Shock Wave Technique Research Articles

Principles for designing sustainable and high-strain rate stress wave dissipating materials.

Dynamic covalent networks serve as effective tools for dissipating high-strain rate mechanical energy throughout reversible bond exchange reactions. Despite their potential, a gap exists in understanding how polymer chain mobility and the kinetics of bond exchange reactions impact the energy dissipating capabilities of dynamic covalent networks. This study presents an optimal strategy to enhance energy dissipation by controlling the side chain structures and bond exchange rates of dynamic covalent networks. Lipoic acid-derived polymers are chosen as our model system due to their easily tunable side chains and disulfide-rich backbones. High-strain rate stress waves are subjected to the polymers using a laser-induced shock wave technique. A strong correlation is observed between the energy dissipation capability and the glass transition temperature of the poly(disulfide)s. Furthermore, the addition of a catalyst to accelerate the disulfide exchange reaction improves energy dissipation. Leveraging the inherent nature of cyclic disulfides, our polymers exhibit self-healing and chemical recycling to monomers. The principles observed in this study provide a rational framework for designing sustainable and efficient energy dissipating materials.

Lamb waves evaluation in CFRP plates with laser shock wave technique

Lamb waves, which are guided waves propagating along the surface of a thin plate structure, have been investigated to remotely perform nondestructive testing for aircraft or infrastructures made of carbon fiber reinforced plastic (CFRP) plates. CFRP plates are prone to internal damage such as delamination, which does not occur in metallic materials. Although nondestructive methods such as X-ray, flash thermography, etc. have been investigated in several studies, they may have some disadvantages such as risks of radiation exposure or limitation in terms of size of the structures to be tested for the former, and heat diffusion for the latter. Laser thermoelasticity can generate Lamb waves remotely and nondestructively. However, the generated Lamb waves have a small amplitude; therefore, hundreds of measurements must be averaged to achieve a sufficient signal-to-noise ratio. For these reasons, it has not yet been demonstrated as possible to detect damage in large CFRP structures within a short time using nondestructive, remote-controlled methods. As a first step towards performing nondestructive tests in CFRP plates, this paper demonstrates the generation of A0 mode Lamb waves in the experimental plate samples using laser-induced plasma (LIP) shock waves. The validity of the proposed system is verified by comparing the phase velocities of Lamb waves in the CFRP plates with three different layups obtained with the proposed system, with the theoretical values obtained analytically. This system can generate vibrations in CFRP plates in frequency ranges of a few hundred kHz and allow to determine the phase velocity of the experimental Lamb waves up to approximately 100 kHz.

Effects of controllable shock wave on particle size characteristics of tin polymetallic ore crushing products

Different minerals in tin polymetallic ores have varying degrees of grindability. When the particle size distribution of the crushed ore is unreasonable, sufficient liberation of useful minerals necessitates an increase in the grinding time, resulting in the easily grindable tin metal minerals being over-ground, further causing the loss of tin metal resources in the subsequent beneficiation process. In this study, a controlled shock wave technique based on electrical pulses was introduced to pretreated tin polymetallic ores. The effects on the physical properties of the tin polymetallic ore obtained using controllable shock wave pretreatment were investigated using an ultra-depth three-dimensional microscope, a universal mechanical testing machine, mercury porosimeter, and crushing tests. The crushing results showed that the average particle size of the pretreated ore crushing products was 17.98% smaller than that of the untreated ore crushing products. Furthermore, the particle size characteristic equation demonstrated that the particle size distribution of the pretreated ore crushing products was more reasonable. The mechanism analysis revealed that the internal structure and surface morphology of the tin polymetallic ore were fractured by the controllable shock wave based on the electrical pulse, the compressive strength of the ore after pretreatment was reduced by 91.23%, and the porosity value was increased by 5.38% compared with that of the untreated ore. Therefore, it is feasible to pretreat tin polymetallic ores with controllable shock wave before the crushing process, which reduces the ore crushing resistance and improves the particle size characteristics of ore crushing products.

Determining the driving radiation flux on capsule in Hohlraum for indirect drive inertial confinement fusion

In 2021, the fusion yield of 1.35 MJ was produced at NIF by using indirect drive inertial confinement fusion (ICF), indicating that indirect drive ICF has reached ignition. However, the driving radiation flux on capsule inside Hohlraums is still a puzzle in indirect drive ICF studies. The energy deficit at NIF is still neither well understood nor solved. In this paper, we proposed a scheme to determine the driving radiation flux on the capsule by using the combination of the shock wave technique and the reemitted radiation flux measurement. In this scheme, a witness sample is placed in the Hohlraum center as the surrogate of the capsule. The shock velocity in the witness sample is measured by a streaked optical pyrometer from one side, and the temporal reemitted radiation flux is measured by a space-resolved flat response x-ray detector. Then, the peak of the radiation flux is determined by the shock velocity, and the time behavior of the radiation flux is determined by the reemitted flux through the numerical simulation of radiation hydrodynamic code. The rules for designing the witness sample and an example of applying this scheme to determine the driving radiation flux on capsule inside the octahedral spherical Hohlraum are presented in detail.

Immediate effect of shock wave versus muscle energy technique in cases of quadratus lumborum myofascial pain

Objective. To compare the effects of applying Extra-Corporal Shockwave treatment (ESWT) and Muscle Energy Technique (MET) to the Quadratus lumborum (QL) with regards to pain and function. Methods. 77 participants were included in this study. Patients were included if they were diagnosed as Myofascial pain syndrome, pain localized on the QL muscle; surrounding tightness; QL tenderness; and painful trigger points, causing referred pain around the QL. Outcome measures. Pain was measured by the Visual analogue scale (VAS), Pain pressure threshold (PPT) by the algometer and functional disability by the Oswestry pain disability index (ODI). Intervention. Patients were randomly divided into two groups. For the first group, ESWT was delivered by the Dornier AR2; smart focus technology on the tender point of the QL muscle. Three sessions were delivered with 2 days of rest following each session. The second group received the MET for 3 sessions as well. Results. The pre-treatment assessment revealed no significant differences between groups with regards to the pain (measured by the VAS & PPT) and Functional disability (measured by ODI). Following treatment, within group comparisons for the ECSW and Met groups respectively revealed significant differences with regards to pain (P = 0.0001), PPT (P = 0.0001) and ODI (P = 0.024 and 0.004 respectively) Between group comparisons revealed significant differences in favor of the ECSW group with regards to pain and PPT (P = 0.0001) with no significant difference with regards to ODI. Conclusion. ESWT showed better outcomes in improving QL myofascial pain and PPT than MET in the short term. Both treatment techniques improved the functional disability but with no significant difference between them.

Study of the radiation temperature on ablator by using the shock wave technique

A new diagnostic platform for more accurate diagnosis of the peak radiation temperature on ablator has been proposed. A nearly constant radiation temperature was obtained by two laser entrance holes spherical hohlraum. The peak radiation temperature on ablator was determined by the shock wave technique. A high-quality burn-through image of a two-step-shaped Au ablator was obtained in the experiment. The simulated mass ablation rate agrees well with the experimental result, while the peak radiation temperature measured by flat-response x-ray detectors outside the hohlraum was of ∼20 eV’s lower than that obtained by the shock wave technique. This deviation results in ∼20%’s decrease in the mass ablation rate in the simulation. Thus, the new diagnostic platform can provide more accurate peak radiation temperature diagnosis. This can greatly support the inertial confinement fusion ignition target design.

Soft Mango Firmness Assessment Based on Rayleigh Waves Generated by a Laser-Induced Plasma Shock Wave Technique.

Many methods based on acoustic vibration characteristics have been studied to indirectly assess fruit ripeness via fruit firmness. Among these, the frequency of the 0S2 vibration mode measured on the equator has been examined, but soft-flesh fruit do not show the 0S2 vibration mode. In this study, a Rayleigh wave is generated on a soft mango fruit using the impulse excitation force generated by a laser-induced plasma shock wave technique. Then, the flesh firmness of mangoes is assessed in a non-contact and non-destructive manner by observing the Rayleigh wave propagation velocity because it is correlated with the firmness (shear elasticity), density, and Poisson’s ratio of an object. If the changes in the density and Poisson’s ratio are small enough to be ignored during storage, then the Rayleigh wave propagation velocity is strongly correlated to fruit firmness. Here, we measure the Rayleigh wave propagation velocity and investigate the effect of storage time. Specifically, we investigate the changes in firmness caused by ripening. The Rayleigh wave propagation velocity on the equator of Kent mangoes tended to decrease by over 4% in 96 h. The Rayleigh wave measured on two different lines propagated independent distance and showed a different change rate of propagation velocity during 96-h storage. Furthermore, we consider the reliability of our method by investigating the interaction of a mango seed on the Rayleigh wave propagation velocity.

Direct Observation of Initial Stages of Precipitation Hardening Process in Commercial Al 6061 Alloy

Evolution of precipitates in aluminum 6061 alloy, quenched after 2 h hold at 550oC (super-saturated solid solution state – SSSS) and aged at 145oC (for up to 960 min), was studied by routine, ex-situ, transmission electron microscopy (TEM). In parallel, initial stages of the precipitation hardening process (after few-minute ageing) were studied by in-situ TEM. It was An appearance of short-living (~8 min) loose, disordered, spherical ~6 nm in diameter precipitates was captured. These precipitates rearranged after relatively long interval of time (~100 min, corresponding to 240 min ageing in the ex-situ tests) into long-range ordered rod-like Guinier–Preston (GP) zones (presuming GPI). The dimensions of the latter, 20 nm×2.1 nm, was determined based on the ex-situ TEM images.-Longer, 960 min, ageing results in GPI → GPII transformation accompanied by an increase of dimensions and strength of the rod-like precipitates. Determined geometrical parameters are in a reasonable agreement with corresponding parameters assessed previously using shock-wave technique. This fact implies that shock-wave technique can be considered as a useful tool for studying dislocation/defect interactions in a wide variety of strengthened alloys.

Shock wave determination of the strengthening of commercial aluminum alloy 6061 by point defects

The strengthening of aluminum alloy 6061 (AA6061) by different point defects was determined experimentally using a shock wave technique. Decay of the amplitude of elastic precursor wave τel with propagation distance h was studied in four groups of AA6061 samples, namely, that in the super-saturated solid solution state (SSSS), and those strengthened by atomic clusters (short-range order), by Guinier-Preston zones I and by Guinier-Preston zones II after, respectively 7.5, 240 and 960 min aging of the SSSS samples at 145 °C. The dependences τel(h) were found to be kinked at stress τ*, corresponding to the transition of the control of dislocation motion from phonon viscous drag at τel>τ* to thermally activated obstacle passage at τel<τ*. The values of strengthening by atomic clusters, GP-I, and GP-II zones were found equal to τsro=67, τGP-I=67, and τGP-II=124MPa, respectively. Activation volumes corresponding to the interaction of dislocations with the studied defects, estimated based on τel<τ* segments of the measured dependences τel(h), were found to be in reasonable agreement with existing concepts of dislocation/defect interactions.

First Octahedral Spherical Hohlraum Energetics Experiment at the SGIII Laser Facility.

The first octahedral spherical hohlraum energetics experiment is accomplished at the SGIII laser facility. For the first time, the 32 laser beams are injected into the octahedral spherical hohlraum through six laser entrance holes. Two techniques are used to diagnose the radiation field of the octahedral spherical hohlraum in order to obtain comprehensive experimental data. The radiation flux streaming out of laser entrance holes is measured by six flat-response x-ray detectors (FXRDs) and four M-band x-ray detectors, which are placed at different locations of the SGIII target chamber. The radiation temperature is derived from the measured flux of FXRD by using the blackbody assumption. The peak radiation temperature inside hohlraum is determined by the shock wave technique. The experimental results show that the octahedral spherical hohlraum radiation temperature is in the range of 170-182eV with drive laser energies of 71kJ to 84kJ. The radiation temperature inside the hohlraum determined by the shock wave technique is about 175eV at 71kJ. For the flat-top laser pulse of 3ns, the conversion efficiency of gas-filled octahedral spherical hohlraum from laser into soft x rays is about 80% according to the two-dimensional numerical simulation.

UK Company Looks to Shrimp in Bid to Transform Fusion

Sea creature's shock-wave technique is the basis for £3.6m machine

Underwater shockwave pretreatment process for improving carotenoid content and yield of extracted carrot (Daucus carota L.) juice

Carrots (Daucus carota L.) are an important source of antioxidants with both lipophilic (carotenoids, xanthophylls) and hydrophilic (polyphenols) properties. In this study, we evaluate the yield and carotenoid content of the juice obtained upon subjecting carrots to an underwater shockwave pretreatment. There is a significant increase in the juice yield and a two-fold increase in the α- and β-carotene contents compared to that of raw carrot juice when a shockwave pretreatment of 5 cycles at 3.5 kV and 4.9 kJ is employed. The sugar concentration (°Bx) of the shockwave-treated carrot juice increases by 15.5% without a blanching process. The treatment method proposed here is a reliable and efficient technique for the extraction of functional antioxidant chemicals from carrots. This study demonstrates the broad applicability of the underwater shockwave technique for improving the carotenoid content in carrot juice, confirming its potential for application in a wide range of food extraction processes.

Focused Shockwave Induced Blood-Brain Barrier Opening

Blood-brain barrier (BBB) is a diffusion barrier, which impedes influx of most compounds, and controls the exchange of substances between the blood and the central nervous system (CNS) to maintain the physiological condition. Nonetheless, the protecting mechanism of BBB also prevents CNS drugs from treating CNS disorders effectively. In this study, a commercial focused shockwave was applied for inducing blood-brain barrier opening to improve the efficiency of drugs delivery. A commercial focused shockwave instrument (Piezowave, Richard Wolf GmbH) was combined with a computer controlled bi-axial locator, and four-point laser locator on transducer to process the shockwave induced blood-brain barrier opening. Evans blue was injected via tail vein as a BBB opening indicator. All Brain samples were collected 3 hr after shocking, and analyzed by H&E stain and TUNEL assay (S7100, Millipore). Under intensity level 5 (P- -10 Mpa, P+ 17.4 Mpa, 0.182 mJ/mm2) with 5 Hz of shocking, BBB was opened by 100 times of shocks (with above 50 % of success opening rate), and opened with bleeding by 300 times of shocks. With the proposed locating- mechanism, the target treating area could be located precisely, including the depth and the area on brains (SD rat). The proposed focused shockwave technique to induce blood-brain barrier opening has several advantages: consistent BBB opening rate, good penetration (due to low frequency), lack of thermal effect, and easy-accessibility (based on a commercial device).

First Investigation on the Radiation Field of the Spherical Hohlraum.

The first spherical hohlraum energetics experiment is accomplished on the SGIII-prototype laser facility. In the experiment, the radiation temperature is measured by using an array of flat-response x-ray detectors (FXRDs) through a laser entrance hole at four different angles. The radiation temperature and M-band fraction inside the hohlraum are determined by the shock wave technique. The experimental observations indicate that the radiation temperatures measured by the FXRDs depend on the observation angles and are related to the view field. According to the experimental results, the conversion efficiency of the vacuum spherical hohlraum is in the range from 60% to 80%. Although this conversion efficiency is less than the conversion efficiency of the near vacuum hohlraum on the National Ignition Facility, it is consistent with that of the cylindrical hohlraums used on the NOVA and the SGIII-prototype at the same energy scale.

Visualization of physical processes occurring on liquid nitrogen injection into water

Hydrodynamic processes occurring when cryogenic liquid is injected into water are experimentally investigated. Processes accompanying the phase transitions under these conditions were recorded. Optical recording of the processes revealed their structure and stages. It is shown that at the outer boundary of a cylindrical vapor bulb, active turbulent mixing is observed, which should be taken into account when one will develop a mathematical model of the process. At the gas–water interface, ice crystal structures were observed. The obtained results may be useful for studying a new method of gas hydrate production based on the shock-wave technique.

Discovering Phase Timing Information of Traffic Light Systems by Stop-Go Shockwaves

The cycle lengths and signal transition time of Traffic Light Systems ( TLS’s ), or known as the Phase Timing Information ( PTI ), play a key role in modern transportation systems. However, such information is not always available to the public. In this paper, we propose a crowdsourcing approach to solve this problem by exploiting the stop and go events, abbreviated by SG events, of vehicles on roads happening in front of target traffic lights. The PTI discovery problem is formulated by allowing only part of the vehicles participating in the discovery process. The proposed framework starts with discovering SG events, followed by collapsing these events over multiple signal cycles into one and calculating PTI information through a shockwave technique. The crowdsourcing part may be directly implemented on smartphones. The proposed framework was verified via field trials and simulations. Our simulation results showed that, even with a low penetration rate around $3.8$ percent, the root mean square errors of the cycle length, green light and red light signal transition time of a TLS are $0.04$ , $1.3$ and $5.8$ seconds, respectively. The achieved accuracy can be helpful in many PTI-enabled applications.

Cladding of titanium and magnesium alloy plates using energy-controlled underwater three layer explosive welding

Titanium and magnesium alloy AZ31 plates were explosively welded using the underwater shock wave technique. A thin AZ31 interlayer was utilized as a proposed method to reduce kinetic energy loss and the formation of excessive molten zone at the interface. Through the experiments, the effects of initial inclined angle of the explosive, water distance and annealing of the AZ31 plates were investigated. Different experimental conditions allowed confirmation of the excessive molten zone, moderately welded zone and separation zone. Characterization of the welded interface suggests that bonding quality in the welded region showed planar interface without a molten zone. The effects of various welding parameters are discussed to evaluate moderate conditions of explosive welding. Welding conditions are discussed based on a weldability window estimated by numerically simulated dynamic bending angle at collision and horizontal collision point velocity, which may provide the kinetic energy lost by collision.

Ignition of ethanol-containing mixtures excited by nanosecond discharge above self-ignition threshold

The kinetics of ignition in lean and stoichiometric C2H5OH:O2:Ar mixtures by a high-voltage nanosecond discharge are studied experimentally and numerically for gas temperatures above self-ignition threshold. Autoignition delay time and ignition delay after a high-voltage nanosecond impulse discharge are measured using reflected shock-wave technique. It is shown that the additional excitation by the discharge plasma leads to an order of magnitude decrease in ignition delay. Discharge processes are simulated on the basis of the measured time–resolved discharge characteristics. The densities of atoms, radicals and excited and charged particles produced in the discharge phase are calculated and used as initial conditions for chemical modeling. Calculated ignition delay times agree well with measurements with and without the discharge plasma. Calculations show that the effect of the discharge plasma on ignition of the ethanol-containing mixtures is primarily associated with active species production in the discharge phase; the role of fast gas heating during the discharge and in its afterglow is relatively small. A method is suggested to compare the effect of nonequilibrium pulse discharge plasma on ignition in different fuel–air and fuel-oxygen mixtures above self-ignition temperatures. It is shown that this effect is more profound at low gas temperatures when the thermal production of initial radicals is not efficient. Due to O2 dissociation in the discharge phase, the influence of nonequilibrium discharge plasma on ignition is more pronounced for fuels with high activation energy of thermal dissociation (like H2 and CH4). The role of N2 in favoring plasma-assisted ignition owing to additional O2 and fuel dissociation is demonstrated.

The radiation temperature andM-band fraction inside hohlraum on the SGIII-prototype laser facility

The radiation temperature TR and M-band fraction fM inside the vacuum Au hohlraum have been experimentally determined by a shock wave technique and a broadband soft x-ray spectrometer (SXS) on the SGIII-prototype laser facility. From the results of the shock wave technique, TR is about 202 eV, and fM is about 9% for the hohlraums driven by a 1 ns flattop pulse of 6 kJ laser energy. The Continuous Phase Plate (CPP) for beam smoothing is applied in the experiment, which increases TR to 207 eV while has almost no influence on fM. Comparisons between the results from the two kinds of technologies show that TR from the shock wave technique is lower than that from SXS whether with CPP or not. However, fM from the shock wave technique is consistent with that from SXS without CPP, but obviously lower than the SXS's result with CPP. The preheat effect on exterior surface of witness plate is reduced by thicker thickness of witness plate designed for higher laser driven energy.

Formation and properties of rocksalt-type AlN and implications for high pressure phase relations in the system Si–Al–O–N

Pressure-dependent thermodynamic properties of the ambient and high pressure phases of aluminum nitride (w-AlN and rs-AlN) were calculated from first principles in order to determine their phase boundary in the p− T phase diagram. These predictions were checked by static HP/HT experiments, using a multianvil press and an Al/N/H precursor with low decomposition temperature as educt. The experimental data show that at temperatures between 1000 and 2000 K, the boundary line between the two phases is situated between 11 and 12 GPa, which is ∼1.3 GPa lower than the theoretical result and generally lower than previously assumed. The hardness of rs-AlN – measured for the first time – is ∼30 GPa (Knoop indenter at loads of 25–50 g), twice as hard as w-AlN. Shock wave recovery experiments on nano w-AlN allowed testing of the chemical and thermal stability of rs-AlN, and determination of its infrared absorption and 27Al NMR data. The shock wave technique will eventually enable the synthesis of larger amounts of rs-AlN, making it available for technological use. Finally, implications on the high pressure stability of phases in the Si–Al–O–N system are discussed in the light of thermoelastic properties of AlN.