Cavity Layout Research Articles

Design of Injection Mould for Lithium Battery Heat Dissipation Device Connector Bottom Cover

The design process of the injection mould for the Lithium battery heat dissipation device connector bottom cover is described in detail. In the design process, the UG software is used to establish the three-dimensional model of the plastic part, and the mould flow analysis is carried out with the help of the moldflow software to determine the optimal gate position of the plastic part. By determining the injection process parameters of Lithium battery heat dissipation device connector bottom cover material, the design of the cavity layout of the plastic part is completed, and the basic size and mould structure of the mould base are determined. Then, the UG injection mould design guide module was used to carry out the parting design, and the structural design of the mould’s gating system, molding parts, lateral parting mechanism, core-pulling mechanism, ejection mechanism, exhaust system and cooling system was completed in turn. The whole design process improved the efficiency of mould design and saved a lot of time and cost.

Improving the energy release of a latent heat storage with multiple phase change materials loading and partition shaping

This paper presents a theoretical study of the integration of two selected phase change materials (PCMs) into a vertical shell and tube latent-heat thermal energy storage unit. Various cell shapes and PCM arrangements are analyzed for their heat release characteristics and compared to a reference unit. Using the finite volume method with an enthalpy-porosity formulation, the study simulates conjugate heat transfer between an isothermal wall and PCMs. This approach examines the impact of both the delay of the phase transition and the layout of the PCM cavities on natural convection. The findings indicate that these factors have a significant influence on energy transport. Delaying the solidification process near the cold wall can lead to a substantial reduction in the phase transition time. Furthermore, triangular cross-section cells improve convection and increase the solidification and complete energy discharge times by 42.7% and 25.3%, respectively. The energy charging performance is also enhanced by 39.7%.

Numerical Investigation on Internal Structures of Ultra-Thin Heat Pipes for PEM Fuel Cells Cooling

Proton exchange membrane fuel cell (PEMFC) powered propulsion has gained increasing attention in urban air mobility applications in recent years. Due to its high power density, ultra-thin heat pipe technology has great potential for cooling PEMFCs, but optimizing the limited internal cavity of the heat pipe remains a significant challenge. In this study, a three-dimensional multiphase model of the heat pipe cooled PEMFC is built to evaluate the impact of three internal structures, layered, spaced, and composite, of ultra-thin heat pipes on system performance. The results show that the heat pipe cooling with the composite structure yields a lower thermal resistance and a larger operating range for the PEMFC system compared to other internal structures because of more rational layout of the internal cavity. In addition, the relationship between land to channel width ratio (LCWR) and local transport property is analyzed and discussed based on composite structural heat pipes. The heat pipe cooled PEMFC with a LCWR of 0.75 has a significant advantage in limiting current density and maximum power density compared to the LCWRs of 1 and 1.33 as a result of more uniform in-plane distributions of temperature and liquid water within its cathode catalyst layer.

Validation of a shape-optimized 2-unit cantilevered inlay-retained fiber-reinforced resin-bonded dental prosthesis

Statement of problemCurrent designs of fiber-reinforced composite (FRC) resin-bonded fixed dental prostheses (RBFDPs) have a limited lifespan, failing mainly through veneer-fiber delamination, debonding, and fracture. PurposeThe purpose of this in vitro study was to validate a new inlay-retained 2-unit cantilevered RBFDP with an optimized cavity and fiber layout proposed in a previous study by using simulated occlusal loading. Material and methodsTwo groups of specimens (n=20), 1 with and 1 without glass fibers, were used to test the influence of the cavity design and that of the fiber layout on their load capacity, respectively. The specimens without fibers were directly cut from a resin-ceramic block by using a computer-aided manufacturing system, while those with fibers were manually fabricated with unidirectional glass fibers and composite resin in a silicone mold. The specimens with and without fibers were attached to abutments made of the same resin-ceramic with a cyanoacrylate-based adhesive and a resin-based dental cement, respectively. An increasing compressive load was applied on the mesial fossa of the premolar pontic until failure. Cracking in the specimens during loading was monitored with a 2-channel acoustic emission (AE) system. ResultsAll the specimens without fiber reinforcement debonded from the abutments. Those using the optimized shovel-shaped cavity design had a mean ±standard deviation failure load (50.0 ±17.3 N) that was 193% higher than that of those with the conventional step-box design (17.1 ±6.2 N; P<.001). No significant difference was found between the groups for the mean number of AE events per specimen (step-box: 49 ±34 versus shovel-shaped: 63 ±34; P=.427), the mean amplitude of each event (58.4 ±1.3 dB versus 59.5 ±2.4 dB; P=.299), or the mean time to failure (283.2 ±122.3 seconds versus 297.5 ±66.7 seconds; P=.798). Between the groups of specimens with reinforcing fibers, the mean failure load of the conventional design was approximately half that of the optimized one. Again, no significant difference was found for the mean number of AE events per specimen (conventional: 28 ±18 versus optimized: 52 ±53; P=.248) or the mean amplitude for each AE event (64.9 ±4.2 dB versus 61.7 ±5.2 dB; P=.187). The connectors of 8 fiber-reinforced specimens with the conventional design fractured; the other 2 debonded from the abutments. Half of the shape-optimized fiber-reinforced specimens had fractured abutments, but the cantilevers remained intact, 4 specimens fractured at the connector, and only 1 debonded from its abutment. ConclusionsThe shape-optimized 2-unit cantilevered FRC RBFDP had a higher load capacity than the conventional design.

The Layout of the Combustion Cavity and the Fracture Evolution of the Overlying Rock during the Process of Underground Coal Gasification

Based on the thermodynamic and elastodynamic theories, the controlling equation of temperature-stress coupling action on rocks containing random damage units is established by combining the Mogi-Coulomb damage criterion. And the numerical calculation model of combustion cavity expansion under temperature-stress coupling condition is established by using ABAQUS secondary development program. The fracture field evolution law during the expansion of the gasification cavity was studied under two conditions: perpendicular to (condition 1) and along the intermediate principal stress (condition 2). It is found that under the condition 1, the gasification cavity gradually forms a smaller fracture circle, while the surrounding rock at the floor of the gasification cavity generates a wide range of equivalent damage areas under the condition 2, which is unfavorable for practical engineering. The condition 1 deployment scheme is more practical in terms of the degree of rupture and the subsequent gasification process. The gasification cavity is obviously affected by the horizontal stress. When the horizontal stress is small, the stability of the surrounding rock is seriously damaged. It is necessary to fully consider the influence of in situ stress in the layout of the gasification cavity; at the same time, measures are added to the process to reduce the degree of rupture of the surrounding rock. The evolution law of the temperature field and rupture field of the surrounding pressure in the combustion cavity during the whole process of UCG was numerically simulated. The floor rupture zone develops gradually with the advancement of the working face of the combustion cavity, and deeper rupture zones appear in several areas, which need special attention in the engineering.

Analysis of mechanical behaviour and fracture interaction of multi-hole rock mass with DIC measurement

To study the mechanical properties and fracture behaviour of rock containing multiple cavities, uniaxial compression experiments were carried out on marble specimens with three rectangular cavities of different layouts. The fracturing behaviour was revealed by digital image correlation (DIC) measurement. Then, discrete element method (DEM) numerical simulations were performed and the stress evolution was analysed to reveal the influence of cavity layout on fracture behaviour and coalescence patterns between them. Results showed that stress evolution and failure coalescence pattern between two cavities can be directly or indirectly influenced by the third cavity. The compressive stress concentrated around the sidewalls of a cavity may suppress the propagation of tensile cracks from other cavities. Combining laboratory and numerical results shows that during the failure evolution, firstly comes the internal coalescence of cavities before instability point, then follows failure from the three-cavity system boundary to the specimen borders resulting in the whole instability.

Compact, diode-pumped, unstable cavity Yb:YAG laser and its application in laser shock peening.

We present the setup of a compact, q-switched, cryogenically cooled Yb:YAG laser, which is capable of producing over 1 J output energy in a 10 ns pulse at 10 Hz. The system's design is based on the recently published unstable cavity layout with gain shaping of the spatial intra-cavity intensity distribution. Using a hexagonal homogenized pump beam, the laser generated an according hexagonal output beam profile. The suitability of such laser properties for the intended use in a laser shock peening process is demonstrated. In the experiment an aluminum plate was treated and the generated residual stresses in the sample subsequently measured. Other applications of this laser system like laser pumping or surface cleaning are conceivable.

Research on feature of thermal performance of integrated composite system

Abstract The aim of this study is to explore the effect of stud on the characteristics of thermal insulation and decoration composite system. Prior research conducted has primarily focused on the insulation material performance aside from the composite system. The theoretical calculation and field measurement method are adopted in this paper to compare the insulation performance for different building envelope systems. By considering the thermal transfer coefficient as the performance indicator, thermal bridge and air cavities of integrated insulation composite system as impact factors are investigated. Firstly, the high insulation performance of the composite system is determined via comparing other systems. Secondly, the thermal bridge issue of the composite system led by stud is subsequently investigated followed by the air cavity influenced element being studied via field measurement, which is caused by stud condition. Final results indicate that the thermal insulation and decoration composite system can achieve a substantial insulation performance. In this case, the corresponding optimal size of studs and air cavity is achieved. Further, scattered layout of air cavities could apparently improve the entire thermal system’s insulated performance. All these studied conclusions can contribute designers to implement this system more accurately.

Simulation Based Optimization of Thin Wall Injection Molding Parameter Using Response Surface Methodology

.Improper mold design or processing parameter setting could make a bad impact on the appearance of molded part. It becomes more challenging if the ratio of the part size compared with its wall thickness is greater. Process parameters such as mold and melt temperature, injection temperature including the cavity layout directly affect product quality and cost. It is a complex and difficult task to improve these multi parameters. The objective of this research is to determine optimum settings for processing parameters for a thin walled product by using Response Surface Methodology. Melting temperature, mold temperature, injection pressure and cavity layout are selected as processing parameters and Polyurethane material is selected for this research. Volumetric shrinkage and warpage are selected as the main quality criteria to be controlled respected with the product design specifications. As the result, optimum process parameter settings were mold temperature of 29.89°C, melting temperature of 220°C, and 181.30MPa injection pressure with ‘H’ branching cavity layout. With small differences error value between solution and simulation, 0.31% for volumetric shrinkage and 0.126% for warpage, the result was acceptable.

Investigation on the neighbouring effect of filling micro‐ and nanoscale cavities in ultraviolet nanoimprint lithography

Micro-/nanoscale patterns are popular in many applications, and several techniques to transfer multiscale patterns have been developed. Ultraviolet nanoimprint lithography (UV-NIL) is the most promising method to quickly produce complex structures, and there is a need to understand the resist-flowing and cavity-filling processes because partial cavity filling may cause defects. One crucial element of a stamp is the layout of the multiscale cavities. They can induce some difficulties during the filling process. Five different stamps with various micro-/nanoscale features (one nano feature, one micro feature, one nano feature, and one micro feature, two nano features and one micro feature) were employed in this simulation study. The imprint results show that the neighbouring effect has major issues in the microscale cavity filling and minor issues in the nanoscale. The layout of complex cavities results in poor filling proportions, and longer imprint times and a symmetrical layout were needed to improve the imprint quality. The contact pressure between the stamp and the resist generally declined when the location approached the centre from both sides of the stamp. The overall physical performance of neighbouring micro-/nanoscale cavities was obtained, and this is essential for further understanding and improvements in the UV-NIL process.

High-efficiency broadband THz emission via diffraction-radiation cavity

Accelerator-based terahertz (THz) radiation has been expected to realize a high-power broadband source. Employing a low-emittance and short-bunch electron beam at a high repetition rate, a scheme of coherent diffraction-radiation in an optical cavity layout is proposed. The scheme's stimulated radiation process between bunches can greatly enhance the efficiency of the radiation emission. We performed an experiment with a superconducting linac constructed as an energy recovery linac (ERL) test facility. The electron beam passes through small holes in the cavity mirrors without being destroyed. A sharp THz resonance signal, which indicates broadband stimulated radiation correlated with beam deceleration, was observed while scanning the round-trip length of the cavity. This observation proves the efficient beam-to-radiation energy conversion due to the stimulated radiation process.

Compact Storage Ring for an X-Ray Source

We propose a new design of a compact storage ring for a source of X-ray radiation on the basis of reverse Thomson scattering of laser radiation by electrons with the energy of 35–50 MeV, which has small number of optical elements and a significant clear space for the placement of a beam injection-extraction system and a RF cavity. The original laser cavity layout has been considered. The ring dynamic aperture after correction of chromaticity and a second-order dispersion function is sufficient for the injection and stable circulation of an electron bunch in the ring.

Influence of clamping force on tie-bar elongation, mold separation, and part dimensions in injection molding

In injection molding, the magnitude of clamping force may affect the quality of plastic parts. A small clamping force may produce defects such as flashes and poor geometrical accuracy, whereas a large force could result in insufficient air venting during mold filling/packing, leading to the generation of short shot. Traditionally, clamping force is set at the highest machine specification, which may lead to additional energy consumption. Moreover, heavy loading at the tie bars is detrimental to the durability of processed molds and the machine itself. In this study, we developed a measuring system for recording tie-bar elongation and mold separation during injection molding at each corner of the mold. To determine the consequences of proper and improper clamping force settings on the quality of injection-molded parts, we systematically evaluated the effects of relevant parameters such as cavity layout and gate location on cavity pressure distribution during packing and the reactive force from cavity pressure acting on mold walls. Correlation analysis on experimental results depicted that the maximum increase in tie bar elongation and the maximum mold separation during injection molding are highly correlated with the thickness of plastic parts, and we suggested that the two features are good indicators of part quality. Moreover, cavity layout of generating diverse filling patterns and the distribution of cavity pressure is influential to mold separation as well as tie-bar elongation during mold filling. This phenomenon is further change the degree of mold separation at each corner of the injection mold and should be concerned in practice.

Fracture evolution and failure behaviour of marble specimens containing rectangular cavities under uniaxial loading

To analyse the fracture coalescence behaviour around hole-like flaws in rock, rectangular cuboid marble specimens containing a single rectangular cavity or two rectangular cavities with different layouts were tested under uniaxial compression. Failure characteristics of specimens and strain concentration regime (SCR) evolution on specimen surfaces were measured by means of acoustic emission (AE) and digital image correlation (DIC) techniques respectively. Numerical simulations were further conducted on specimens with the same specimen and cavity dimensions using the discrete element method (DEM), and the inclination angle between centroids of two cavities with respect to the horizontal direction was varied to investigate its influence on failure modes and mechanical properties of specimens. Results showed that both cavity number and layout have a significant influence on mechanical behaviour of marble specimens. The existence of two cavities leads to more degradation of mechanical properties than a single cavity. For specimens with two cavities, the strength first decreases and subsequently increases with increasing inclination angle, and the specimen with two vertically aligned cavities has the maximum strength. Four failure modes were observed in specimens, namely splitting failure, shear failure, mixed tensile/shear failure, and surface spalling. In addition, absorbed energy per unit volume e was introduced to characterise the fragmentation of different groups of specimens. Specimens containing cavities absorbed less energy per unit volume, and thus were less fragmented after failure.

Discrete tuning concept for fiber-integrated lasers based on tailored FBG arrays and a theta cavity layout

We demonstrate a novel tuning concept for pulsed fiber-integrated lasers with a fiber Bragg grating (FBG) array as a discrete and tailored spectral filter, as well as a modified laser design. Based on a theta cavity layout, the structural delay lines originating from the FBG array are balanced, enabling a constant repetition rate and stable pulse properties over the full tuning range. The emission wavelength is electrically tuned with respect to the filter properties based on an adapted temporal gating scheme using an acousto-optic modulator. This concept has been investigated with an Yb-doped fiber laser, demonstrating excellent emission properties with high signal contrast (>35 dB) and narrow linewidth (<150 pm) over a tuning range of 25 nm.

Structural failures due to anthropogenic sinkholes in the urban area of Naples and the effect of a FRP retrofitting

Abstract This work is about the hypothesis of structural health monitoring of architectural heritage in masonry exposed to collapse risk in the city of Naples. We analyze the collapse mechanisms in static terms relating the planimetric layout of the underground cavities of Naples with some recent collapses of structures that occurred in the city. The present work focuses on the relationship between these collapses and the presence of underground cavities. Constructions in masonry, contrary to common opinion, are structures that provide comparatively level of safety depending on to the strength of materials and construction techniques adopted, together with the fact that they are able to settle and to find a new equilibrium configuration; in other words they embody the prototype of resilient structures. The main critical issue able to put in crisis a huge masonry building is the subsoil subsidence. In fact, the structure reaches the collapse for the creation of cavities or chasms under it, which literally remove the support surface of its foundation. In particular, the present work aims to analyze the collapse of two buildings of the Department of Veterinary Medicine of Federico II, that occurred in Naples last December and, starting from a real case of the collapse of a masonry building, the research aims to correlate this collapse with one of the cavities present in the subsoil of Naples and evaluate the possibility that the cause of the collapse to be related the corresponding cavity (or to a newly formed) situated below a corner of the building. The effect of a possible retrofitting intervention, consisting in three FRP strips glued to the surface of the structure, is also considered.

Filter-Based Dispersion-Managed Versatile Ultrafast Fibre Laser.

We present the operation of an ultrafast passively mode-locked fibre laser, in which flexible control of the pulse formation mechanism is readily realised by an in-cavity programmable filter the dispersion and bandwidth of which can be software configured. We show that conventional soliton, dispersion-managed (DM) soliton (stretched-pulse) and dissipative soliton mode-locking regimes can be reliably targeted by changing the filter’s dispersion and bandwidth only, while no changes are made to the physical layout of the laser cavity. Numerical simulations are presented which confirm the different nonlinear pulse evolutions inside the laser cavity. The proposed technique holds great potential for achieving a high degree of control over the dynamics and output of ultrafast fibre lasers, in contrast to the traditional method to control the pulse formation mechanism in a DM fibre laser, which involves manual optimisation of the relative length of fibres with opposite-sign dispersion in the cavity. Our versatile ultrafast fibre laser will be attractive for applications requiring different pulse profiles such as in optical signal processing and optical communications.

Development of Semi-Solid Die Casting Process Technology for Aluminium Alloy Clamp

Compared with traditional liquid and solid processing methods, semi-solid die casting process can apparently overcome shrinkage cavity and porosity defects in castings and high deformation resistance and high residual stress shortcomings in forging parts. Semi-solid die casting process with advantages such as high efficiency and low cost, will become the optimal process for high quality automobile parts. In this study, using the clamp as an example, the author introduced product structure optimization and die design for semi-solid die-casting process of aluminum alloy in a new product development.The Computer Aided Engineering technology was applied to the product structure optimization according to the stress analysis. The optimal mold structure, including cavity layout, gating system, overflow and vent systems, were confirmed based on the die design criteria for traditional die casting, combining with the characteristics of semi-solid forming and the simulation results. The semi-solid aluminum alloy clamp parts with excellent performances were finally developed successfully by means of product structure optimization, die design, parameters optimization of die casting process, and the mechanical properties test of products.The existing parts were optimized to make them more suitable for semi-solid die casting processing. In addition, a reasonable die design specially for semi solid processing was an important guarantee for a successful semi solid product applied in industry. Computer numerical simulation was applied in product structure design for semi-solid die casting, die design, die-casting process optimization and other aspects, to shorten the development cycle of new product, reduce cost and improve efficiency.

Dual-gain SESAM modelocked thin disk laser based on Yb:Lu₂O₃ and Yb:Sc₂O₃.

We present for the first time a SESAM-modelocked thin-disk laser (TDL) that incorporates two gain materials with different emission spectra in a single TDL resonator. The two gain media used in this experiment are the sesquioxide materials Yb:Lu2O3 and Yb:Sc2O3, which have their spectral emission peak displaced by ≈7 nm. We can benefit from a combined gain bandwidth that is wider than the one provided by a single gain material alone and still conserve the excellent thermal properties of each disk. In these first proof-of-principle experiments we demonstrate pulse durations shorter than previously achieved with the single gain material Yb:Lu2O3. The oscillator generates pulses as short as 103 fs at a repetition rate of 41.7 MHz and a center wavelength of around 1038 nm, with an average output power of 1.4 W. A different cavity layout provides pulses with a duration of 124 fs at an output power of 8.6 W. This dual-gain approach should allow for further power scaling of TDLs and these first results prove this method to be a promising new way to combine the record output-power performance of modelocked TDLs with short pulse durations in the sub-100 fs regime.

Computation fluid dynamics analysis of the Reactor Cavity Cooling System for Very High Temperature Gas-Cooled Reactors

The design of passive heat removal systems is one of the main characteristics of the modular Very High Temperature Gas-Cooled Reactors (VHTR) vessel cavity. The Reactor Cavity Cooling System (RCCS) is a key heat removal system during normal and off normal conditions. The design and validation of the RCCS is necessary to demonstrate that VHTRs can survive the postulated accidents. The commercial Computational Fluid Dynamics (CFD) STAR-CCM+/V5.02.009 code was used for three-dimensional system modeling and analysis of the RCCS. Different RCCS geometries and configurations were investigated to analyze heat exchange in the VHTR cavity. Sensitivity analyses over the RCCS cavity height and cooling panel location with respect to the reactor pressure vessel (RPV) wall were performed. The objective of the present work was to use CFD tools for addressing the behavior of the RCCS following accident conditions.Heat removal from the RPV through the RCCS system during normal and off normal conditions is accomplished through radiation, convection and conduction heat transfer modes. The interaction of all three heat exchange mechanisms makes it very challenging to have an accurate description of the RCCS heat transfer dynamics during normal and transient conditions. A systematic analysis of the cavity layout was performed to address the influence of different geometrical parameters on the balance of heat transfer across the RCCS cavity. Mesh convergence was achieved with an intensive parametric study of the different geometrical configurations and boundary conditions selected. Based on the results of previous studies, the Realizable k–ε turbulence model with Two-Layer all y+ wall treatment was used for the analyses discussed in the present work. The numerical results demonstrated that the CFD analyses can resemble the behavior of the full RCCS system from an integral effect point of view, with the main physical phenomena accurately reproduced by the CFD model.