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Split Hopkinson Pressure Bar (SHPB) has become a frequently used technique for measuring uni-axial compressive stress-strain relationship of various engineering materials under high strain rates. The pulse shape generated in the incident bar is sensitive to the length of the striker bar. In this paper, a finite element simulation of a Split Hopkinson Pressure Bar is performed to estimate the effect of varying length of striker bar on the stress-strain relationship of a material. A series of striker bars with different lengths, from 200mm to 350mm, are employed to obtain the stress-strain response of AL6061-T6 in both simulation and experiment. A comparison is made between the experimental and the computed stress-strain curves. Finally the influence of variation of striker bar length on the sample's stress-strain response is presented.

Flexible radio-frequency (RF) capacitors and inductors on the plastic substrates have been fabricated and characterized under mechanical bending conditions. A novel method to predict the RF performance for them on different bending states is demonstrated. Artificial neural network (ANN) shows good modeling accuracy for the flexible RF passive components with bending strains from dc to resonant frequency ($\sim 13/2$ GHz for the capacitor/inductor). More importantly, the automatically generated ANN model, with no need of repeatedly tuning the model parameters, has demonstrated the ability to predict the RF responses for the flexible capacitors and inductors under arbitrary bending conditions with only a few sets of experimental data. Once established, this model can automatically learn the structure of the input date and predict the actual results on specific bending state which can provide an original method to measure the performance for flexible electronics on even extreme bent radius. The ANN model indicates good potential for accurate design, characterization and optimization of the high-performance flexible electronics.

Disparate industry bodies across the planet use pallets for storing large and heavy objects. Pallets provide an assurance of safe handling of material (cargo) and storage of material in a damage-free environment. In this work, an attempt has been made to analyze and investigate making pallets out of ULTEM 9805 using the latest additive techniques (FDM). The maximum deflections and von Mises stresses are analyzed for the disparate boundary conditions indicating the possible alternatives or loads to be used. Study of surface (morphology) and characteristics was done in order to establish the relationship between pallet surface and its application. The factors of load, maximum and minimum values, ascertained in each stage are 168.15, 522.22, 215.31 and 316.79 kPa as well as 18.77, 6.7, 1.2 and 35.84 kPa for the floor, rack, forklift and conveyor load supports, respectively. A cross-hatched design causes a rise in capacity of the shear factor owing to the length of the span being in correlation with rectilinear fill. The filament of surface, made of ULTEM 9805, exhibits a level of roughness of 43.14 μm on the pallet surface indicating better holding capacity and grip. A 9^∘ peak shift is comprehended with respect to XRD, indicating a compressive residual factor measured at 76.47 MPa.

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Intentional buckling as a fabrication technique for arch frameworks results in prestrains at every section of the arch, which in turn affect its strength and stability. A nonlinear corotational straight beam element with elastic, linear strain hardening material has been developed to study the elasto-plastic buckling of prestressed arches. The study indicates that for prestressed arches there is an interdependence between the slenderness and steepness ratios of the arch with the ratio of prestresses to the yield strength of the material, all of which control the magnitude and shape of buckling mode. While steeper arches are generally more stable in their elastic range, the effect of steepness ratio is reduced as the prestress exceeds 55% of the yield strength. Effects of loading and support conditions have also been considered. Although fixed supports result in more stable arches, their effectiveness depends on the steepness ratio and the level of prestresses. Finally, the effect of strain hardening on the plastic buckling of the arch is more pronounced for lower values of the plastic tangent modulus.

The paper describes a finite element investigation into the buckling, under uniform external pressure, of four submarine pressure hulls. Two of these hulls were traditional ring-stiffened types, but two of these hulls were in the form of corrugated circular cylinders. The latter design was based on an invention by the present author. The investigation found that the new design was structurally efficient and in the case of the smaller vessel, it was found to be structurally more efficient than the conventional design.

Another investigation, based on axisymmetric plastic buckling, was conducted on the two corrugated vessels, to determine if they were prone to collapse through the bellows' mode of failure. This investigation was carried out because former critics of this work stated that the corrugated circular cylinders would fail by the bellows' mode of failure. Neither of the two corrugated pressure hulls was found to fail through the bellows' mode of failure, thereby completely vindicating the present author. The author, however, concludes that the bellows' mode of failure can occur if the cone angles were too large.

Two of the finite element theories were based on the author's work, but the giant computer package ANSYS was also used to study non-symmetric bifurcation buckling. This work was carried out to vindicate the author's in-house computer programs, which were simpler to use than ANSYS.

Due to the increased use of composite materials in industrial applications, reliable and consistent finite element methods are required for the simulation and optimization of composite structures. In this paper, we presented the effect of finite element meshing in the modeling of degradation in composite structures under tensile stress; we have used an elastoplastic model to simulate the damage and plasticity behavior occurring in laminated composite structures carbon/epoxy: T300/914. This model works with different elements and the results obtained are not sensitive to mesh size. Thus, we have showed that two different meshes give the same results. Our findings are in good agreement compared to the experimental data.

Changes in regulation trigger changes in the innovation environments. They may block specific development trajectories, but they may simultaneously inspire and stimulate completely new openings. In this study, we look into regulation that aims to address environmental problems and facilitate creation and diffusion of sustainable technologies and processes as we examine the responses of innovators to the regulation on plastic use and production—specifically, the so-called SUP-directive. A multiple-case study comprising six companies suggests that companies manage (with) the regulation-induced innovation and needs for change by adopting three distinctive strategies: (1) proactive change orientation, (2) reactive opportunity capturing, or (3) reactive survival mode. Acknowledging that sustainability-oriented regulation may push companies with environmentally friendly innovation activities and solutions towards reactive survival mode highlights the need for managerial agility in adjusting the solutions and the ability to adopt parallel innovation strategies. Observing the strategies adopted by innovators also is informative when evaluating whether the regulation meets its profound goals and intended effects.

This research focuses on generating the plastic collapse load boundaries of a cylindrical vessel with a radial nozzle via employing three different plastic collapse load techniques. The three plastic collapse load techniques employed are the plastic work curvature (PWC) criterion, the plastic work (PW) criterion, and the twice-elastic-slope (TES) method. Mathematical based determination of plastic collapse loads is presented and employed concerning both the PWC and the PW criteria. A validation study is initially conducted on a pressurized 90-degree pipe bend structure subjected to in-plane closing bending via finite element analyses along with an elaborate explanation of the mathematical approaches for determining the plastic collapse loads via the PWC and the PW criteria. Outcomes of the validation study revealed very good outcomes for the three techniques. Accordingly, the aforementioned three techniques are utilized to determine the plastic collapse load boundaries of a pressurized cylindrical vessel/nozzle structure subjected to in-plane (IP) and out-of-plane (OP) bending loadings applied on the nozzle one at a time. The TES method revealed considerate limitations when applied within the medium to the high internal pressure spectra. It is shown that both the PWC and the PW criteria outperform the TES method in computing the plastic collapse loads. The vessel/nozzle structure revealed relatively higher plastic collapse moment boundaries under IP bending as compared to OP bending. Conclusively, methodical steps are devised for determining the plastic collapse loads via the PWC and the PW criteria for the ease of systematic application on pressurized structures in general.

In this research, 3D analysis model of air-to-air hexagonal plastic plate heat exchanger (HX) is developed numerically and compared with the available experiment. The heat transfer performances with polypropylene (PP) and aluminum (Al) indicate that PP HX can transfer heat as good as Al under this HX application. On the basis of this model, the crest length, the crest pitch and the inlet and outlet chamfer size are designed as three key parameters to improve the heat transfer performances of HX.

Background: Fast and accurate diagnosis of conditions of the hand and wrist is essential in guiding management. We aimed to analyse the predictive value of ultrasound in identifying different pathologies in the hand and wrist by correlating pre-operative ultrasound findings with per-operative surgical findings.

Methods: We retrospectively reviewed the case notes of all patients under the care of the senior author on whom a hand/wrist ultrasound had been performed between January 2007–May 2013. Of these only patients who proceeded to surgery were included as this was the correlating endpoint. Positive and negative predictive values (PPV/NPV) and sensitivity and specificity were calculated for ultrasound in identifying (i) post-repair complete tendon ruptures (versus intact repairs with scar adherence), (ii) ganglionic cysts, (iii) soft tissue masses and (iv) nerve injuries.

Results: Of 70 patients who underwent ultrasound, 36 proceeded to surgery. Fifteen patients were post traumatic and the remaining 21 were elective presentations. The median age was 38 (range 14–87) with a 1.25:1 male to female ratio. All results had a 95% confidence interval. Ultrasound had a 100% PPV for identifying post-repair complete tendon ruptures and for ganglionic cysts (sensitivities 75% and 87% respectively). Of our 6 soft tissue masses ultrasound also showed a 100% PPV. For the two nerve injury patients, PPV was 100%.

Conclusions: Our study shows that ultrasound is diagnostic for post-repair tendon ruptures and ganglionic cysts, and shows promising results for benign soft tissue masses and nerve injuries. We propose the use of ultrasound as an extension to physical examination in a dynamic clinic setting.

Changes in regulation trigger changes in the innovation environments. They may block specific development trajectories, but they may simultaneously inspire and stimulate completely new openings. In this study, we look into regulation that aims to address environmental problems and facilitate creation and diffusion of sustainable technologies and processes as we examine the responses of innovators to the regulation on plastic use and production—specifically, the so-called SUP-directive. A multiple-case study comprising six companies suggests that companies manage (with) the regulation-induced innovation and needs for change by adopting three distinctive strategies: (1) proactive change orientation, (2) reactive opportunity capturing, or (3) reactive survival mode. Acknowledging that sustainability-oriented regulation may push companies with environmentally friendly innovation activities and solutions towards reactive survival mode highlights the need for managerial agility in adjusting the solutions and the ability to adopt parallel innovation strategies. Observing the strategies adopted by innovators also is informative when evaluating whether the regulation meets its profound goals and intended effects.

Split Hopkinson Pressure Bar (SHPB) has become a frequently used technique for measuring uniaxial compressive stress-strain relationship of various engineering materials under high strain rates. The pulse shape generated in the incident bar is sensitive to the length of the striker bar. In this paper, a finite element simulation of a Split Hopkinson Pressure Bar is performed to estimate the effect of varying length of striker bar on the stress-strain relationship of a material. A series of striker bars with different lengths, from 200mm to 350mm, are employed to obtain the stress-strain response of AL6061-T6 in both simulation and experiment. A comparison is made between the experimental and the computed stress-strain curves. Finally the influence of variation of striker bar length on the sample's stress-strain response is presented.

Soil has obvious plastic characteristic. In civil engineering, some methods, such as reinforcing with natural fibres or synthetic fibres, are often adopted to strengthen soil's bearing capacity or the ability of deformation resistance. Experiences and studies indicate: length, mixture ratio, toughness and fineness of synthetic fibre have rather great influence on the strength of reinforcement soil. In order to further realize the extent of the influence and achieve relatively explicit quantization relation, taking polypropylene fibre as an example, this paper studied the impact rule of the filling quantity of polypropylene fibre (mixture ratio) on mechanical property of reinforcement soil by doing intensity experiments to plain soil and several classes of reinforcement soils with different fibre contents. As the same time, the empirical equation about soil strength varying with fibre content was established by the method of regression analysis. In the end, by simulating reinforcing status with real fibre reinforcement soil and constituting mechanical model according to various fibre contents, the variation situation of stress and strain of soil under loading was numerically simulated based on the plastic assumption about constitutive relation of soil. The study results can be generalized to engineering practice of various polypropylene fibre reinforcement soils.