Ultimate Tensile Strength Of Material Research Articles

Stability analysis of civil air defense tunnel under blasting vibration

Based on a large section drilling and blasting excavation project, the dynamic response characteristics of civil air defense tunnels are analyzed by combining field monitoring and numerical simulation. The dynamic response features include particle vibration velocity, main frequency, displacement, and stress, and the stability criterion of the tunnel is analyzed. A safety criterion model based on the ultimate tensile strength of materials is established. The results show that the frequency of the X, Y, and Z directions is mainly distributed in 90-140 Hz. The effective stress increases first and then decreases along the axis of the roadway. The stress near the explosion source is large and the relative reduction is also large. By fitting the relationship between blasting vibration velocity and maximum principal stress, the safe vibration velocity criterion based on tensile strength is obtained, and the safe threshold of vibration velocity is 19.62 cm/s. It can be assumed that blasting does not affect the structure.

Fatigue Simulations for Automotive Components undergoing Vibration Loadings: effect of nonlinear behavior

Modern automotive customers are demanding for faster and faster product development, from initial response for quotation (RFQ) to serial production. Finite Element Analysis (FEA) is a powerful tool applied to design validation (DV). In Valeo, FEA and Reliability teams have been working together to establish a robust methodology for the simulation of vibration fatigue at the design validation phase.This paper goes in the framework of using modern simulation tools to routinely validate the goodness of a design.Previous investigations had shown that “simple” DV simulation based on the material's ultimate tensile strength (UTS) tend to be conservative and basically targeting an infinite fatigue life endurance.The present study aims at simulating the design validation of relatively complex systems (multi-materials components, prototype parts, representative system integration) in the high cyclic fatigue domain: the goal is to rely on FEA as early as possible even before official nomination (e.g. RFQ phase).This paper will present an example of a car engine cooling module (ECM) undergoing vibration loadings.The simulated fatigue will be obtained by different calculation methods, such as modal linear and non-linear approaches and time domain methods. A case study will illustrate a practical application of the presented methods. The results of the different methodologies, expressed as predicted time to failure, will be compared and analyzed.The objective of the study is to compare the results obtained from the different approaches when applied to durability design validation of an industrial cooling system undergoing vibration fatigue loadings.

High-speed friction stir butt welding of 25.4 mm thick 7175-T79 aluminum alloy

This study presents the first experimental demonstration of high-speed friction stir butt welding of 25.4 mm thick AA7175-T79 aluminum alloy. The utilization of friction stir welding (FSW) tool pin threads that terminate away from the shoulder region reduced stress concentration during tool traversing. This tool design enabled a welding speed above 500 mm/min and a penetration depth greater than 10 mm without pin fracture near the shoulder. Two types of welds were performed: one-sided with full penetration and double-sided with partial penetration of the plate thickness. The junction of the double-sided friction stir welding (FSW) exhibited significant grain refinement (grain size 1.3 ± 0.8 μm) compared to other regions. Cross-weld tensile testing revealed high local strains at the double-sided FSW junction, which improved the yield strength by 20–24% compared to slower one-sided FSW. The joint efficiency of the as-welded, high-speed double-sided FSW was approximately 76% of the base material's ultimate tensile strength.

Investigation on regression model for the force of small punch test using machine learning

The analytical solution for the force-deflection curve of the small punch test (SPT) is still a challenge. Machine learning is employed in the present study to establish a model for estimating SPT forces by using the strength of a material. The yield strength and ultimate tensile strength of materials and corresponding SPT force-deflection curves generated by finite element simulations are the training and testing data for machine learning. Pearson correlation analysis was performed first to measure the statistical association between the SPT force at a given deflection and the strength of materials. It was shown that a binary linear regression model was capable of correlating SPT forces to the yield strength and ultimate tensile strength of a material. The model parameters were determined after training, and then this model was tested by testing data. The accuracy of the regression model was verified by hypothetical materials, X70 steel and Incoloy 800H alloy. This study gives a new insight into the relationship between force responses of SPT and material properties, and can promote the development of novel approaches for determining material tensile properties using SPT.

A compendious review on fatigue properties of the bio‐nanocomposites

AbstractIn this present work, a review of fatigue strength on bio‐nano composites was presented. Generally, the biocomposites possessed higher fatigue strength than the conventional materials. Because the propagation in biocomposites can be arrested due to their internal structure, whereas the damages occur in the matrix and/or at the fiber/matrix interface region. In the case of conventional materials, the cracks would rapidly grow until a catastrophic failure occurs. Thus, the S–N curves of composites show a flatter curve when compared to the conventional materials. In terms of fatigue properties, conventional fiber‐reinforced composites (e.g., glass and carbon‐reinforced composites) were more extensively studied than bio‐based reinforced composites. Examining the fatigue properties of materials is significant for all engineering‐based applications. Because the fatigue failures can occur below the ultimate tensile strength of materials. However, the fatigue performance of the composites can be enhanced by improving the fiber‐matrix interfacial bonding resulting from surface treatment of fibers and incorporating nanofillers within the matrix, and so forth. Since the nanocomposites have a larger surface area and aspect ratio, they are preferred to use in many applications: aerospace, automotive, biotechnology, construction, and building, electronics, marine, and packing industries. Thus, this chapter starts with the unique advantages of bio‐nano composites. Then, the fatigue properties of bio‐nano composites, the significance of the S–N diagram, and the pattern of fatigue testing were discussed. In order to understand the fatigue behavior, several factors such as structure, fillers, fabrication techniques, and so forth were included. Challenges of fatigue strength of biocomposites were also summarized.

Fatigue Performance of Natural and Synthetic Rattan Strips Subjected to Cyclic Tensile Loading

Tensile fatigue performances of selected natural rattan strips (NRSs) and synthetic rattan strips (SRSs) were evaluated by subjecting them to zero-to-maximum constant amplitude cyclic tensile loading. Experimental results indicated that a fatigue life of 25,000 cycles began at the stress level of 50% of rattan material ultimate tensile strength (UTS) value for NRSs evaluated. Rattan core strips’ fatigue life of 100,000 cycles started at the stress level of 30% of its UTS value. Rattan bast strips could start a fatigue life of 100,000 cycles at a stress level below 30% of material UTS value. SRSs didn’t reach the fatigue life of 25,000 cycles until the applied stress level reduced to 40% of material UTS value and reached the fatigue life of 100,000 cycles at the stress level of 40% of material UTS value. It was found that NRSs’ S-N curves (applied nominal stress versus log number of cycles to failure) could be approximated by S=σou(1−H×log10⋅Nf). The constant H values in the equation were 0.10 and 0.08 for bast and core materials, respectively.

Fatigue and Damage Assessment of CFRP Material Using Digital Image Correlation

Fatigue testing of a Carbon Fiber Reinforced Polymer (CFRP) in tension-tension loading has been conducted. In-situ surface strain measurements were performed to examine the gradual elongation of the specimen as this relates to stiffness loss and fatigue damage. A methodology capturing the specimen at peak load has been developed, including an automated trigger mechanism that activates the camera at the desired cycle count. The material tested was a Unidirectional (UD) Non-Crimp Fabric (NCF) with carbon fibers and an epoxy matrix. The fatigue test results revealed a wide scatter in the mid-range of the high cycle fatigue region. By studying the strain in the early fatigue loading cycles and the stiffness loss over time, benchmark of the fatigue performance between different material samples could be carried out, explaining the scatter in the fatigue testing. It could be observed that the fatigue limit of the UD CFRP material in the fiber direction is in the magnitude of 80 % of the material's Ultimate Tensile Strength (UTS).

Linear Dimensional Change and Ultimate Tensile Strength of Polyamide Materials for Denture Bases.

The aim of the current study was to evaluate the dimensional changes and ultimate tensile strength in three polyamide materials for denture bases fabrication through injection molding, subjected to artificial aging and different storage conditions. A total of 333 test specimens fabricated from Biosens (BS; Perflex, Netanya, Israel), Bre.flex 2nd edition (BF; Bredent, Senden, Germany) and ThermoSens (TS; Vertex Dental B.V., Soesterberg, The Netherlands)—n = 111 per material—were equally divided into three groups (n = 37) based on different treatments and storage conditions. Test samples allocated to the “Control group” were not artificially aged and stored in water for 24 h. Both “Treatment 1 group” and “Treatment 2 group” were subjected to thermocycling, the former dehydrated and the latter stored in water between cycle-sets. Linear changes and ultimate tensile strength were measured and analyzed for storage condition and material influence on the outcome variables. A Welch ANOVA test with Games–Howell post-hoc analysis was used to compare the influence of treatments across different materials. Significant differences were found for all three included materials with p values ranging from <0.05 to <0.001 for linear dimensional changes. The magnitude of alterations varied and was large for BS (Perflex, Israel) (ω2 = 0.62) and BF (Bredent, Germany) (ω2 = 0.47) and small but significant for TS (Vertex Dental B.V., The Netherlands) (ω2 = 0.05). However, results seem to fall into clinically acceptable range. Significant differences were also observed for the ultimate tensile strength test with the same range of p-values. All three materials showed different initial ultimate tensile strengths and varying reaction to artificial aging and storage with the lowest alterations observed for BF (Bredent, Germany) (ω2 = 0.05). Within the limitation of this study, it can be concluded that all three materials show different dimensional and mechanical properties when subjected to artificial aging and different storage. Although linear dimensions show significant changes, they seem to be clinically irrelevant, whereas the change in ultimate tensile strength after only 6-month equivalent clinical use was substantial for BS (Perflex, Israel) and TS (Vertex Dental B.V., The Netherlands).

Structural analysis of pulsed magnets considering interface characteristics.

The aim of traditional designs of pulsed magnets is to keep the von-Mises stress on the midplane less than the ultimate tensile strength of materials. However, recently failed high-field experiments showed that some short circuits occurred at the magnet end, which is most possibly caused by the axial displacement of wires. This indicates that the former design is inadequate and accurate axial mechanical analysis of magnets is necessary. In this paper, a finite element model of pulsed magnets considering interface characteristics is proposed. Both the contact status and interfacial friction between the conductor layers and reinforcements can be accounted for Simulations are conducted with a failed 95 T dual-coil prototype, which was originally designed with the self-developed Pulsed Magnet Design Software (PMDS) software. The simulation results show that all the originally expected separations calculated by the PMDS software disappear due to the compression. This makes the calculated maximal von-Mises stress of the inner four reinforcement layers about 600 MPa less than the former designs. The influence of the interfacial friction is also presented. Besides, the simulations show that the maximum axial displacement at the magnet end is up to 8 mm at the designed peak field, which is deadly to the insulations. Hence, we suggest that the axial displacement at the magnet end should also be one design objective of pulsed magnets. At last, the factors affecting the axial displacement are analyzed.

Biomechanical Response under Stress-Controlled Tension-Tension Fatigue of a Novel Carbon Fiber/Epoxy Intramedullary Nail for Femur Fractures

Metallic intramedullary nails are the “gold standard” implant for repairing femur shaft fractures. However, their rigidity may eliminate axial micromotion at the fracture (causing delayed healing) and they may carry too much load relative to the femur (causing “stress shielding”). Consequently, some researchers have proposed fiber-reinforced composite nails, but only one evaluated cyclic fatigue performance. Therefore, this study assessed the cyclic fatigue response of a carbon fiber/epoxy nail with a novel ply stacking sequence of [02/-45/452/-45/0/-45/452/-452/452/-45/902] previously developed by the present authors. Nails were cyclically loaded in tension-tension at 5 Hz with a stress ratio of R=0.1 from 30% - 85% of the material's ultimate tensile strength (UTS). Thermographic stress analysis, rather than conventional fatigue testing, was used to obtain high cycle fatigue strength (HCFS), below which the nail can be cyclically loaded indefinitely without damage. Also, the mechanical test machine's built-in load cell and an extensometer were used to create stress-strain curves, from which the change in static EO and dynamic E* moduli were obtained. Results showed that HCFS was 70.3% of UTS (or about 283 MPa), while EO and E* remained at 42 GPa without any dRegradation during testing. The current nail shows potential for clinical use.

Potential of distributed recycling from hybrid manufacturing of 3-D printing and injection molding of stamp sand and acrylonitrile styrene acrylate waste composite

In the Upper Peninsula of Michigan, over 500 million tons of copper rich rock were removed from mines and treated in chemical baths to extract copper. Toxic substances have been seeping into the watersheds from the resultant waste stamp sands. Recent work on developing a circular economy using recycled plastic for distributed manufacturing technologies has proven promising, and this study investigates the potential to use this approach to form stamp sand and acrylonitrile styrene acrylate (ASA) composites. Specifically, this study found the maximum amount of stamp sand that was able to be added to waste ASA by mass with a single auger recyclebot system for compounding was below 40%. The mechanical properties of the composite were evaluated up to 40%, and the addition of stamp sand reduced the material's ultimate tensile strength by about half compared to the strength of raw recycled ASA, regardless of the percent stamp sand in the composite. However, this strength reduction plateaus and the tensile strength of the ASA and stamp sand composites can be compared favorably with acrylonitrile butadiene styrene (ABS) at any level. This makes waste ASA- stamp sand composites potential replacements for outdoor applications of ABS as well as some current ASA applications. These results are promising and call for future work to evaluate the technical, economic and environmental potential for waste ASA - stamp sand composites.

Fracture loads for blunt notches under mode I loading

In the present study, fracture load evaluation technique for blunt notches under mode I loading is investigated using the mean stress based line criterion. Considering the effect of notch root radius ρ, a new fracture evaluation method, applicable not only for the V-shaped notches but also for other notches such as shallow notches, is developed, For a large notch root radius ρ (i.e. ρ>ρ|Cri-1), the notch fracture can be evaluated by a simple rule that the fracture occurs when the maximum stress σmax reaches the material ultimate tensile strength σC. If ρ is large adequately such that ρ|Cri-1>ρ>ρ|Cri-2, the notch fracture is evaluated as the fracture problem of a circle hole in an infinite plate. Here, ρ|Cri-1 and ρ|Cri-2 are the critical values for ρ to satisfy the σmax-alone condition and the ρ-alone condition, respectively. Moreover, as long as the V-notch condition is fulfilled by the notch geometry, the notch fracture under mode I loading can be treated as the fracture problem of V-shaped notches and evaluated by the generalized notch stress intensity factorKIV,R or the maximum stress at the notch root σmax. Whether the σmax-alone condition, the ρ-alone condition or the V-notch condition is fulfilled is mainly determined by the ratio of the characteristic length d0m to the geometric size of notched specimen.

Reference strength values to design against static and fatigue loading polylactide additively manufactured with in‐fill level equal to 100%

The aim of this paper is to provide a quantitative examination of the state‐of‐the‐art knowledge of the static and fatigue behaviour of additively manufactured (AM) polylactide (PLA). To this end, existing literature was reviewed, and a number of data sets were extracted and re‐analysed in terms of static strength and standard S‐N curves. As long as objects are 3D‐printed flat on the build plate, printing direction appears to have little effect on the mechanical behaviour of AM PLA, therefore stress/strain analysis can be performed effectively by simply treating this polymer as a linear‐elastic, homogenous, and isotropic material. If static strength cannot be determined experimentally, a conservative reference value of 22 MPa is suggested as being used in situations of practical interest. As far as fatigue is concerned, findings from post‐processing reveal that non‐zero mean stresses can be modelled by simply using the maximum stress in the cycle. According to the statistical re‐analysis discussed in the paper, a reference fatigue curve for the design of AM PLA subjected to uniaxial cyclic loading (for a probability of survival larger than 90%) can be defined by taking the negative inverse slope equal to 5.5 and the endurance limit (at 2·106 cycles to failure) equal to 10% of the material ultimate tensile strength.

Simulation-based Prediction of Structural Design Failure in Fishing Deck Machinery a Hydraulic Type with Finite Element Method

The fishing deck machinery is the tools used to collect fish in fishing activities. Fishing deck machinery is intended to improve the effectiveness of fishing operations. The mission of the Ministry of Marine Affairs and Fishery Year 2015-2019 in the Regulation of the Minister of Marine and Fisheries No. 45/PERMEN-KP/2015 which is a priority is to provide assistance for fishing facilities for fishermen; it is necessary to develop and optimize fishing deck machinery. To assure the safety and dependability of these fishing deck machinery, calculations, simulation and functional tests are needed. This paper discusses the prediction of structural failure in the design of fishing deck machinery a hydraulic type with finite element method simulation approach. The results of the FEM simulation analysis are (i) the maximum value of von-Mises stress is greater than the ultimate tensile strength of the material; (ii) 1st principal stress value minimum is smaller than the ultimate tensile strength of material; (iii). the Poisson ratio value higher than the Poisson ratio value of the material. Base on the simulation result, the structural design of fishing deck machinery is safety.

Monte Carlo comparison of estimation methods for the two-parameter lognormal distribution

In the paper we compare performance of estimation methods for the two-parameter lognormal distribution via the Monte Carlo simulation. The comparison of performances is made with respect to their biases, variances, root mean square error. The methods are applied on real data set representing experimentally obtained values of ultimate tensile strength of material.

Probabilistic sensitivity analysis for the frame structure of missiles

In this study, the high-performance and high-reliability of missiles were achieved under the background of the probabilistic analysis for frame structure of missiles. On the basis of deep investigation of the artificial neural network method and mathematical model of multiorder moment method, artificial neural network based higher order moment approach was proposed for the probabilistic analysis of complex structure. As illustrated in frame structure probabilistic analysis with multiphysics fields based on artificial neural network based higher order moment, the reliability and failure probability of frame structure were studied. Furthermore, it was shown that the radial concentrated force P and the outer radius of the frame R2 are the most important factors, and the inside radius of the frame R1 and the ultimate tensile strength of materials σ b also have an important influence on the frame structure. Through comparison with Monte Carlo simulation, second-order fourth-moment approach and the artificial neural network based first-order second-moment approach, it was demonstrated that artificial neural network based higher order moment reshapes the possibility of complex aero-missile probabilistic analysis and improves computing efficiency while preserving the accuracy. Artificial neural network based higher order moment offers a useful insight for missile reliability design and optimization with multi-discipline. The efforts of this study also enrich the theory and method of mechanical reliability design.

Properties of lap welds in low carbon galvanized steel produced by tool assisted friction welding

Linear lap welds in very thin plates of galvanized steel were produced using tool assisted friction welding, a friction stir welding related technique. The morphological and microstructural analysis of the welds produced with varying tool rotational speed (up to 1400 rpm), tool traverse speed (up to 1200 mm/min) and tool diameter (10–16 mm) revealed the absence of stirred material or important welding defects in most of the joints. For the welds produced with the higher tool traverse and rotational speeds, a strong asymmetry in the weld morphology was also observed. A change in the contact conditions between the tool and the workpiece, from sticking to sliding, is appointed as the main factor responsible for the asymmetry in the weld morphology. The asymmetry in welds morphology has important influence in the failure mode of the welds in lap shear test but no influence on the joint strength. Lap shear strengths similar to base material ultimate tensile strength were measured for most of the welds.

Fabrication and Characterization of AA7075 Metal Matrix Composite Reinforced With MWCNT

Many engineering applications requires components with light weight property as well as good mechanical properties, this requirement can be served by the Metal Matrix Composites (MMCs) of Aluminum due to its outstanding performance. In the current research work an attempt has been made to fabricate the Aluminum metal matrix composite by liquid route i.e. stir casting. Aluminum Alloy (AA) 7075 is used as a matrix which is reinforced with Multi Walled Carbon Nanotubes (MWCNT) with varying percentage (0wt%, 0.25wt%, 0.5wt%, 0.75wt%). Experiments were carried out to analyze microstructure, micro hardness and the other mechanical properties like tensile strength and Impact strength. Also the samples were studied under Optical microscope and Scanning Electron Microscope (SEM) to investigate the dispersion of MWCNT in AA7075. Microscopic study of 0.25wt%, 0.5wt% & 0.75wt% samples shows a good dispersion of MWCNT into AA7075. Hardness of material increases by 6%, 12% and 25% for 0.25wt%, 0.5wt%, 0.75wt% respectively thus hardness increase with increase of MWCNT percentage. Ultimate tensile strength of material increases with increase in percentage of MWCNT and%Elongation reduces. Impact strength of material increases with increase in percentage of MWCNT.

On the fatigue strength of 3D-printed polylactide (PLA)

This paper aims to review quantitatively our understanding of the fatigue behavior of additively manufactured (AM) polylactide (PLA). A number of data sets were selected from the technical literature and statistically re-analyzed in terms of S-N curves to define a reference value both for the negative inverse slope and the endurance limit extrapolated at 2·106 cycles to failure. The experimental results being post-processed suggest that, as far as AM PLA is concerned, the mean stress effect in fatigue can be modelled by simply using the maximum stress in the cycle. Further, since the printing direction appears to have little effect on the overall fatigue behavior of AM PLA, the stress/strength analysis can be performed effectively by treating this polymer as a homogenous, isotropic and linear-elastic material. According to the statistical re-analysis discussed in the present paper, when appropriate experimental results cannot be generated, the fatigue assessment (for a probability of survival larger than 95%) can be performed by using a reference fatigue curve with negative inverse slope equal to 5.5 and endurance limit (at 2·106 cycles to failure) equal to 10% of the material ultimate tensile strength.

Explosion welding of Al + Cu bimetallic joints for electrical contacts

The manufacture of aluminium + copper electrically conducting bimetallic materials for electrical contacts and adapters by explosion welding was investigated. It is shown that the damping layer can be used efficiently for the protection of the surface of the flyer plate in the manufacture of the M1 + AD1 bimetal. The conditions of explosion welding of the bimetal using an explosive substance consisting of a mixture of porous ammonium nitrate with diesel fuel at a ratio of 96:4 are investigated. The effect of the structure on the physical and mechanical characteristics of the bimetallic material (ultimate tensile strength, shear and bending resistance, specific electrical conductivity) is studied.