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Fragments and blast waves generated by explosions pose a serious threat to protective structures. Experiments have shown that the single ballistic resistance or blast resistance of the steel plate improves significantly after coating polyurea. However, the dynamic response and structural design for the polyurea-coated structure under the combined fragments and blast loading are still lacking. In this paper, the impact resistance of polyurea-coated steel plate under complex dynamic loading is analyzed and designed for improving comprehensive ballistic and blast resistance using the newly established computational evaluating model. Firstly, according to the thickness and placement effects of the coating on the ballistic and blast resistance, the steel-core sandwich plates are designed, which are proved to own outstanding comprehensive ballistic and blast resistance. Besides, the distribution diagram of ballistic and blast resistance for different polyurea-coated steel plates is given to guide the design of protective structures applying in different explosion scenarios. Furthermore, the dynamic response of designed plates under two scenarios with combined fragments and blast loading is studied. The results show that the synergistic effect of the combined loading is significant. It reduces both the ballistic and blast resistance of the polyurea-coated steel plate and causes a more severe failure than the sum of the failures induced by the individual fragments and blast impact. Besides, the acting sequence of the fragments and blast affects the structural protective performance heavily. It is found that the first loading inducing structural large deformation or damage generally is dominant. In the scenario of fragments penetrating firstly, the excellent unit-thickness ballistic performance of the structural front part is strongly needed for improving the comprehensive ballistic and blast resistance. The analysis of dynamic response and structural design for the polyurea-coated steel plate in this paper will be helpful for designing lightweight protection structures with excellent comprehensive ballistic and blast resistance.

The development of new building materials, able of absorbing more energy is an active research area. Engineering Cementitious Composite (ECC) is a class of super-elastic fiber-reinforced cement composites characterized by high ductility and tight crack width control. The use of bendable concrete produced from Portland Limestone Cement (PLC) may lead to an interest in new concrete mixes. Impact results of bendable concrete reinforced with steel mesh and polymer fibers will provide data for the use of this concrete in areas subject to impact loading. The experimental part consisted of compressive strength and impact resistance tests along with a result comparison with unreinforced concrete. Concrete samples, with dimensions of 100×100×100mm (cubes), and 500×500×50mm (slabs), were poured and were treated at ages of 28, 56, and 90 days. The compressive strength increased by 36.11%, 45.5%, and 52.4% respectively, whereas the impact resistance for samples reinforced with steel mesh and polypropylene fibers gave superior results to the conventional mixes.

Incorporation of hollow fibers in polymer base composites has gained great interest due to their flexibility and lightweight structure. Among many research studies on this subject, the mechanical performance of polyester hollow fiber/E-glass reinforced polymer composites has not been investigated. The main objective of the present work was to investigate the fracture toughness and impact resistance of E-glass/epoxy composites hybridized by a separate layer of polyethylene terephthalate hollow fibers (PETHFs). The samples were prepared by placing a layer of PETHFs in different contents (0, 0.23, 1.18, or 2 wt.%) and in two different forms of filaments (PETHF-FIs) or staple fibers (PETHF-STs) between two layers of biaxial or triaxial E-glass fabrics. The mechanical behaviors of the samples were investigated by performing a set of tensile and impact tests. Scanning Electron Microscopy (SEM) and Field Emission Scanning Microscopy (FESEM) were also used to evaluate the surface morphologies of the hollow fibers and the fractured samples. The results revealed that, unlike PETHF-FIs, PETHF-STs could weaken the mechanical performance of the pristine E-glass/epoxy composites. The internal channel blockage of PETHF-STs was observed in the FESEM images of the fractured PETHF-STs hybrid samples. The highest toughening effects were observed with incorporation of 1.18 wt.% PETHF-FIs in biaxial E-glass/Epoxy composites and 2 wt.% PETHF-FIs in triaxial E-glass/Epoxy composites. The highest value of impact resistance belonged to the samples hybridized with 2 wt.% of PETHF-FIs. Crack deflection, fiber pull out, and fiber stretching were the predominant fracture mechanisms observed in the PETHF-FIs hybrid composites.

By using novel radial non-crimp fabrics made of carbon fibers, higher-performance thin brake discs or other friction elements made of Ceramic Matrix Composites can be produced. This is made possible by industrial preforming using needling technology, rapid chemical vapor infiltration and liquid silicone infiltration. In addition to density reduction, wear and impact resistance are to be improved.

A multiscale approach is used here to investigate the impact properties of carbon fibre/carbon nanotube-reinforced polymer. For this purpose, the mechanical properties of the carbon nanotubes (CNTs) are obtained by molecular dynamics simulations. Then, they are included in the polyethene matrix, and the mechanical properties of CNT-reinforced polyethene are computed using a stochastic approach. Considering the CNT-reinforced polyethene as the matrix, the effect of adding the carbon fibres on its mechanical properties is investigated in the next step. Finally, utilizing a stochastic method, the macro-scale mechanical properties of carbon fibre/carbon nanotube-reinforced polymer are computed. Thereafter, the impact test is applied on the models. The finite element method is used to investigate the mechanical and impact properties of representative volume elements. The effects of waviness, volume percentage and aspect ratio of the carbon fibre and CNT on the mechanical properties of the multiscale composite are evaluated. It is shown that reinforcing the polyethene matrix by carbon fibres and CNTs significantly increases its impact resistance. Adding 3% and 5% volume percentages of CNT into 3%-carbon fibre/polyethene and 5%-carbon fibre/polyethene respectively, resulted in 26% and 47% improvement in the impact resistance of the composite.

Reinforcing thermoplastic polymers with natural fibres tends to improve tensile and flexural strength but adversely affect elongation and impact strength. This limits the application of such composites where toughness is a major criterion. In the present work, bamboo fibre reinforced polypropylene (PP) composites were prepared with bamboo fibre content varying from 30% to 50% with improved impact resistance. Homopolymer and copolymer PP were used as the matrix polymer and an elastomer was used (10% by wt.) as an additive in the formulation. Copolymer based composites exhibited superior elongation and impact strength as compared to homopolymer based composites. The adverse impact of elastomer on tensile and flexural strength was more pronounced in homopolymer based composites. The study suggested that the properties of the bamboo composites can be tailored to suit different applications by varying reinforcement and elastomer percentage.

This investigation aims to study the abrasion and impact resistance of fibre-reinforced concrete before and after exposure to salt scaling. Different types of steel fibre and different mixture compositions were used to improve the strength and resistance of the tested mixtures. The variables were the type of steel fibres, surface condition of steel fibres (coated and uncoated), length of steel fibres (35 and 60 mm), volume of steel fibres in the mixture (0, 0·35 and 1%), end condition of steel fibres (single- and double-hooked ends), coarse aggregate size (10 and 20 mm), coarse aggregate/fine aggregate ratio (0·7 and 2) and cement content (300 and 550 kg/m3). The results indicated that the uncoated steel fibres experienced some rust after the exposure to salt scaling, causing more deterioration and higher surface scaling than coated steel fibres. The results also revealed that the samples that were exposed to salt scaling showed a noticeable reduction in the abrasion and impact resistance compared with samples that were not exposed to salt scaling. Adding steel fibres, however, alleviated this reduction and contributed to enhancing the impact and abrasion resistance of scaled concrete surfaces.

The demand for light-weight materials, exhibiting superior strength and higher toughness, has increased attention to cryogenic temperature rolling as it produces bi-modal microstructures with improved mechanical properties. The samples were cryorolled to a final thickness of 1 mm after thickness reductions of 50%, 66.66%, 75%, and 80%. The ballistic behavior of cryorolled AA 6082 aluminum alloy with different rolling strains/thickness reductions was investigated in this study. The cryorolled Al alloys were subjected to normal high-speed impact using dome-shaped projectiles at velocities between 50 and 250 m/s. The 66.66% thickness reduced samples exhibited higher impact resistance, especially at higher impact velocities. The maximum energy absorption of 106.43 J was observed for 66.66% thickness reduced sample at an impact velocity of 234.38 m/s. This study suggests the existence of an optimal value of cryogenic rolling strain for superior impact resistance, possibly due to an ideal combination of coarse and fine grains in the resulting bimodal microstructure.

This paper aims to present a new sandwich structure comprising of a grid hemp core and carbon skins. Two typology of hemp cores (7 and 8 mm in thickness) that mainly differ in the density values (0.36 and 0.63 g/cm3) were produced by an ad hoc manufacturing process and adopted to produce the sandwich structures under investigation. Aiming to extend the use of natural fibre composites (NFCs) for applications where high impact resistance is required and to replace common materials used as cores with more eco-friendly ones like the proposed hemp core, low velocity impact (LVI) tests and non-destructive (ND) tests were carried out.

Polycarbonate (PC) is a widely used amorphous polymer. Among its many interesting properties, we can mention, among others, transparency, impact resistance and low density. However, long exposure to temperature changes its physicochemical, thermal and mechanical properties. The aim of this study is to reveal the effect of the time of exposure to temperature, in air, on the properties of the PC. Thus, maintaining this material at 80 °C causes damage as revealed by Fourier transform infrared spectroscopy (FTIR) and microstructural observations by scanning electron microscopy (SEM). The thermal analyzes also made it possible to observe modifications of the molecular chains as well as modifications of the mechanical properties confirmed by mechanical tests.

Thanks to their mechanical properties and lightness, composite materials, are widely used as structural parts in marine, automotive and aerospace. However, even though they are characterised by high in-plane properties, their out of plane performances are not remarkable, therefore during operating conditions, they can be involved in accidental impacts by runaway debris or tool drop in maintenance operations that can cause barely visible impact damage (BVID). This type of damage is usually related to a particular category of impact events defined as Low Velocity Impact (LVI), characterised by velocities up to 10 m/s [1] . In order to overcome the aforementioned low impact resistance of composites, research is focused on improving the damage tolerance of this class of materials. One solution proposed in literature is the hybridisation process that merges synthetic and natural fibres aiming to obtain a composite with good in-plane and out-of-plane properties [2] , [3] , improving impact performance while guaranteeing resistance and stiffness due to the higher modulus of the synthetic fibres. The aim of this work is to evaluate the impact behaviour of Hemp-Carbon composite panels manufactured by hybridisation, under LVI events. Damping tests and low velocity impact tests at 10 J and 20 J were carried out in order to evaluate the Hybrid configuration damping properties and impact behaviour. Moreover, in order to have a better understanding of the internal damage for each impact energy, non-destructive analyses were performed. Results showed improved damping properties for the Hybrid configuration, which is characterised by a more ductile behaviour if compared to traditional Carbon fibre reinforced polymers (CFRP). Non-destructive tests carried on the Hybrid composite showed, at the same absorbed energy level, a smaller extension of the damaged area (−40% at 10 J and −10% at 20 J) localised at the interface between hemp and carbon fibres.

The mechanical properties of mechanically recycled polyethylene (rPE) were studiedin relation to the composition of the feedstock. This composition varied in six stepsfrom only bottle bodies from a single type of high-density polyethylene (HDPE) tothe complete composition of an industrially sorted polyethylene (PE) product,including other packaging components, other PE-based packages, sorting faults andresidual waste. The rPE with the highest impact resistance was made from the single-grade bottle bodies. The addition of bodies made from other types of PE alreadyreduced the impact resistance with 11%. All the other stepwise additions ofpackaging components and faultily sorted objects caused the impact resistance todecrease further. Conversely, the elongation at break grew with the stepwiseaddition of these packaging components and faultily sorted objects. From the usedmethods, the best analysis method to accurately determine the polymericcomposition of the rPE was found to be near-infrared-assisted flake analysis. Thismethod can not only be used to determine the polymeric composition, but due to thestrong correlation with the impact resistance, it is also a valuable indicator for theexpected mechanical properties of rPE.

This article deals with initial material selection and design method of long fibre-reinforced thermoplastic (LFT) based on impact resistance requirements. In this study, effects of material propert...

Among the various polymer fibers available, polypropylene (PP) fibers are often used to improve the impermeability, impact resistance, anti-wear and crack resistance of concrete. In order to improv...

The development of self-compacting concrete using alternative materials is expanding in recent years due to the technical and economic benefits of the mixture. This study focuses on the structural and compositional behavior of sodium hydroxide (NaOH)-activated fly ash based self-compacting concrete (SCC). Fly ash was partially replaced with Ordinary Portland Cement from 0–30%. The tests performed on concrete samples include workability, strength, microstructural, and impact resistance. The results showed that activated fly ash reduces the heat of the hydration process of the concrete mixture but enhances pozzolanic reactions, which led to increased strength properties. The addition of activated fly ash modifies the mineralogy of the concrete, as evident in strength characteristics. The best performance of the activated fly ash based SCC, in terms of strength, was found at 10–15% substitutions, which can somewhat reduce the cost of production of SCC and strength improvement advantage.

Cracks in polymers can be healed by endowing materials with self-healing performance. Cracks in epoxy resins containing thermo-reversible Diels–Alder bonds (EP-DA) can be self-healed via different heat treatments. However, EP-DA exhibits the disadvantages of brittleness and poor impact resistance yet as that existed in the common epoxy resins, and which limits the application of thermo-reversible self-healing epoxy resins. Herein, thermoplastic polyurethane (TPU) was introduced into EP-DA for the purpose of reducing the brittleness and improving the impact resistance of EP-DA. Meanwhile, it was expected that the self-healing performance of EP-DA could not be affected evidently. Results showed that the impact resistance of EP-DA had been improved greatly as expected upon TPU modification. More importantly, instead of affecting the self-healing performance of EP-DA, the self-healing speed of EP-DA was accelerated evidently by the incorporation of TPU. On the other hand, the healing efficiency of EP-DA was also enhanced markedly. In fact, TPU-modified EP-DA was repaired by dual actions of thermo-reversible DA reaction and thermal movement of thermoplastic polymer chains. In addition, TPU-modified EP-DA could also be healed for many damage-repair cycles. Therefore, thermoplastic polyurethane played a triple role as toughening, accelerating and enhancing self-healing performance of thermo-reversible epoxy resins. Thermoplastic polyurethane (TPU) was introduced into thermo-reversible self-healing epoxy resins (EP-DA) successfully. As a result, the brittleness was reduced and the impact resistance of EP-DA was improved greatly. What’s more, instead of affecting the self-healing performance of EP-DA, the self-healing speed of EP-DA was accelerated evidently while the self-healing efficiency of EP-DA was enhanced markedly. Therefore, TPU played a triple role as toughening, accelerating and enhancing self-healing performance of thermo-reversible epoxy resins.

Impact resistance of a material is of utmost significance in many essential structural applications. But, concrete is weak in withstanding impact/collision/blast loads. Addition of crumb rubber as a replacement of mineral aggregates has yielded a material which has high impact resistance and is termed as rubcrete. It has been observed that 0–20% replacement of fine aggregates with crumb rubber produces rubcrete with high energy absorption capacity. But, rubcrete is usually associated with a reduction in strength. Pretreatment of crumb rubber particles and grading them in the same proportion as that of the fine aggregates will help to mitigate the reduction in strength. Addition of steel and polypropylene fibres aids in maintaining the strength characteristics of rubcrete and facilitates control in the generation and propagation of cracks. Improved energy absorption characteristics were observed for steel and polypropylene fibre contents up to 1% and 0.3%, respectively. In order to determine the optimum proportions of crumb rubber, steel fibres and polypropylene fibres, the energy absorption capacity of prisms of size 100 × 100 × 500 mm was evaluated. Results show that 15% of crumb rubber, 0.75% of steel fibres and 0.2% of polypropylene fibres were the ideal proportions of crumb rubber, steel fibres and polypropylene fibres, respectively, to attain maximum energy absorption/cost ratio. This paper presents the results of numerical and experimental studies conducted on the impact behaviour of M 40 and M 60 grade ordinary concretes, rubcrete and fibre-reinforced rubcrete beams of dimensions 100 × 150 × 1200 mm. Durability studies were also carried out on fibre-reinforced rubcrete mixes to ascertain their behaviour in extreme environments. From the durability studies, it was noticed that when exposed to severe environments, fibre-reinforced rubcrete specimen had comparable properties with that of ordinary concrete.

Recently, the incorporation of several different types of fibers into a single matrix has led to the development of superior hybrid composite properties at a cheaper cost. Fiber hybridization is one of the active strategies to toughen composites and improve impact damage resistance. However, the extraordinary high strength and stiffness of the carbon fiber as well as its lower damage tolerance make it more susceptible under the impact loading. This article mainly aims to improve impact damage resistance of carbon fiber pipes through fiber hybridization strategy with glass fibers under low-velocity impact. The composite pipes reinforced with thin internal liner of high-density polyethylene were fabricated through filament winding technology. Eight pipe configurations with different stacking sequences and fiber content ratios with a constant winding angle of [Formula: see text] were fabricated and tested under impact energies, 50 and 100 J. The damage characterization was evaluated using the optical imaging and mechanical micrograph sectioning technique. Results indicate that the hybrid configurations showed better energy absorption than reference carbon fibers specimen under 50 J impact energy. Specifically, specimens with glass fibers on the exterior side and alternative configuration of carbon–glass fibers showed better impact resistance with less damage observed. Meanwhile, the specimens with glass fiber on the exterior side suffered from extreme damage with increase in the energy absorption and maximum displacement for both fiber content ratios under 100 J of impact energy.

Advanced composite materials reinforced with high-performance fibers like carbon, glass, aramid, or ultra-high-molecular-weight polyethylene are widely used as lightweight materials in the fields of automotive, aerospace, sports, and protection. However, nearly always these composites are opaque and/or absorb light, which greatly limits their application in areas where high optical transparency is desired such as impact-resistant windows and visors. In this work, composite laminates that combine high optical clarity with high mechanical properties are reported for the first time using highly oriented high-density polyethylene (HDPE) films as the reinforcing phase. A high optical transparency with a far-field light transmittance of around 85% was achieved for four-layer HDPE-reinforced laminates sandwiched between glass or polycarbonate (PC) sheets with either unidirectional (UD) or bidirectional (BD) orientations. In combination with outer layers of glass or PC, the fabricated transparent composite laminates show high tensile strength and also high penetration energy absorption, outperforming existing transparent materials like glass, laminated glass, or PC. These transparent composites combine both high mechanical performance and high optical clarity, providing great potential for future applications in structural glazing, automotive glazing, safety shields, visors, and displays for portable electronics.

Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. Aim of this paper is to describe the method of dynamic impact testing and the novel concepts of evaluation of the impact test results, such as the impact resistance and the impact deformation rate. All of the presented results were obtained by testing two W-B-C coatings with different C/W ratio. Different impact test results are discussed with respect to the coatings microstructure, the chemical and phase composition, and the mechanical properties. It is shown that coating adhesion to the HSS substrate played a crucial role in the coatings’ impact lifetime.

This paper intends to study the mechanical characteristics of self-compacting concrete (SCC) containing polypropylene fibres (PPF). 99 SCC specimens containing PPF were manufactured and tested. White 12-mm long PPF were used at 0%, 0.1%, and 0.3% by volume. The slump flow and T 500 were obtained on fresh SCC, while compressive strength, splitting tensile strength, impact resistance and heat resistance tests were performed to evaluate the SCC performance in the hardened state. To determine the effect of heat on SCC with and without PPF, the compressive and splitting tensile strengths of 28-day specimens placed at 250 °C for 8 h in an oven were evaluated. For the impact test, 50 mm, 100 mm and 300 mm cubic specimens were used. Also, a correlation was determined by trial and error to relate impact resistance with compressive strength, tensile strength, concrete age, temperature and PPF content. The results showed that, by increasing the volume of fibres in SCC, dispersion decreased. It was also observed that the use of 0.1% PPF significantly enhanced the compressive strength of SCC. Furthermore, the best performance in the splitting tensile strength, impact resistance and heat resistance tests was attained at 0.3% PPF.

Ring-opening metathesis polymerization (ROMP) produced homopolymers and copolymers of 5-ethylidene-2-norbornene (ENB) and 5-methanol-2-norbornene (NBOH), and this provided a platform to explore the...

The application of composite materials is an important measure to reduce the automotive wheel’s weight. In order to ensure the safety of passengers, the wheels must pass a series of tests including...

Phase formation, impact resistance, and fracture surface were investigated in unreinforced Al6061, Al6061-5wt% fly ash and Al6061 hybrid composites containing 5wt% fly ash and 1,3 wt% CaO. The Al6061 composites were fabricated the stir casting process. The XRD patterns reveal the formation of second phases (MgAl2O4, CaAl4O7 and MgSiO3), which were found in the Al6061 hybrid composites. The average grain size of Al6061 hybrid composite are much smaller than that of unreinforced Al6061.The impact resistance was enhanced by approximately 67% in Al6061 hybrid composite as compared to unreinforced Al6061 alloy. Brittle fracture indicting brittle fracture was observed in unreinforced Al6061 alloy while evidence of a mixture of brittle and ductile fracture was found in the Al6061 hybrid composites.

The present study reports on the influence of printing process parameters, architecture, raster, infill orientation and filling on the density, macrostructure, and mechanical properties, including impact resistance, of biodegradable polymer parts fabricated in polylactide (PLA) on a desktop printer. It complements and considers phenomenologically the results of recently published similar studies, including the use of recycled filament. In our study, complex mechanical properties for the samples printed at the same time on a Replicator 2 printer were investigated. Three samples were printed for each test. Full mechanical characteristics (tensile, compression and bend strengths and impact resistance) of the printed PLA material are reported. This is the novelty in comparison to other studies, where the samples test were printed individually or in a series for each test. The shape and thickness of the layered macrostructure, the presence of holes inside the layers, the number of shell perimeters and the fill density all influenced the tensile properties of the printed materials. These results show the possibility of printing with a 0.3, i.e. shorter printing time than 0.1, 0.15 and 0.18 mm layer thicknesses also reported, without significant decrease in mechanical properties. It is interesting to note that the compressive strengths, the yield of 70–80 MPa and a UTS 113–120 MPa for the printed material with a fill density of 94–96% are comparable with those of aluminum.

The aim of the study was the evaluation of properties of variously composed composite materials based onpolyurethane filled with tea tree oil (TTO) and addition of other ingredients. The tea tree oil/cyclodextrin inclusioncomplex was prepared by using the ‘Paste method’ described in Shrestha, M and others. (2017) (Shrestha et al. 2017). Toanalyse the properties of composite materials following testing methods were conducted: density, tensile strength,compression test, impact resistance. In the study, pursued in the Lodz University of Technology in Poland, thirteenmaterials with different percentile content of additives: TTO/β-CD, propolis, TTO/β-CD/Propolis, TTO were preparedand tested to establish the most favourable characteristics. Properties of sample containing Tea tree oil/ β-cyclodextrin/Propolis were the most satisfying and were assumed to be accurate in fulfilling the role of the hoof crackfiller the best in the first study. With the higher amount of the additive the mechanical properties weakened preventingthe use of the product in the hoof cracks.

The aim of the study was to compare the physical and mechanical properties of known prostheses for cranioplasty: knitted Codubix based on polypropylene and Modela-cryl resin based on PMMA. It was expected that the study would allow to check whether it is possible to combine their properties, which should enable the preparation of a new material with properties combining the best features of both components. Physico-chemical and mechanical properties were evaluated. It was found that the two materials meet the requirements for chemical purity, ensuring the safety of their use. Regarding the mechanical properties, the energy of impact diffusion for two types of prostheses was determined applying the Drop Tower technique. The polymerisation heat of Modela-cryl resin was determined in real time using the DSC technique.

The article addresses the issue related to the disposal of dust from steel industry as a reinforcing filler for epoxy composites. The polymer composition of "cold welding" that has been developed and studied includes epoxy dian oligomer, amine hardener and the filler – finely dispersed waste of metals. Polyethylene polyamine was used as a hardener in order to improve heat resistance and strength characteristics. Manganese triacetate was used in order to decrease the temperature and reduce the time of curing. The possibility was established to dispose of finely dispersed metal-containing waste from metallurgical production to be used a filler for epoxy composites of cold curing. It was revealed that the optimal content of dusts from foundries in the composite is at the level of 45–60 %. At this content, there is the highest impact resistance at the level of 40–50 MPa and a softening temperature in the range of 170–190 °С. It was established that at an increase in the amount of a filler from 40 % to 70 %, the cross-linking degree increases by 88 % to 98 %, respectively. However, at the content of the filler less than 45 % or exceeding 60 %, the impact resistance of the resulting composites decreases. At the content of a filler in the composite less than 45 %, the cause of low values of impact resistance and softening temperature could be the low cross-linking degree, less than 90 %. A decrease in these properties of composites at the content of the filler exceeding 60 % could be associated with the formation of a heterogeneous structure of filler. In the compositions with the highest performance characteristics, there is an optimized content of the filler and catalyst. Using a hardener and a curing catalyst in quantities of 3–3.5 and 1.5–2 %, respectively, makes it possible to shorten curing time by up to 2 hours. In general, the resulting epoxy composites are superior in their performance to known cold-curing analogs. The dependences of impact resistance, softening temperature, and cross-linking degree on the content of waste in the composite were derived, which make it possible to calculate the optimal formulation for composites depending on the required properties. Стаття присвячена проблемi утилiзацiї пилу металургiйної промисловостi як армуючого наповнювача епоксидних композитiв. Розроблена i дослiджена полiмерна композицiя "холодної зварки", що включає епоксидний дiановий олiгомер, амiнний затверджувач i наповнювач – дрiбнодисперснi вiдходи металiв. З метою пiдвищення теплостiйкостi i мiцнiстних характеристик в якостi затверджувача використовувався полiетиленполамiн. Для зниження температури i скорочення часу затвердiння в якостi прискорювача використовувався триацетат марганцю. Встановлена можливiсть утилiзацiї дрiбнодисперсних металовмiсних вiдходiв металургiйних виробництв в якостi наповнювача епоксидних композитiв холодного затвердiння. Виявлено, що оптимальний вмiст пилу ливарних виробництв в композитi знаходиться на рiвнi 45–60 %. При цьому вмiстi спостерiгається найвища ударна мiцнiсть на рiвнi 40–50 МПа i температура розм'якшення в iнтервалi 170–190 oС. Встановлено, що iз збiльшенням кiлькостi наповнювача вiд 40 % до 70 % ступiнь зшивання зростає вiд 88 % до 98 % вiдповiдно. Проте, при вмiстi наповнювача менше 45 % або бiльше 60 % знижується ударна мiцнiсть одержаних композитiв. Застосування затверджувача i прискорювача затвердiння в кiлькостях 3–3,5 i 1,5–2 % вiдповiдно дозволяє знизити час затвердiння до 2 годин. При вмiстi наповнювача в композитi менше 45 % причиною низьких значень ударної мiцностi i температури розм'якшення може бути низький ступiнь зшивання менше 90 %. Зниження вказаних властивостей композитiв при вмiстi наповнювача бiльше 60 % може бути пов'язано з утворенням неоднорiдної структури наповнювача. У композицiях з найвищими експлуатацiйними характеристиками спостерiгається оптимiзований вмiст наповнювача i прискорювача. В цiлому, одержанi епоксиднi композити за своїми експлуатацiйними характеристиками перевершують вiдомi аналоги холодного затвердiння. Встановленi залежностi ударної мiцностi, температури розм'якшення i ступеня зшивання вiд вмiсту вiдходiв в композитi, що дозволяють розраховувати оптимальний склад композитiв залежно вiд необхiдних властивостей.

Plasterboard is one of the most-commonly used construction materials because of its low cost and easy installation characteristics. Although the low strength and fragility make plasterboard functioned as non-load-bearing components. Plasterboard walls are always required to satisfy impact resistance against impact from accidental body strike, hard-body impact from wheelchair, etc. during its usage. This study investigates the impact resistance capacity of plasterboards being subjected to soft-body impact load . Laboratory sandbag impact tests are conducted to examine the responses of plasterboard and PP fibre strengthened plasterboard system at different velocities. Detailed numerical models of plasterboards are also generated to assist the analysis. Different damage and failure modes are observed on the plasterboards when subjected to impactor strike at different velocities. It is found that the coupled deformation of plasterboard and sandbag leads to different impact load time histories from sandbag soft impact, which results in the different failure modes. The PP fibre strengthened board exhibits better impact resistance than conventional plasterboard. Parametric study is then conducted to quantify the peak central deflections under different strength and thickness variances on plasterboard. An empirical formula is then derived based on the parametric results for preliminary assessment of the plasterboard impact resistance capacity.

This research examined the performance of functionally graded two-stage fibrous concrete (FTSFC) against modified repeated falling-mass impacts. This study led to the concept of creating improved multiphysics model of fibre composites with better impact resistance for potential protective constructions. FTSFC was developed based on the bio-inspiring strength of turtle shells. The excellent impact resistance of FTSFC was accomplished by including a larger quantity of steel and polypropylene fibres in the outer layers. At the same time, one- and two-layered concrete were cast and compared to evaluate the efficiency of three-layered FTSFC. To minimize the dispersed test results, a modified form of the 544 drop-mass impact test was recommended by the American Concrete Institute (ACI). The modification was a knife-edge notched specimen instead of a solid cylindrical specimen without a notch. This modification predefined a crack path and reduced the dispersion of results. Cracking and failure impact numbers, ductility index, and failure mode were the testing criteria. The suggested modification to the ACI impact test decreased the coefficient of variance, showing that the dispersion of test results was reduced significantly. This study led to the concept of creating improved, fibre composites with better impact resistance for potential protective constructions.

For diamond coating, natural fragile property easily leads to fracture, delamination and peeling, which seriously inhibits the applications in many industrial fields. In order to prolong the lifetime, improving the toughness under impact load is essential for diamond coating. In this work, a novel method was proposed by the conventional CVD diamond technique combining with the particles, with which the nanocrystalline diamond (NCD) coating with W particles (W-NCD) was fabricated to evaluate the impact behavior. The pure NCD coating was also produced for comparison. Repeating impact testing was performed to evaluate the impact resistance of the as-deposited NCD coatings. The results showed that the diamond coating can be fabricated on the substrate with W particles. The indentation scar revealed that the W-NCD coating had the stronger impact resistance than the NCD coating. Ratcheting effect was employed to discuss the impact properties of NCD coating for the first time. The coating integrity played a vital role in ratcheting displacement. Repeating impact can make the NCD and W-NCD coatings soft, and the W particles can accelerate the softening process. Hence, embedding particles can provide a potential and valid method to enhance the impact resistance of diamond coating that was very important for the fragile coating.

In this work, a new composite material with excellent dynamic impact resistance and outstanding quasi-static mechanical properties was synthesized. The composite material is composed of a polyurethane elastomer and a novel nano-polymer. The nano-polymer was composed of silane coupling agent-modified alumina microspheres and functionalized ionic liquids by double bond polymerization. The universal testing machine and split Hopkinson pressure bar were used to characterize the compression behavior, strength and energy absorption of the composite materials under static and dynamic conditions. Additionally, the comprehensive mechanical properties of polyurethane elastomer with different nano-polymer loadings (0.5–2.5 wt.%) were studied. The results show that whether it was static compression or dynamic impact, the polyurethane elastomer with 1% nano-polymer had the best performance. For the composite material with the best properties, its compressive yield strength under the static compression was about 61.13% higher than that of the pure polyurethane elastomer, and its energy absorption of dynamic impacts was also increased by about 15.53%. Moreover, the shape memory effect was very good (shape recovery is approximately 95%), and the microscopic damage degree was relatively small. This shows that the composite material with the best properties can withstand high compression loads and high-speed impacts. The developed composite material is a promising one for materials science and engineering, especially for protection against compression and impacts.

Due to the introduction of highly restrictive safety and pollution legislations in the railway industry, weight reduction has become an increasingly important topic over the last decade. Carbon fibre-reinforced polymers (CFRPs) constitute an excellent alternative to traditional materials, due to their highly specific in-plane mechanical properties. Their use in railway industry, however, is currently hindered by their weak out-of-plane properties. Bogies and underframes are often subjected to impact loadings caused by objects and debris surrounding the tracks (i.e. ice, ballast) that become airborne during the train transit and impact lower part of the carriage. While metal structures absorb impact energy via plastic deformation, barely visible impact damage can occur in CFRP, weakening the component, and often leading to catastrophic failures. This work proposes a method for the improvement of impact absorption performance of railway composite structures via the addition of a thermoplastic polyurethane (TPU) coating to CFRP laminates. The thermomechanical behaviour of the thermoplastic layer was investigated with dynamic mechanical analysis and differential scanning calorimetry analysis to optimize the manufacturing process, while damping tests were carried out to demonstrate its unaltered energy absorption ability in the final manufactured structure. TPU/CFRP plates (150 × 100 mm2 of in-plane size) were subjected to 2, 3 and 5 J impacts, and the results were compared with those of traditional CFRP laminates. Non-destructive test (NDT; i.e. C-scan, phased array) and compression-after-impact test were carried out on the impacted samples to assess the damaged area and residual in-plane mechanical properties. Results show that the TPU layer modifies the energy absorption mechanism, preventing the propagation of damage within the CFRP and resulting in undamaged samples even at the highest energy. To predict the TPU/CFRP impact behaviour and identify the best process parameters to optimize impact energy absorption, a finite element model was developed and validated using experimental data. The comparison showed good correlation, and a fine approximation of the different impact mechanisms was observed with a maximum error of 5% between experimental and simulated output values. The experimental and numerical results show that the TPU/CFRP laminates constitute a novel solution for the manufacturing of lighter and safer railway composite structures.

Impact resistance, water transport properties and sodium sulphate attack are important criteria to determine the performance of concrete incorporating mixed types of recycled plastic waste. Nine mixes were designed with different combinations of the three plastic types, Polyethylene terephthalate (PET), High density polyethylene (HDPE) and Polypropylene (PP). The plastic partially substituted the coarse aggregate (by volume) at various replacement ratios, 10%, 15%, 20% and 30%. The impact resistance and water transport properties were evaluated for nine mixes while sodium sulphate attack test was performed for three mixes. The results showed that the addition of mixed recycled plastic in concrete improved the impact resistance. The highest impact resistance improvement was achieved by R8 (PET + HDPE + PP) at 30% replacement which was 4.5 times better than the control mix. Water absorption results indicated a slight increase in all plastic mixes while contradictory results were observed for sorptivity test. Analysis of sodium sulphate attack results showed that incorporating 30% mixed plastic reduced the sodium sulphate resistance slightly due to the collective effect of plastic entrapping of sulphate ions after 80 cycles. This study has shown some positive results relating to the impact performance of Mixed Recycled Plastic Concrete (MRPC) which enhances its use in a sustainable way.