotubes are surveyed. This stage that precedes debinding and sintering plays the key role in getting pore-free equal-density ceramics at the scale of mass production. The methods include: compaction in sealed and collector molds, cold isostatic and quasi-isostatic compaction; dynamic compaction methods, such as magnetic pulse, vibration, and ultrasonic compaction; extrusion, stamping, and injection; casting from aqueous and non-aqueous slips; tape and gel casting. Capabilities of mold-free approaches to produce precisely shaped ceramic bodies are also critically analyzed, including green ceramic machining and additive manufacturing technologies.

Densification Mechanism of Soft Magnetic Composites Using Ultrasonic Compaction for Motors in EV Platforms.

In this paper, the densification mechanism of ultrasonic compaction was analyzed using a force balance model. Ultrasonic compaction is quite a promising way to solve the lower mechanical property problem of green compact in the compaction process, although it has some obstacles to overcome for its various applications. Our model proposes that the resultant density is achieved as the applied and resistance forces reach the equilibrium state. Based on the proposed model, the ultrasonic compaction increases the density of green compact by reducing the internal friction between the powder and compaction die, as well as the internal friction among particles themselves. It was also found that during the powder compaction, the ultrasonic vibration mostly contributes to slipping and the rearrangement of the particles.

Ultrasonic compaction of granular geological materials

It has been shown that the compaction of granular materials for applications such as pharmaceutical tableting and plastic moulding can be enhanced by ultrasonic vibration of the compaction die. Ultrasonic vibrations can reduce the compaction pressure and increase particle fusion, leading to higher strength products. In this paper, the potential benefits of ultrasonics in the compaction of geological granular materials in downhole applications are explored, to gain insight into the effects of ultrasonic vibrations on compaction of different materials commonly encountered in sub-sea drilling. Ultrasonic vibrations are applied, using a resonant 20kHz compactor, to the compaction of loose sand and drill waste cuttings derived from oolitic limestone, clean quartz sandstone, and slate-phyllite. For each material, a higher strain for a given compaction pressure was achieved, with higher sample density compared to that in the case of an absence of ultrasonics. The relationships between the operational parameters of ultrasonic vibration amplitude and true strain rate are explored and shown to be dependent on the physical characteristics of the compacting materials.

A Comparative Evaluation of Apical Seal Associated with Ultrasonic Retrograde Cavities Filled with Bioactive Material (In Vitro Study)

Background: The aim of this study was to evaluate and compare the apical microleakage around retrograde cavities prepared with ultrasonic technique and filled with (Biodentine™) Materials and methods: 40 extracted single rooted human permanent maxillary teeth with mature apices were selected. The roots were prepared chemo-mechanically using k-files with crown-down technique and then obturated with lateral condensation gutta-percha technique. Teeth were divided into four main groups according to the cavity preparation method either manual or ultrasonic technique: Group A (n=10): A class I retrograde cavity at root end was prepared with traditional handpeice equipped and placement of Biodentine with manual condensation. Group B (n=10): A class I retrograde cavity at root end was prepared with Piezoelectric ultrasonic device equipped with ultrasonic tip with only manual compaction of the material. Group C (n=10): traditional handpeice and placement of Biodentine using both manual compaction and 5 second ultrasonic activation. Group D (n=10): Piezoelectric ultrasonic device and placement of Biodentine with both manual compaction and 5 second ultrasonic compaction. The teeth were immersed in 1% aqueous Methylene blue dye for 72 hr. Then they were sectioned longitudinally with a diamond disc and the depth of dye penetration was examined under high magnification 20X. Results: Statistical analysis showed a highly significant difference in microleakage among the tested groups in which Piezoelectric technique has proved superiority in retrograde cavity preparation and compaction of Biodentin when dye penetration scores were compared. So microleakage was highest with cavities prepared with handpeice and manual application of retrograde material group A (2.73±0.39) followed by microprepared cavities group C (1.86±0.16), and it was lowest with ultrasonically-prepared cavities group B (1.09±0.28) and group D (0.26±0.19). Conclusion: ultrasonic preparation produced significantly less microleakage than conventional method. Also less microleakage was observed with ultrasonic compaction of Biodentin when compared with conventional method of compaction.

Ultrasonic Joining of Multiple Core Conductors for Automotive Industry

The paper presents aspects regarding the development of innovative ultrasonic welding technologies at ISIM Timisoara and the advantages of using them in the automotive industry for making similar and dissimilar joints for non-ferrous materials. The experimental results through mechanical tests, microscopy, digital imaging, ultrasonic compacting and hybrid joining of samples Cu-Cu, Al-Al and Al-Cu, highlight the potential use of aluminium as a substitute for multiple core copper conductors in automotive industry.

Structural and Functional Characterization of Ultrasonic Joining for Multiwire Conductors for Automotive Industry

This paper presents the general aspects concerning the development of innovative ultrasonic welding technologies at ISIM Timisoara and the advantages of using ultrasonic metal joining, compared with conventional joining methods, in the automotive industry for joining multiwire connectors from copper and aluminium. The experimental results through mechanical testing, electrical conductivity, digital imaging microscopy, ultrasonic compacting, realized on Cu-Cu, Al-Al and Al-Cu samples, underscore the potential for using aluminum as a substitute for copper multiwire connectors in automotive industry.

Study of the ultrasonic compaction process of composite laminates—part II: advanced numerical simulation

The ultrasonic compaction might be a suitable technique to obtain well compacted composite laminates in order to implement them in out-of-autoclave automated curing processes. This procedure generates an ultrasonic vibration over the laminate that makes the resin heat and allows the composite plies to be compacted. The numerical study of this heat generation and its distribution within the laminate requires the modelling of the resin and the fibre layers separately, requiring a very fine mesh. Furthermore, the process needs a discretization along the time with very short time steps, in order to model the ultrasonic vibration properly. For these reasons, a fine FEM solution is very costly to compute. Space-time separated representations as the ones considered in Proper Generalized Decomposition (PGD) techniques seem to be an appealing choice for addressing the solution of ultrasonic compaction thermomechanical models. In this work, the formulation and implementation of a PGD solution of a model for the viscous heating and temperature distribution during the compaction of composite layers is presented. The compaction will be studied in two operating modes: it will be studied as a transient problem, assuming that the compactor is still over the laminate and as a steady-state problem, assuming that the compactor is moving along the laminate. Finally, the solution obtained with the transient model will be compared with experimental measurements, showing that the model predicts the behavior of the temperature inside the laminate properly.

Study of the ultrasonic compaction process of composite laminates - part I: process modeling

Recent advances in out-of-autoclave manufacturing processes for composite materials may require the compaction of the pre-preg plies just after placing them. Ultrasonic compactors are a good solution for this task. The quality of the compaction will depend on the frequency and amplitude of the ultrasonic vibration, which produces a viscous heating in the resin. The increase in temperature liquefies the resin, thus helping the air bubbles to escape. The study of how this heat is generated and distributed is fundamental to better understand and optimize the compaction process. In this work, the formulation of a thermomechanical model for the viscous heating of an uncured laminate of pre-preg plies due to ultrasonic vibrations is presented. In addition, a thermal model for the heat transfers to obtain the temperature distribution during the compaction process of composite layers will be shown.

A comparison of four gutta‐percha filling techniques in simulated C‐shaped canals

To compare four gutta-percha filling techniques in simulated C-shaped canals based on filling quality at three cross-sectional levels, filling time and the apical extrusion of gutta-percha. Forty resin simulated C-shaped canals were constructed and filled using one of four techniques: cold lateral compaction (LC), ultrasonic compaction (UC), single cone with injectable gutta-percha (Obtura II(™) ) (IT) and core-carrier (Thermafil(®) ) (CC). Cross sections were made at 1 (L1), 3 (L3) and 6 (L6) mm from the canal terminus. Areas of gutta-percha, sealer and voids in each cross section were measured using an image analysis system. Data were analysed using a univariate general linear model and post hoc test (Dunnett's T3). Data on time taken to fill canals was evaluated using the Bonferroni post hoc test. CC had more gutta-percha and less sealer compared with IT at L1 (P<0.05). LC had marginally significantly less gutta-percha than CC at this level (P=0.049). At level 3mm, significantly more gutta-percha and less sealer were present in IT compared with LC (P<0.05). The techniques showed no difference in quality at L6. The time for LC (20.72min) was three times longer than for both IT (6.11min) and CC (6.67min), whereas for UC (26.92min), it was four times longer (P<0.001). Finally, the four techniques were not different in the occurrence of apical extrusion of gutta-percha. The core-carrier technique was the most effective technique when assessed by gutta-percha area in this simulated C-shaped canal.

Development of a Technology for the Fabrication of Articles Made of Complex-Modified Polytetrafluoroethylene for Dry Friction Assemblies

The influence of the parameters of ultrasonic compaction on the mechanical and tribological properties of a composite polytetrafluoroethylene-based material is considered. It is shown that through the use of ultrasonic compaction in the course of fabricating complex-modified polytetrafluoroethylene, an increase in the ultimate strength, modulus of elasticity, and wear resistance of the composite are achieved together with a significant reduction in its friction coefficient. The new technology of ultrasonic compaction of a composite material may be used to fabricate plain bearings, sealing elements of shafts and axles of plants and mechanisms, as well as hydraulic engines, and the rods of hydraulic cylinders.

Design of Ultrasonic Compaction Tool for Powder Metallurgy

The current study is presented into the investigation of the application of ultrasonic vibration on the lower punch during compaction process of powder metallurgy material. The lower punch is specifically designed of ultrasonic horn which has been tuned at frequency of 20 kHz and vibrates in longitudinal mode. Finite Element modeling was used to assist the design process of the lower punch or horn. The horn was fabricated using high grade aluminium alloy and mounted onto the ultrasonic system test rig and subsequently tested prior the experimental process begins. Various static and ultrasonic compaction procedures have been carried out to confirm the capability of the tool to operate. The compaction force was reduced significantly at the onset of ultrasonic vibration applied compared to without ultrasonic.

Motor Core Fabrication through Ultrasonic Vibration Compaction of Soft Magnetic Composite

In this study, ultrasonic vibration compaction of a soft magnetic composite (SMC) has been investigated. The importance of the SMC application to the electromagnetic industry has been increasingly recognized because it has advantages of lower eddy current loss and motor design with a three-dimensional (3D) magnetic core. However, SMC's have not yet reached the stage of practical use because of their lower density than the density of conventional electrical steel sheets. To improve the density of the SMC and reduce the friction between die and powder during the compaction process an ultrasonic compaction method was used. The high-power ultrasonic vibration system of 2.5 kW with six transducers was designed to form a high-density SMC magnetic motor core effectively. To achieve the optimal compaction condition of the SMC, effects such as vibration amplitude, pressure, position of compaction, and ratio of diameter to height were also investigated. The results showed that the density of the SMC could be improved by about 7% under the determined optimal condition. Moreover, to verify the effectiveness of the proposed method, the fabricated SMC core was embedded into an electrical motor and a 5% improvement of motor performance was achieved.

The Effect of Ultrasonic Vibration on the Compaction Characteristics of Ibuprofen

ABSTRACTAn ultrasonic (US) compaction rig has been developed, capable of providing compaction pressure together with high-power ultrasonic vibrations of 20 kHz to a powder or granular material in a die. The rig has been used to investigate the effect of ultrasound on the compaction properties of ibuprofen, a drug with poor compaction properties which produces tablets that are weak and frequently exhibit capping. It was found that coherent ibuprofen tablets could be prepared by ultrasound-assisted compaction at pressures as low as 20–30 MPa. Application of ultrasound before and after compaction was found not to be as effective as ultrasound applied during compaction. The breaking forces of the tablets produced with ultrasound applied during compaction were found to be consistently significantly higher than when compaction was performed conventionally, or with ultrasound applied before or after compaction. Application of ultrasound during compaction made it possible to increase tablet mechanical strength, typically by a factor of 2–5. It was concluded that pressure should be applied together with ultrasound in order to achieve a better acoustical contact, which is required to transmit vibrations from the horn to the material, and also to bond the surfaces of the particles.Ultrasound application during ibuprofen compaction also resulted in an increase in the apparent density, in relation to the apparent density of conventionally prepared tablets, of up to 14.4%. Ultrasound appears to improve particle rearrangement and provides energy for partial melting of particle asperities and subsequent fusion of particle surfaces, so as to increase interparticulate bonding. Solid bridge formation was thought to result in a reduction of void space, which in turn reduced the rate of water penetration into the compacts and consequently increased disintegration and dissolution times.It was found that the results of ultrasound-assisted compaction are influenced by formulation and US time. When ibuprofen was mixed with a second material, such as dibasic calcium phosphate dihydrate (DCP) or microcrystalline cellulose (MCC), stronger tablets were prepared by ultrasound-assisted compaction compared to the compacts containing no filler. Positive interactions were considered to have occurred due to ultrasound-induced bonding between the two materials. With an increase in DCP and MCC concentration in ibuprofen formulations, disintegration and drug dissolution rates of the tablets produced with ultrasound significantly increased.Using temperature-sensitive labels it was found that thermal changes occurred in powdered solids undergoing ultrasound-assisted compaction. Increases in the temperature of tablets were related to US amplitude and US time. With an increase in US amplitude from 5 to 13 µm, the temperature of the DCP tablet surface increased from 40 to 99°C. With an increase in US time from 1 to 5 sec, the temperature of the surface of ibuprofen tablets increased from 43 to 60°C. Increased tablet temperature was thought to be due to ultrasonic energy dissipation turned into heat.X-ray powder diffraction (XRD) studies of ibuprofen tablets prepared by ultrasound-assisted compaction at 32 MPa revealed that no changes in chemical or/and crystalline structure of the material occurred when ultrasound was applied for up to 5 sec (US amplitude 7 µm). An XRD study of DCP tablets produced by ultrasound-assisted compaction at 32 MPa with ultrasound of different amplitudes (5, 7, 13 µm) applied for 2 sec indicated that no material deterioration occurred in all the tested samples.

The Effect of Ultrasonic Vibration on the Compaction Characteristics of Paracetamol

An ultrasonic (US) compaction rig has been developed that is capable of providing compaction pressure together with high‐power ultrasonic vibrations of 20 kHz to a powder or granular material in a die. The rig has been used to investigate the effect of US on the compaction properties of paracetamol, a drug that produces tablets that are weak and frequently exhibit capping. It was found that coherent paracetamol tablets could be prepared by US‐assisted compaction at pressures as low as 20 to 30 MPa. Application of US before and after compaction was not found to be as effective as US applied during compaction. The breaking forces of the tablets produced with US applied during compaction were found to be consistently significantly higher than when compaction was performed conventionally or with US applied before or after compaction. The application of US during compaction made it possible to increase tablet breaking force, typically by a factor of 2 to 5. It was concluded that pressure should be applied together with US to achieve a better acoustical contact, which is required to transmit vibrations from the horn to the material and also to bond the surfaces of the particles.US application during compaction also resulted in an increase in apparent density, in relation to the apparent density of conventionally prepared paracetamol tablets, of up to 12.8%. US appears to improve particle rearrangement and provide energy for partial melting of particle asperities and subsequent fusion of particle surfaces, thus increasing interparticulate bonding. Development of solid bridges between the particles during US‐assisted compaction was observed on scanning electron photomicrographs. Solid bridge formation was thought to result in a reduction of void space, which in turn reduced the rate of water penetration into the compacts and consequently increased tablet disintegration and drug dissolution times.It was found that the results of US‐assisted compaction are influenced by formulation and US time. An increase in binder (polyvinylpyrrolidone) concentration and/or US time resulted in a significant increase in the breaking forces of paracetamol tablets produced with US. When paracetamol was mixed with a second material, such as dicalcium phosphate dihydrate and microcrystalline cellulose, stronger compacts were prepared by US‐assisted compaction compared with the tablets containing no filler. Positive interactions were considered to have occurred as a result of US‐induced bonding between the two materials.Overall, the application of US was found to significantly improve the compaction properties of paracetamol. © 2000 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 89:705–723, 2000

Ultrasonic compacting of zirconium ceramics from ultradispersed powders

A method for compacting ultradisperse powders (UDP) of ZrO2-3% Y2O3 by radially transmitted ultrasonic vibrations (USV) by imposing static pressing pressure is developed. The optimized USV regimes provide compacts from UDP with optimum properties.

Manufacture strengthening of corundum-zirconium ceramic in ultrasonic compacting of ultradisperse powders

The effect of ultrasonic compacting (USC) of ultradisperse oxide powders of the ZrO2-Al2O3 system on sintering of the ceramic was analyzed. It was shown that USC increases the density of pressed samples to 55% of the theoretical density of the ceramic. The sintering temperature of the corundum-zirconium ceramic was reduced by 200–300°C with the USC method. The ceramic obtained had improved strength properties.

Strain distributions in vibrating rods of variable cross-sections—Part 1: Experiment and finite element calculations

The role of the finite element method in studying stress/strain/displacement distributions in vibrating structures is discussed with respect to high-power ultrasonic compacting and fatigue testing. The principles of the formulations used to perform the numerical simulations are briefly mentioned. The computed results are compared with those of laboratory experiments in which plates of different geometries were excited to longitudinal vibrations. Taking a rectangular specimen into account allowed additional comparison with an analytical solution of the problem. Thus it was possible to test the reliability and usefulness of the various methods.