High Impact Tests Research Articles

Design and application of FBG shock sensor for high-G shock tester and a wider frequency range

This study explores the potential of employing arrays of FBG shock sensors to measure strain in high-G impact test systems. Through a meticulously designed experiment, we installed three FBG arrays into grooves on the bottom surface of high-impact test equipment, ensuring a seamless profile. The unique design of the double elastic mass induced acceleration in the grating fiber while simultaneously subjecting it to stretching or compression in the opposite direction. This innovative approach allows us to evaluate the feasibility and effectiveness of utilizing FBG vibration sensors for precise strain measurement in high-G impact scenarios. The natural frequency and sensitivity of the sensor were theoretically investigated and optimized using MATLAB software. Furthermore, ANSYS was used to analyze the models and conduct simulations. The simulated FBG sensor had a natural frequency of 5000 Hz and demonstrated a flat frequency range of 100–3500 Hz. The linearity of the average sensitivity is 2.77 pm/G. A high-impact FBG shock sensor can measure high-impact forces or vibrations accurately, including aerospace to monitor aircraft health, automotive to improve vehicle safety, defense to detect gunfire, and sports to monitor the impact of collisions and improve athlete safety.

Assessing Feed-Forward Backpropagation Artificial Neural Networks for Strain-Rate-Sensitive Mechanical Modeling.

The manufacturing processes and design of metal and alloy products can be performed over a wide range of strain rates and temperatures. To design and optimize these processes using computational mechanics tools, the selection and calibration of the constitutive models is critical. In the case of hazardous and explosive impact loads, it is not always possible to test material properties. For this purpose, this paper assesses the efficiency and the accuracy of different architectures of ANNs for the identification of the Johnson-Cook material model parameters. The implemented computational tool of an ANN-based parameter identification strategy provides adequate results in a range of strain rates required for general manufacturing and product design applications. Four ANN architectures are studied to find the most suitable configuration for a reduced amount of experimental data, particularly for cases where high-impact testing is constrained. The different ANN structures are evaluated based on the model's predictive capability, revealing that the perceptron-based network of 66 inputs and one hidden layer of 30 neurons provides the highest prediction accuracy of the effective flow stress-strain behavior of Ti64 alloy and three virtual materials.

Analisis Sifat Mekanik Komposit Serat Sabut Kelapa dengan Perlakuan Alkalisasi Etanol dan Filler Arang Tempurung Kelapa

Coconut trees are plants that are easily found in tropical areas such as Indonesia; therefore, natural products are abundant, but the use of waste from coconuts has not been processed into technological products. The aim of this study was to determine the differences in the variations in the volume fraction of fibers during tensile and impact strength testing. The variations in the volume fraction used were 5%, 10%, and 15% fiber, and the chemical treatment of the fiber was alkalized using 20% ethanol for 3 h of soaking. Composite manufacturing uses a hand layup method with random fiber orientation. The results of the research on variations in volume fraction of 5%, 10% and 15% obtained test values, in tensile testing such as maximum load obtained 32,844 kgf, 106.44 kgf and 105.59 kgf, maximum stress 6.0510 N/mm2, 16,893 N/ mm2 and 17.249 N/mm2, elongation breaking strain 0.8150, 0.3275 and 0.2617, breaking strain 1.4818 %, 0.5955 % and 0.4758 %, for the tensile test value the impact energy value was found to be 1.6 kgf, 2.3 kgf and 3.3 kgf and impact prices of 1.84 kJ/m2 , 2.45 kJ/m2 and 3.45 kJ/m2 . The high tensile and impact test results were due to mixing coconut fiber which had gone through ethanol alkalizing treatment with coconut charcoal powder to obtain high impact and tensile values.

Effect of Moisture on the Mechanical Properties of Wood-Plastic Composites Hybridized with Metal Grid Layers.

Wood-plastic composites (WPCs) are some of the most common modern composite materials for interior and exterior design that combine natural waste wood properties and the molding possibility of a thermoplastic polymer binder. The addition of reinforcing elements, binding agents, pigments, and coatings, as well as changes to the microstructure and composition, can all affect the quality of WPCs for particular purposes. To improve the properties, hybrid composite panels of WPCs with 30 wt. % and 40 wt. % of wood content and reinforced with one or three metal grid layers were prepared sequentially by extrusion and hot pressure molding. The results show an average 20% higher moisture absorption for composites with higher wood content. A high impact test (HIT) revealed that the absorbed energy of deformation increased with the number of metal grid layers, regardless of the wood content, around two times for all samples before water immersion and around ten times after water absorption. Also, absorbed energy increases with raised wood content, which is most pronounced in three-metal-grid samples, from 21 J to 26 J (before swelling) and from 15 J to 24 J (after swelling). Flexural tests follow the trends observed by HIT, indicating around 65% higher strength for samples with three metal grid layers vs. samples without a metal grid before water immersion and around 80% higher strength for samples with three metal grid layers vs. samples without a grid after water absorption. The synthesis route, double reinforcing (wood and metal), applied methods of characterization, and optimization according to the obtained results provide a WPC with improved mechanical properties ready for an outdoor purpose.

Effects of Heat Input on Weld Microstructure and Properties in Keyhole TIG Welding of Invar 36 Alloy.

The Invar alloy is widely used for aircraft wing mould manufacturing. In this work, keyhole-tungsten inert gas (K-TIG) butt welding was used to join 10 mm thick Invar 36 alloy plates. The effect of heat input on the microstructure, morphology and mechanical properties was studied by using scanning electron microscopy, high energy synchrotron X-ray diffraction, microhardness mapping, tensile and impact testing. It was shown that regardless of the selected heat input, the material was solely composed of austenite, although the grain size changed significantly. The change in heat input also led to texture changes in the fusion zone, as qualitatively determined with synchrotron radiation. With increases in heat input, the impact properties of the welded joints decreased. The coefficient of thermal expansion of the joints was measured, which demonstrated that the current process is suitable for aerospace applications.

Research on Mechanical Properties of Domestic T700S Carbon Fibers

Two types of domestic T700S carbon fibers (CF1 and CF2) were investigated in three batches to find out their mechanical properties, including tensile properties of multifilament, tensile and bending properties of composites. The results showed that the mechanical properties of domestic T700S CF are comparable to those of Toray T700S CF with a small discrete coefficient obtained from experiments for the three batches of CF, and that the unidirectional CF2 composite laminates has the biggest tensile strength discrete coefficient, 3.84%. The difference of properties between the two types of fiber composites was analyzed using the optical contact angle measuring device. It was found that CF2 and resin have better wettability. The two types of carbon fibers were examined by the Ø150 mm standard pressure vessel. Temperature (high temperature, low temperature, and temperature impact) tests and aging tests revealed that: high temperature, low temperature, and temperature impact have little effect on the characteristic index of the pressure vessel; after 800h aging, the characteristic index of the pressure vessel decreased by 15.2%.

Experimental Study on the Influence of Moisture and Clay Content on Stress Wave Attenuation Characteristics of Filled Joints

Artificial filled joints made of sand–clay mixtures with different clay weight fractions and saturations have different wave attenuation capacities. In this paper, the high amplitude impact test of sand–clay mixtures was carried out by using split Hopkinson pressure bar (SHPB) equipment. The results showed that with the increase of clay weight fraction, the particle crushing decreased continuously, while the wave attenuation coefficient decreased first and then increased. When the weight fraction of clay was 50%, the wave attenuation coefficient reached the minimum among the tested working conditions, and the ratio of transmitted energy to incident energy reached the maximum. With the increase of saturation, the particle crushing decreased first and then increased, while the wave attenuation coefficient increased first and then decreased. When the saturation was 25%, the wave attenuation coefficient reached the maximum, and the proportion of transmitted energy to incident energy reached the minimum. Because of the lubrication of water reduced the friction between particle, the specimen more prone to deformation and particle crushing reduced. As the saturation increased, this effect gradually decreased. In the case of the wave absorbing layer of protective works, special attention should be paid to the adverse effects caused by groundwater.

High-impact testing that inspires action

This paper outlines a simple framework for data storytelling that communicates experimentation programme test results focused on stakeholder actionability rather than test performance. This framework can be applied both as a narrative and a visualisation guide within a company’s existing analytics tool. Its benefits for a business mirror the true returns from investing in an experimentation programme — not the percentage lift of a single test treatment, but the application of test results to how the business might de-risk decision-making, optimise marketing efforts, or prioritise its product roadmap. This approach supports experimentation maturity by (1) giving stakeholders access to test learnings, (2) sharing how stakeholders can use learnings, (3) building institutional intuition of how to talk to different customer audiences or develop new products/features, (4) enabling insights to guide next right actions, and (5) helping others understand the potential application of experimentation and the benefits of testing.

An Improved Synthesis of Bromotetrazole

AbstractA new efficient synthesis of 5‐bromotetrazole is presented. The free acid bromotetrazole was synthesized in a straightforward reaction analogous to the production of nitrotetrazole. Its sodium salt was readily produced via acid/base salt metathesis. Both products were characterized chemically and as energetic materials by 1H and 13C NMR, IR, High Resolution Mass Spectrometry, x‐ray crystallography, TGA, impact and friction tests.

Assessing the effectiveness of UHPFRC, FRHSC and ECC against high velocity projectile impact

High velocity projectile impact (HVPI) test was carried out on three classes of cement composites to assess their performance. The tests were conducted on thick block specimens using non-deformable ogive-nosed projectiles with a mass of 250 g and a diameter of 28 mm at approximately 400 m/s. The severity of damage was quantified by the depth of penetration (DOP), equivalent crater diameter (ECD), crater volume (CV), and crater profile (CP). The ability of cement composites to resist the HVPI in terms of DOP seems to be influenced by aggregates because cracks are forced through aggregate at the high strain rate under HVPI. The energy absorption capacity under direct tension is found to be more relevant than flexural toughness in controlling CV and CP. Transient temperature under HVPI is likely elevated to about 250 °C in the ultra-high performance fiber reinforced concrete (UHPFRC), which may lead to higher internal pressure built-up (thus damage) than the engineered cementitious composites (ECC).

Establishing a Cold Spray Particle Deposition Window on Polymer Substrate

A set of processing conditions for cold spray deposition of an embedded particle layer on a polymer substrate has been established using a dynamic impact model and verified experimentally. This research utilizes a three-network polymer model based on high strain-rate impact tests to capture the nonlinear and time-dependent response of polymer deformation during the cold spray impact with both rigid and deformable particles. The particle's material properties, particle velocity, and particle size were systematically studied to obtain the polymer deformation's various responses from finite element analysis. Particle impact velocity was experimentally measured with a double disk rotary system. The numerical results were mapped into diagrams and validated with the experimental results of cold spraying Cu and Al2O3 powders. This research contributes to quantifying the deposition window, which embeds but still exposes metallic/ceramic powders on a polymer substrate.

Simulation of life-like distal humerus and olecranon fractures in fresh frozen human cadaveric specimens

Abstract Background Economic burden and personnel shortages lead to a reduction in the time spent on surgical training of young resident physicians. This underlines the importance of courses for learning and optimizing surgical skills. Particularly for orthopaedic trauma surgery, training on fractured cadaveric specimens has proven highly useful. The present study investigates a method to induce realistic fracture patterns in fresh frozen elbow specimens, leaving the skin and soft tissue envelope intact. Methods For fracture simulation, 10 human cadaveric specimens with intact soft tissue envelopes were placed in 90° flexion in a custom-made high-impact test bench and compressed by an impactor. The fractures were subsequently classified using conventional x‑rays. Results Of the 10 specimens, 6 could be classified as distal humerus fractures and 4 as olecranon fractures. The fractures of the distal humerus were mainly type C according to Arbeitsgemeinschaft Osteosynthesefragen (AO) criteria, the olecranon fractures were mainly type IIB according to the Mayo classification. Subsequently, all 10 specimens would have been appropriate for use in musculoskeletal trauma courses. Conclusion With the given setup it was possible to induce realistic fracture patterns in fresh frozen cadaveric specimens. The advantage of the presented technique lies in the preservation of soft tissue. With their intact soft tissue envelopes, these pre-fractured preparations could be used in courses to precisely train resident physicians directly on human cadaver preparations. Further research should focus on finding reliable predictors to improve the precision of fracture induction in specimens.

Experimental study on CFRP-concrete dynamic debonding behaviour

Carbon fibre reinforced polymer (CFRP) is widely used in strengthening structures against dynamic loading. However, debonding is one of the primary failure modes in CFRP strengthened reinforced concrete (RC) structures. This phenomenon is controlled by the interfacial shear bond-slip behaviour between the two materials, viz. CFRP and concrete. Although the quasi-static bond-slip response has already been extensively investigated, studies on their dynamic behaviour are rather limited, especially those under high loading rate regime. Limited knowledge of the interface behaviour will affect high-fidelity simulations of FRP strengthened RC structures under dynamic loading regime. To shed light on the FRP bond-slip behaviour under high loading rates (above 800 mm/s), the authors proposed a novel experimental method for high loading-rate impact tests using a modified Split Hopkinson Pressure Bar (SHPB) set-up. Based on this set-up, slip rate could be derived through single-lap shear tests under impact loading regime. Dynamic enhancing effect on ultimate load, shear bond stress and fracture energy could be quantified for a wide range of loading rates varying from 0.02.mm/s to 2150 mm/s. It was found that the bond-slip properties showed remarkable dynamic enhancing effect under high loading rate (above 800 mm/s). However, at the loading rate around 2000 mm/s, dynamic effect could be limited by CFRP load capacity in which the CFRP sheet might directly fractured rather than debonded from the concrete surface. The effect of parameters on the bond behaviour was better understood from a detailed experimental parametric study. Constitutive equations were proposed to model the dynamic bond-slip behaviour of the CFRP-concrete interface.

Design of Travelling-Wave Rotating Ultrasonic Motor under High Overload Environments: Impact Dynamics Simulation and Experimental Validation

Nowadays, piezoelectric actuators are widely used, but are rarely applied in high overload environments due to th difficulty implementing them. Traveling wave rotary ultrasonic motors (TRUMs) have the characteristics of variable structure and are insensitive to overload, endowing them with the potential ability of high overload resistance. In this study, four TRUMs with different rotor structures are designed to work under the high-impact acceleration of 10,000 g through modifying the rotors with a designed slotted disc spring. The dynamics model is established, the impact process is simulated, and the results are analyzed successively. The high-impact test, deformation measurement and performance test of the motors are carried out to verify the modification. The results show that performance of the TRUMs with a disc spring declines much less than those without a disc spring after the high-impact test. The TRUM-4 with the modified rotor and disc spring has the best performance, the speed of which decreased only 1.6% at the torque of 0.15 N m, and it is considered to be capable of withstanding the high acceleration of 10,000 g. This work is significance for guiding the ultrasonic motors’ optimization to expand their application in high-overload environments.

Boxception: Impact Resistance Structure Using 3D Printing

The emergence of 3D printing has enabled scientists to innovate complex geometrical designs in materials which are unattainable using conventional synthesis methods. The topological material design is becoming a common occurrence aided by 3D printing. This work reports on a high load‐bearing structure by leveraging geometry using simple elastic polymers. We use the “Boxception” concept commonly used in packaging to design a structure where the open cubes are joined at their edges. The modeled structure is then printed with help of a 3D printer using polyvinyl alcohol (PVA) filament. Such design allows the outer boxes to act as shielding members to the inner‐most box. Both experimental and finite element methods (FEM) are used to understand the deformation response of the structure. Experimental investigations through compression and high impact tests along with finite element simulations conclude the inherent ability of the boxception structure to prevent failure of the inner box due to the dispersed force distribution offered by the unique structure. It is further shown that the improvement in impact and load‐bearing capacity is greatly influenced by the geometry of the structure. The unique structural design “Boxception” proposed can form primary load bearing component of sandwiched structures ensuring superior energy mitigation even under impact loads.

High temperature wear mechanisms in thermally oxidized titanium alloys for engine valve applications

Titanium alloys are promising lightweight materials to replace the conventional use of stainless steels in engine valve applications, but their high temperature wear resistance should be improved. In this study, a thermal oxidation (TO) treatment (at 600 °C for 60 h) was utilized on Ti-6Al-4V to generate a surface rutile, TiO2, layer with a hardened oxygen diffusion zone underneath. Sliding wear tests were performed on untreated Ti-6Al-4V and TO-Ti-6Al-4V disks against cast iron pins at 350 °C and 550 °C, typical temperatures at which intake and exhaust engine valves operate. In addition, high temperature impact tests were conducted to study the deformation and fracture mechanisms of surface layers produced on TO-Ti-6Al-4V. The results showed that compared with untreated Ti-6Al-4V, TO-Ti-6Al-4V exhibited lower sliding wear losses at both test temperatures. The lowest wear loss was observed at 550 °C due to the preservation of both TiO2 layer and oxygen diffusion zone, and the propensity of impact crack growth was also reduced. The oxygen diffusion zone reduced the extent of subsurface plastic deformation and contributed to improved wear resistance.

Investigation on the thermal butt fusion performance of the buried high density polyethylene piping in nuclear power plant

Abstract This paper presents the effect of fusion procedure on the fusion performance of the thermal butt fusion in the safety class III buried HDPE piping per various tests performed, including high speed tensile impact, free bend, blunt notched tensile, notched creep, and PENT tests. The suitability of fusion joints and qualification procedures was evaluated by comparing test results from the base material and butt-fusion joints. From the notched tensile test result, it was found that the fused joints have much lower toughness than the base material. It was also identified that the notched tensile test is more desirable than the high speed tensile impact and free bend tests presented in the ASME Code Case N-755-3 as a fusion qualification test method. In addition, with regard to the single low-pressure fusion joint performances, the procedure given by the ISO 21307 was determined to be better that the one specified in the Code Case N-755-3.

Simulation and Experimental Research of Continuous High Impact Test Equipment

In order to realize the simulation test of key components under continuous high impact environment, a continuous high impact test equipment based on direct impact loading of multiple impact heads is designed. In view of the collision contact problem between the impact head of semi-cylindrical structure and the tested object, a mathematical model of collision contact force is established based on Hertz line contact theory and hysteretic damping model, the change of the contact force and the energy loss are described in the form of nonlinear elastic force and equivalent damping, provide theoretical support for impact parameter analysis of the test equipment. On the basis of theoretical analysis, the overload acceleration of continuous high impact test equipment is verified combined with dynamic simulation and experiment, demonstrate the rationality and feasibility of the test equipment design.

Polypropylene nano-composites at high strain rate impacts: Characterization, failure modes, and modeling

As a major challenge, development of light-weight fibre reinforced polymer (FRP) composite body armour, characterization of candidate matrix polymers at high strain rate impact is the focus in this research. Polypropylene (PP) and the nano-composites with 1-5% by weight of NC (nanoclay) platelets are the candidates considered. In the characterization phase, high strain rate impact and quasi-static loading tests were performed to figure out the limiting (failure) responses. Comparison between the material systems is, subsequently, made to nominate one matrix configuration. Enhancements of mechanical properties with increase in weight percentage of the nanoparticles are observed at both quasi-static and dynamic loadings. Observations of dispersed imposed failure modes, development of novel model for failure modulus and evaluation of peak strength values are also attempted. Keywords : Nano-composite, Impact behaviour, Analytical modelling, Polypropylene, Failure mode.

High temperature impact testing of a thin hard coating using a novel high-frequency in situ micromechanical device

High-impact applications such as forging, punching or fine blanking often utilise hard-coating systems to improve wear and lifetime performance. For rational design of such systems, evaluation after repeated impacts at the application temperature is critical. However, such investigations are time-consuming and costly to perform in-line on an industrial scale. Small-scale impact testing allows for rapid and inexpensive investigation of attractive thin coating designs, which can be performed over a range of controlled temperatures. Here, a novel in situ nanoindentation device was developed, able to perform precise displacement cycles to 1kHz at temperatures up to 500°C within a scanning electron microscope. The system is based on a piezoelectric driving tip containing four discrete piezo devices, allowing for the collection of load-displacement data for each individual cycle. Operation of the device at 500Hz was demonstrated on arc-PVD chromium nitride coated nitrided steel with a diamond flat-punch counter-body, and the effects of temperature and impact number on fatigue deformation studied using electron microscopy techniques. It was found that as the impact number increased as did the residual plastic damage from the impact force. Additionally, the deformation of the tooling was highly dependent on the temperature, which became more strongly apparent with an increased number of impacts. Such testing will be useful for evaluating the lifetime and fatigue properties of potential new thin films and coatings for high-impact operations, where understanding the influence of temperature is crucial.