Soft Impact Research Articles

Resistance of glass window subjected to high velocity soft impact

Nowadays glass as a structural material is spread use not only for buildings in form of façade, windows and columns, but as well as for the protection of displays of electronical devices, or windows used in aeroplanes. In all cases is essential to describe the behaviour of glass panels under the high velocity soft impact caused for example by bird strike, icicles impact and bumps. In this paper the aim is to describe method to estimate the resistance of glass against drop soft impact and the comparison with the real tests.

Optically Transparent Wideband Dipole and Patch External Antennas Using Metal Mesh for UHD TV Applications

The design of an external antenna for digital television (TV) has become more challenging because its relatively large size is not conformal to and esthetically preferred for commercial use. This article presents a feasibility study on external transparent antennas for ultrahigh definition (UHD) TV applications in Korea (470–771 MHz). The proposed antennas are patch and dipole types, representing directional and omnidirectional radiation, respectively. Both antennas use a metal mesh film with an optical transparency above 70% and a low sheet resistance of $0.04~\Omega $ /sq. The transparent patch using a capacitive feed has an average efficiency of 83.8% and a peak gain of 6.2 dBi, and the transparent dipole with widen arms has an average efficiency of 72.1% and a peak gain of 2.4 dBi. To emphasize the potential application to UHD TV, the average Rx peak gain of the patch and dipole antennas, which are 4.8 and 2.0 dBi, respectively, in practical conditions are investigated. The measured results of the proposed antennas offer the feasibility of implementing transparent antennas with performances identical to the nontransparent ones and a soft visual impact as an advantage, thus making them become good candidates as external antennas for UHD TV applications.

A review of hip fracture analysis subjected to impact loading

A hip fracture not only affects the body but it also the economy of human. Before improvement and prevention have been developed, research need to be done in order to identify the factors that contribute to the hip fracture. The objective of this paper is to review on past studies that related to factors that influence the impact of force to the proximal femur and to evaluate the relation of the results between computational analysis and experimental method. Experimental and finite element (FE) method is the main approaches to predict the hip fracture of the femur bone. There are several parameters of impact force such as body mass index, the thickness of soft tissue, impact velocity and stiffness of human body that influence the effect of hip fracture during fall. Based on the previous study, force and stiffness result between FE analysis and experimental have shown good correlation. For that reason, the FE method can be applied to predict future result related to the hip fracture research.

STRUCTURAL PERFORMANCE OF MODULAR WOOD PANEL OF PLANTED FOREST AND PARTICLEBOARDS BASED ON SUGARCANE BAGASSE

The production and study of alternative material produced with lignocellulosic waste to application in livestock production installation is not common in Brazil, however, is a great sustainable alternative as substitutes of conventional materials, therefore, the present study aimed to evaluate the structural performance of modular panel of homogeneous sugarcane bagasse particleboards and reforestation wood, by numerical and experimental analysis, with application prospect as lateral closure in cattle handling facilities. The evaluation of the modular panel performance was conducted by a numerical simulation by way of finite elements, in laboratory by soft body impact test, in situ, applied to a crowding pen of corral for cattle management. The results indicated good correlation among experimental and theoretical values and the modular panels met satisfactorily the proposed use as a lateral closure for cattle handling facilities.

Soft Power Potentials of European Union and Turkey: A Comparative Analysis

The purpose of this study is to analyze the soft power impact of the European Union, a supra-national body exerting its power in the economic sphere rather than in the military field such as nation states, in establishing its inspiring and appealing exceptional structure and the soft power of Turkey in a comparative perspective. For the purpose of this analysis, the soft power of the EU is examined and evaluated with a holistic approach besides dwelling on the soft power activities of the EU’s Big Four, namely Germany, United Kingdom, France and Italy. We already know that Turkey, as a candidate for EU membership, has been affected by such activities for a long time. In this respect, the point that should be inquired is how much the EU is affected from Turkey. That is why we believe that this study will shed light on the soft power and public diplomacy dimensions of EU-Turkey relations.

Experimental and numerical assessment of structural behaviour of glass balustrade subjected to soft body impact

Glass is a commonly used material in modern architecture not only for building enclosures, but also for glazed barriers preventing building occupants from falling out of balconies and different levels inside buildings. The main purpose of the balustrades is to transfer the imposed loads to the main structure of the building. That includes static loads related to the crowd pressure (horizontal line load applied at the top edge of the balustrade), but also dynamic actions produced by humans in motion. The latter is related to an accidental situation when a moving person accidentally hits the balustrade. The paper provides design principles and a review of existing standards regarding glass balustrades with a special emphasis on dynamic loads. It also presents results of an experimental campaign and numerical studies on the evaluation of the structural safety of fully-glazed balustrades subjected to soft-body impact. It includes experimental characterisation of the impactor and soft body impact tests on a glass balustrade in two states: intact and in post-failure state (with single glass ply damaged). The results of the numerical studies show good agreement with experiments in terms of displacement of the balustrade, stress in glass and acceleration of the impactor.

Does Preoperative Hypofractionated Radiation Therapy for Soft Tissue Sarcoma Impact Post-operative Wound Complications?

Standard treatment for soft tissue sarcoma (STS) includes conventionally fractionated radiotherapy at 1.8-2 Gy/fx followed by surgical resection resulting in wound complication rates of 35% (O’Sullivan et al., Lancet 2002). STS has a low α/β ratio suggesting higher doses per fraction should lead to improved tumor control with a similar side effect profile. This single arm phase 2 clinical trial assessed the safety of preoperative hypofractionated radiotherapy in patients with STS. Patients with newly diagnosed and histologically confirmed Stage I-III STS of the extremity or chest wall were enrolled on this protocol at one institution. Patients were deemed resectable with negative margins and treated with radiotherapy to 3500 cGy in 5 fractions administered every other day prior to undergoing resection 4 to 6 weeks after completion of treatment. The primary outcome was wound complications assessed using the NCIC definition. Secondary outcomes included local control, disease free survival, and overall survival. Twenty-six patients enrolled with 24 completing surgical resection. Of these patients, 14 were male and 10 female and the median age was 66. Median tumor size was 9.5 cm. The vast majority of patients had undifferentiated histology (n=11, 46%) followed by liposarcoma/leiomyosarcoma (n=6, 25%), myxofibrosarcoma (n=5, 21%), and other (n=2, 8%). Tumor anatomic location was proximal lower extremity/buttock, upper extremity, distal lower extremity, and chest wall in 71%, 13%, 8%, and 8%, respectively. Most patients presented with stage III disease (79%) followed by I (13%) and II (8%). Histologic grade was high, low, and intermediate in 79%, 13%, and 8%, respectively. Two patients (8.3%) had positive margins on surgical specimens and plastic surgery was involved in 9 of the operations (38%). Median RT elapsed days was 9.5 and the median time from initiation of RT to time of surgery was 50.5 days. At a median follow-up time of 19.8 months, 6 patients (25%) experienced a post-operative wound complication. Local control was 100%. Five patients developed distant metastatic disease (20.8%) with a median time to distant metastases of 15.4 months. Two patients (8%) died of metastatic disease. Results of preoperative hypofractionated radiotherapy for treatment of patients with STS of the extremity and trunk demonstrates post-operative wound complication rates comparable to historical rates using conventionally fractionated RT. Although local control was optimal at 100%, further follow-up is needed to corroborate these findings.

Similarity index: A procedure for comparing impact time histories validated with soft impact test

This paper describes the procedure developed to compare the dynamic behavior of a structure due to an impact load. The comparison procedure is especially useful for controlling the impact level and repeatability during testing, but it can also be used for fine-tuning the process of simplified models or finite element models. Both features provide important engineering value and permit the assessment of transient impact histories, qualitatively and quantitatively. More than 240 soft impacts, from a human impact against glass test campaign, have been used to develop and validate the comparison method.Three indicators have been defined in order to control the most significant impact parameters: the impact level (impulse), duration of the impact (stiffness), and maximum acceleration (peak system response). Based on the knowledge of the impact phenomena, the procedure defines a Similarity Index (SIn) that entails the weighted addition of the indicators. The SIn procedure assigns a numerical value to the difference between two time histories over the duration of the contact, and it is used to compare a series of data from a database of soft human impacts tests versus standard glass curves and curves obtained from a simplified 2DOF model.

Temperature-tunable time-dependent snapping of viscoelastic metastructures with snap-through instabilities

3D-printed metastructures and metamaterials with snap-through instabilities have been extensively investigated in recent years. However, most of the previous research has been limited to the analysis of their elastic response. This paper focuses on the time-dependent mechanics of 3D-printed viscoelastic metastructures with snap-through instabilities. Due to viscoelastic relaxation, a regime called pseudo-bistability can be observed: a previously deformed 3D-printed metastructure can appear to be temporarily bistable before snapping back to its undeformed configuration after a critical time. Experiments with 3D-printed samples and finite element simulations demonstrate that the critical time can be tuned by adjusting the temperature. While the time-dependent snapping causes a change in the overall height in the case of single layer metastructure, experimental and finite element results show that the same type of time-dependent snapping can also be used to obtain an internal reconfiguration when the overall height of a multilayer metastructure is constrained to remain constant. Because of the possibility of tuning the critical time for a given sample by varying the external temperature, harnessing the pseudo-bistable mechanics of these viscoelastic metastructures gives new opportunities towards the development of novel reconfigurable metastructures with programmable response and properties for applications in soft robotics or impact protection.

Performance assessment of long‐range and Sigfox protocols with mobility support

SummaryLow‐power wide area networks (LP‐WANs) protocols are considered options to meet the requirements of Internet of Things (IoT) solutions that need long‐range communication with low power consumption. Few studies intended to evaluate the performance of the same class of protocols coexisting in the same environment and with mobility support. This paper explores the technical characteristics of Sigfox and long‐range (LoRa) protocols and presents a performance evaluation study considering mobility scenarios. The experiments were performed in real environments. Then, two prototypes for LoRa and Sigfox equipped with Global Positioning System (GPS) were created. Quantitative and qualitative performance metrics were also proposed for this study. The results showed that the coexistence between these protocols has soft impact on the performance presented. Because of the movement, the effects of Doppler, multipath, and signal fading hardly affect the performance of both protocols.

Soft body impact resistance of composite foam core sandwich panels with unidirectional corrugated and tubular reinforcements

Bird strikes represent a major hazard in the lifecycle of composite aircraft components, due to the low impact resistance of composites. The research presented in this paper investigates soft body impact performance of composite sandwich panels with corrugated and tubular core reinforcements. This type of panel with augmented strength and stiffness in one direction is of high importance for specific aerospace applications. The panels were subjected to high velocity impact with soft gelatine projectile as used in bird strike tests. In addition, the experimental part included non-destructive inspections of the sandwich panel samples. Panel performance was also analysed with the non-linear transient analysis software LS-DYNA with finite element and SPH capability. The panel with corrugated reinforcement showed good impact resistance with damage restricted to the impacted face sheet, foam core and corrugated reinforcement. The panel with tubular reinforcement, of the same thickness, did not suffer any damage at the same impact velocity of 115 m/s, but was damaged at a higher impact velocity of 235 m/s. The numerical studies helped to understand the experimental data, enabling comparison of impact performance of the reinforced sandwich panels and a benchmark conventional sandwich panel. The proposed reinforced sandwich panels, with the desired augmented strength and stiffness in one direction, showed improved impact resistance in comparison to conventional sandwich panels and therefore have potential for application in aerospace structures where these properties are desirable.

Maintaining a Normal Level of Plasma Bioregulators on the Background of Daily Wearing Corrective Underwear in Women with Developing Gynoid Obesity

In modern society, obesity in women in developed countries retains its widespread prevalence. Much attention to this problem is caused by the current increase in the number of cases of obesity among middle-aged women who are not able to regularly experience muscular loads in the form of exercises and comply with various dietary restrictions. In this regard, there is a need for cosmetic correction of their figure in the presence of minimal effort on the part of women with signs of obesity. The solution to this problem may be the wearing of corrective clothing, which is able to effectively reduce the volume dimensions of the body through a soft mechanical impact on it in problem areas. In the work carried out, the safety assessment of the long wearing of the author's version of the trousers was carried out taking into account the dynamics of the plasma level of functionally significant hemostasis biregulators for half a year. It was found that women with obesity 1 degree, wearing corrective clothing, there was a persistent preservation of the indicators taken into account within the normal range. The great advantage of using the author's version of corrective clothing for women with obesity was the upcoming visual reduction of their body sizes in the area of ​​application of the product. At the same time, all women under observation maintained a consistently normal plasma level of hemostasis regulators corresponding to the control values. The results obtained allow us to consider the author's corrective clothing as a complete and safe component of the visual correction of the manifestations of developing obesity in women.

Three-dimensional map for a piecewise-linear capsule system with bidirectional drifts

Abstract A three-dimensional map is studied in this paper to provide a fundamental understanding for the vibro-impact capsule system, which is a non-autonomous two degrees-of-freedom non-smooth dynamical system consisting of soft impact and dry friction with forward and backward drifts. By using the map, one can investigate the global and local dynamics of the system and construct all possible local mappings for a wide range of parameter variation. An example study by varying the amplitude of external excitation of the system is presented. Our results show that the proposed map can effectively explain the occurrence of the boundary-intersection crossing and the sliding bifurcations observed in the system.

Experimental and numerical investigation of high velocity soft impact loading on aircraft materials

Bird strike on aircraft remains a serious threat to flight safety. Experimental investigations employing real birds are associated with high cost and low reproducibility. Therefore, physical substitute materials are often used instead of real birds. This study investigates the soft impact loading on aluminium and laminated glass targets from ballistic gelatine and rubber projectiles. The two targets simulate strike on the aircrafts' fuselage and windshield respectively. The full field out of plane displacements of the targets were recorded for velocities 110 to 170 ms−1 using digital image correlation during gas gun experiments. A simulation model based on Smoothed Particle Hydrodynamics was developed and validated against the experimental data from all four projectile-target material combinations. It was shown that for the same momentum, a rubber projectile exerts a higher pressure on a target as compared to gelatine, even though the out of plane displacements and in-plane strains are similar. This led to fractures in the impacted laminated glass when rubber was used. The study offers new experimental data as well as efficient design modelling tools to mitigate damage imposed during bird strike. The models provide a way towards enabling the optimisation of real, large scale aircraft structures and components.

Recycled gypsum block: development and performance

Abstract The gypsum plaster waste is still faced a serious economic and environmental problem. Considering the high volume and the destination often inadequate. Intending to provide a mitigating alternative, this research intends to develop blocks that incorporate the industrial gypsum plaster waste through reverse logistics. For this, a physic-chemical recycling process of gypsum plaster waste was carried out on an industrial scale and the developed material was characterized in anhydrous and fresh state. Then, blocks were made with the recycled material and characterized according to NBR 16495 (ABNT, 2016). After its characterization, the material was evaluated for its mechanical performance when used in walls, regarding the tests of suspended vertical loads and hard and soft body impact, according to the guidelines included in the performance standard NBR 15575-4 (ABNT, 2013). The walls constituted with the developed material showed satisfactory performance, having, in some cases, presented superior performance in comparison to the conventional walls of gypsum blocks, according to results presented by the Technical Assessments Document - DATEC nº 27 (2015). Finally, small walls of the recycled gypsum block and gypsum glue were elaborated to verify the compressive behavior. Regarding these verifications, it was noticed that the small walls obtained good resistive capacity.

Computer science and engineering: utilizing action research and lesson study

ABSTRACTThis article explores one group’s use of action research (AR) and lesson study in three US university-level computer science courses affecting 85 undergraduate computer science and engineering students. It offers an overview of three areas including AR, lesson study, and engineering soft skills. The research group identified a problem: undergraduate engineering student soft skill understanding. The group collaborated to enhance participant engagement with this problem by utilizing one lesson focused on soft skills over three research lesson iterations in three distinct university semesters (2017-2018). Field notes were the main data collection method. Observational field notes were recorded in the three research lesson iterations, and themes from the notes were identified. The group valued peer interactions, and the research lesson adaptations as well as pedagogical changes were based on evidence. Four themes were identified, and participant comments were considered as the lessons became more focused . The research group argues that AR and lesson study are separate and distinct ventures based on this yearlong experience, which is counter to some other literature presented. Implications are large for all stakeholders interested in AR, lesson study, soft skill utilization, conflict management, and participant learning impact. Possibilities for enhanced participant engagement exists with honed lesson pedagogy.

Energy absorption of aluminum panels subjected to gelatin projectile impact

Abstract Digital image correlation (DIC) method has been widely used on dynamical experiments. This full-field and real-time method can fill in the gap of traditional point-based measurements of typical structures subjected to soft body impact such as bird strike. In order to get further understandings of soft body impact process, the present study analyzed the time-dependent energy exchange during impact experiments. The dynamic responses of the aluminum target panels were obtained using 3D digital image correlation method so that their displacement and strain field histories can be tracked. By introducing the material properties of the targets, their time-dependent stress state and consequently the strain energy can be calculated. With the help of time-dependent profiles of target panels, their energy absorption properties were theoretically analyzed, including the exchange of kinetic energy and plastic work. The results showed that when the impact loadings were increased, the plastic work generated by radial membrane force became the major source of energy dissipation. The transverse movements consumed more kinetic energies than rotatory moments. This research may provide a further application of DIC results and help to better understand the soft body impact process on targets with large deformations.

Effect of Method Type on the Response of Continuum Vibro‐Impact

The force integration method (FIM) and the methods based on the mode transfer principle are the frequently used choices for solving the vibro‐impact problem of continuum. Notably, there are different solving options such as numerical and semianalytical procedures. In this paper, a new modeling method based on the mode transfer principle, called the relative mode transfer method (RMTM), is proposed, and its semianalytical solution is obtained. A typical vibro‐impact problem of continuum beam is studied. The time‐history response under periodic excitation is obtained using the FIM, mode transfer method (MTM) through numerical procedure, and the RMTM through numerical procedure and semianalytical procedure. The effects of the method on the system steady‐state response, amplitude‐frequency response, and sticking motion are discussed. The impact type is divided into “hard impact” and “soft impact” when obtaining the results.

Experimental and numerical studies on the behaviour of fibre-reinforced composites subjected to soft impact loading

This paper presents detailed experimental and numerical studies on the behaviour of composite laminates subject to impact loading by soft objectives. In this research, gas-gun experiments employ woven carbon fibre reinforced poly (ether-ether ketone) (CF/PEEK) and gelatine projectiles to study the response of composite laminates under soft impact loading. A high-speed camera is employed to capture the deformation of the projectiles and a three-dimensional (3D) Digital Image Correlation (DIC) system is used to record the deformation of the impacted composite specimens. A numerical finite-element (FE) model, in which Hashin’s theory is employed for composite modelling and Smooth Particle Hydrodynamics (SPH) method is used for modelling the gelatine projectile and is developed to simulate the soft impact on the composite laminates. The capability of the developed model is validated using the gas-gun experimental results. Good agreement has been shown between the predictions from using the FE model and the experimental results.

Environmental safety of green construction and requirements of urban planning legislation

The vector that defines the strategy of innovative development of the construction industry in Russia consists in providing conditions for increasing labor productivity, reducing energy intensity and prime cost of construction process by means of introducing new institutional mechanisms that allow directing the development of the construction complex to the implementation of green construction (ecological construction) investment projects. Today, the conditions for performing green construction as an innovative and energy-efficient solution of environmental management problems are being provided in Russia taking into account modern environmental requirements. The article discusses some problems and issues of green construction, considering architecture and construction areas that are aimed at erection and operation of buildings with soft impact on the nature. In order to ensure environmental safety, the effectiveness of elaboration and implementation of investment projects for green construction should be substantiated taking into account the ecological-and-economic model of the life cycle based on the subject-oriented approach. The present scientific article defines the state and trend of green construction development in the investment-and-construction sector, analyzes environmental safety and methods of creating the innovative green building development platform. The authors recommend developing a methodological outfit to optimize the interaction of economic entities of green construction. The optimization will help to assess the effectiveness of improving the innovative green building platform and the level of environmental safety.