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Objective To investigate the CT imaging features and pathological results of pulmonary inflammatory myofibroblastic tumor, and to improve the awareness of this disease in clinical practice. Methods A retrospective analysis was performed for the clinical data, CT imaging features, and pathological results of 28 patients who were diagnosed with pulmonary inflammatory myofibroblastic tumor by surgery or lung biopsy. Results All 28 patients had a solitary lesion, among whom 21 had a lesion located in the left and right lower lobes of lungs. Plain CT scan showed inhomogeneous density of the lesion in 21 patients, lesions with smooth margins in 12 patients, and lesions with unsmooth margins in 16 patients, and contrast-enhanced CT scan showed obvious heterogeneous enhancement in 9 patients, flat sign in 12 patients, peach-tip sign in 7 patients, and long spiculation sign in 11 patients. Immunohistochemistry showed positive expression of Vimentin in 26 patients, SMA in 19 patients, ALK in 9 patients, CD-68 in 12 patients, and CD-99 in 9 patients and negative expression of CK in 14 patients, S-100 in 8 patients, and CD-34 in 13 patients. Conclusion The specific imaging findings of pulmonary inflammatory myofibroblastic tumor may help with early clinical diagnosis, and a combination of histopathology and immunohistochemistry is of great significance for prognostic eva-luation and postoperative diagnosis and treatment.

In subsurface energy extraction, permeability or conductivity is the vital parameter for quantifying fluid flow in porous media. Three-dimensional digital core technique is widely used to calculate flow parameters and to analyze the internal structure and properties of rocks. However, one major problem is its high computational cost associated with fine-scale simulation of porous media, especially for large and complex rock samples. In this study, we propose to use subvolume properties to increase computational efficiency. Specifically, we first construct digital cores of dune sand and sandstone by CT scanning technology, and divide the whole core into multiple subvolumes and calculate their permeabilities. Then, we reassemble the subvolumes and compute the permeability for the whole core. This approach may lead to underestimation as the connectivity between subvolumes could be lost. To address this issue, we divide the whole core into different-sized subvolumes, and then use curve fitting to deduce the permeability of whole rock sample via extrapolation. The results show that the proposed method has improved accuracy, and is significantly faster than simulating the whole digital core, since the computation on subvolumes can be easily parallelized. This approach provides new ideas for accurate and efficient permeability estimation for digital porous media. [ABSTRACT FROM AUTHOR]

The aim of topology optimisation is to determine the optimal distribution of material phases within the periodic cells of a microstructure. In this paper, the density of grid points under element volume fraction is constructed to replace the finite elements in the traditional SIMP framework, avoiding jagged and blurry boundaries in the computational process due to grid dependence. This is then combined with homogenisation theory, a microstructure topology optimisation algorithm with maximum bulk modulus under prescribed volume constraints is proposed, which can obtain 2D and 3D topologies with smooth boundaries. In addition, a closed form expression for the two-dimensional topological concave edge structure (taking the most typical topology as an example) was derived, and a compression experiment was conducted on the topological microstructure based on 3D metal printing technology. Scanning electron microscopy showed that the powder bonded on the surface of the printed structure was not completely melted and the step effect caused the finite element analysis results to be higher than the experimental results. Overall, the finite element simulation and experimental results of the concave surface structure have good consistency, with high strength and energy absorption effects. Topologies based on grid point density obtain microstructures with smooth boundaries, and the introduction of the Heaviside smoothing function and multiple filtering steps within this algorithm leads to more robust optimisation, facilitating 3D or 4D printing of microstructures that meet specific design requirements and confirming the feasibility of the proposed topology for lightweighting studies. [ABSTRACT FROM AUTHOR]

The author prepared specimen of glass fiber-hollow glass microsphere/epoxy syntactic foam material. We have obtained the load-displacement curves by three point bending test,studied the influence of glass fiber content on the bending strength and bending elastic modulus. Through soaking test,we measured the curves of moisture rate of the specimen in H2SO4 and Na OH solution over time. Through the scanning electron microscopy images,we analyzed the effect of acid-base corrosion on the bending properties. The research results showed that when the glass fiber quality ratio is 10%,the bending strength of the composite reached the maximum value,rising by 27% than the specimen without glass fiber. When added more fiber,its strength is gradually reduced. Acid-base soaking corrosion greatly reduces the bending strength of syntactic foam material. The direct reason is that acid-base solution will corrode the interface of glass fiber and epoxy matrix. It also will corrode epoxy matrix.

The dynamic mechanical properties of aluminum honeycomb sandwich panels were investigated under low velocity drop weight impact test.The failure behaviors,destruction process and typical force-displacement curves were analyzed.The impact velocities and panel thickness have influence on ultimate impact force and energy absorption was analyzed respectively.The mechanical properties of sandwich panels with corresponding panel thickness under quasi-static test were compared.The tests result show that typical impact load-displacement curve of aluminum honeycomb sandwich panels presents five stages.The ultimate impact force and energy absorption of sandwich panels under different impact velocities are basically identical.With the panel thickness increasing,ultimate impact force and energy absorption of sandwich panels increase.Compared with quasi-static experiment,the ultimate impact force and energy absorption of sandwich panels with three kinds surface thickness under low velocity drop weight impact tests are improved.

Quasi-static localized indentation tests were carried out to investigate the indentation mechanical properties of the aluminum honeycomb sandwich panels. The destruction process,failure behaviors and typical force-displacement curves were analyzed. The impact of surface plates thicknesses,aperture sizes,intender types and boundary conditions on the ultimate load and energy absorption capacity were studied. The results indicate that the aluminum honeycomb sandwich panels have two kinds of typical force-displacement curves,and six stages are presented: elastic stage,local destruction stage,intensify stage,entirely damage stage,compression density stage and bottom damage stage. Surface plates thickness and aperture size have certain influence on load bearing capability and energy absorption capacity. Indenter types have much influence on load bearing capability and rigidity,but little influence on the energy absorption capacity. Different boundary conditions and core thicknesses have less influence on strength and energy absorption capacity of aluminum honeycomb sandwich panels.

The mechanical properties of hollow glass microsphere/epoxy resin syntactic foams reinforced by short glass fibers are studied using representative volume elements. Both the glass fibers and the hollow glass microspheres exhibit random arrangement in the epoxy resin. The volume fraction and wall thickness of hollow glass microspheres and the volume fraction of glass fibers are considered as parameters. It is observed that the elastic modulus values of syntactic foams decrease with the increase of microsphere volume fraction when the microsphere relative wall thickness is lower. However, it increases with the increase of microsphere volume fraction when the relative wall thickness exceeds a critical value. The elastic modulus value goes through a maximum when the relative wall thickness is around 0.06 at 25 % volume fraction of microspheres. The addition of glass fibers reduces the critical wall thickness values of the microspheres and increases the mechanical properties of the composites. The highest stress lies on the equatorial plane perpendicular to the loading direction. Adding fibers reduces the large stress distribution areas on the microspheres, and the fibers aligned with the loading direction play an important load-bearing role.

The mechanical properties of hollow glass microsphere / epoxy syntactic foam can be reinforced by adding glass fiber. Two numerical simulation models have been established with two different hollow glass microsphere and glass fiber arrangements. The change rules between elastic constants and volume fraction,relative wall thickness and stress distribution rules are studied. It is found that the elastic modulus of composites increases with the increase of glass microsphere relative wall thickness,while the changing rules with volume fraction show different patterns in different relative wall thickness. Poisson’s ratio decreases with volume fraction increase,but it increases before then reduce with the relative wall thickness. The elastic modulus prediction formula along the fiber axial was proposed according to Voigt model and mix law. The prediction results are close to numerical simulation results when the relative wall thickness less than 0. 2.

In this paper, a new hybrid structure of body-centered cubic lattice-filled thin-walled tube is designed, and the hybrid structure specimens of one-piece printing and split-printing are prepared by laser melting technique. The deformation mode and energy absorption characteristics of the new hybrid structure are investigated by experiments and numerical simulations. Under axial compression, the one-piece printed hybrid structure forms more wrinkles with smaller wavelengths, and the specific energy absorption increases by 12.14% compared with the split-printed structure; under transverse compression, the one-piece printed structure does not show the separation of the thin-walled tube from the lattice, and the specific energy absorption increases by 134.83% compared with the split-printed structure. It is worth noting that the designed hybrid structure has a 112.60% (580.15%) increase in specific energy absorption under axial compression (under transverse compression) compared to the empty tube. The effects of wall thickness, lattice density, and loading rate on the crashworthiness of the hybrid structure were investigated using a validated finite element model. This paper provides a new idea for the preparation of lightweight and high-strength energy-absorbing structures. [ABSTRACT FROM AUTHOR]