Fracture Point Research Articles

Effect of coupling damage on fatigue behavior of 2198‐T8 aluminum‐lithium alloy thin sheet for fuselage

AbstractBased on fatigue experiment and digital image correlation (DIC) technique, the fatigue damage behavior and the failure mechanism of the 2198 aluminum‐lithium alloy thin sheet used for the fuselage were investigated. Firstly, the influence of hemispherical insert size, impact energy, and rivet hole size Φ on the fatigue performance was explored. Secondly, the axial strain distribution and crack propagation behavior of the coupling damaged specimen under the fatigue cyclic loading were characterized by DIC. The results are as follows: the axial strain along the dent path and the rivet hole section path indicates that there exists a competitive relationship between the discontinuity caused by the rivet hole and the dent damage under the fatigue load. For specimens impacted by the same insert, the critical local plastic strain rate for the transition point of the fatigue fracture is related to the rivet hole size Φ, and it increases with the rise of Φ. After the dent damage being quantified, the final fracture position could be determined by the numerical comparison method.

Identification of Initial Crack and Fracture Development Monitoring under Uniaxial Compression of Coal with High Bump Proneness

The rock burst proneness of coal is closely related to the coal mass structure. Therefore, the initial crack distribution of high burst proneness coal, its fracture development, and failure process under loading conditions are of great significance for the prediction of rock burst. In this study, high burst proneness coal is used to prepare experiment samples. The surface cracks of the samples are identified and recorded. The internal crack of the sample is detected by nuclear magnetic resonance (NMR) technology to determine the crack ratio of each sample. Then, 3D-CAD technology is used to restore the initial crack of the samples. Uniaxial compression test is carried out, and AE properties are recorded in the test. The stress-strain curve, the distribution of the fractural points within the sample at different stress states, and the relationship between ring count and stress are obtained. Results show that the stress-strain curves of high burst proneness coal are almost linear, to which the stress-ring count curves are similar. The distributions of fractural points in different bearing states show that the fracture points emerge in the later load stage and finally penetrate to form macrofracture, resulting in sample failure. This study reveals the initial crack distribution of coal with high burst proneness and the fracture development under bearing conditions, which provides a theoretical basis for the prediction technology of rock burst and technical support for the research of coal structure.

Comparison of Mechanical Resistance to Maximal Torsion Stress in Original and Nonoriginal or Compatible Prosthetic Implant Screws: An In Vitro Study.

Micromovements of the implant-abutment connection influence peri-implant bone preservation. The maximal torque after a cycle of implant prosthetic screw tightening using original components of different manufacturers and replicas produced by other companies is evaluated and quantified in this study. A total of 30 Mis Seven® standard platform implants and 30 interfaces were used, and 30 standard platform screws were tested, 10 Mis®, 10 Iconekt®, and 10 Exaktus®. The screws were tightened with an MIS® torquemeter until their respective fracture, and the fracture point was measured through the equipment's load cell, CS-Dental Testing Machine®. The screws were analyzed under an Olympus® SZ61 microscope. The fracture points were recorded and compared among all samples. To compare the mean values of the fracture torques, t-tests were performed using the reference values associated with each brand and the sample results. The variable “Place of Fracture” between the original Mis® brand and the Exaktus® replica compared to the Iconekt® replica presented a statistically significant difference (p < 0.001). When analyzing the variable “Fracture Torque,” although it was verified that the replica screws (Iconekt® and Exaktus®) had a lower maximum torque, 65.11 Nm and 62.89 Nm, respectively, compared to the original Mis® brand (70 Nm and 69 Nm), there were no statistically significant differences p > 0.05. Nonoriginal screws did not present different fracture resistances compared to the original Mis® brand screws. The fracture site of Iconekt® screws showed a different pattern compared to the other brands.

Damage Prediction and Evolution using Uncoupled Elastoplastic-Damage Lemaitre’s and Vaz’s Models

This paper presents the two uncoupled elastoplastic-damage models; uncoupled Lemaitre’s and Vaz’s damage models. The two models are implemented into the finite element ABAQUS software using user routine UMAT to analyze and predict damage and damage evolution. In the context of von-Mises yield criteria, damage variable and fracture indicator are predicted, in addition to the von-Mises stress and the effective plastic strain. Both the elastoplastic tangent operator and the return mapping procedure are formulated using the consistent formulation. Two cases have been analyzed; the first one is an axisymmetric notched bar, while the second case is a plane strain doubled notched plate. In addition to the aforementioned predictions, a parametric study is carried out to explore the effect of the damage denominator and damage exponent on the damage behavior. It is concluded that the two models succeeded in the prediction of the point of fracture, while the uncoupled Lemaitre's damage model gives a more efficient description of the damage band.

Effect of Two Brands of Glaze Material on the Flexural Strength and Probability of Failure of High Translucent Monolithic Zirconia.

(1) Background: The effect of glazing on the mechanical properties of monolithic high translucent zirconia is not well reported. Therefore, the purpose of this study was to evaluate the effect of glazing on the flexural strength of high translucent zirconia; (2) Methods: Ninety specimens were prepared from second-generation 3Y-TZP high translucent blocks and divided into three groups. Glaze materials were applied on one surface of the specimen and subjected to a four-point bending test and flexural stress and flexural displacement values were derived. Descriptive fractographic analysis of surfaces was conducted to observe the point of failure and fracture pattern.; (3) Results: Control-nonglazed (647.17, 1σ = 74.71 MPa) presented higher flexural strength values compared to glaze I (541.20, 1σ = 82.91 MPa) and glaze II (581.10, 1σ = 59.41 MPa). Characteristic strength (σƟ) from Weibull analysis also observed higher (660.67 MPa) values for the control specimens. Confocal microscopy revealed that glazed surfaces were much rougher than control surfaces. Descriptive fractographic analysis revealed that there was no correlation between the point of failure initiation and flexural strength; (4) Conclusions: The test results demonstrated that glazing significantly decreased the flexural strength and flexural displacement of the zirconia specimens.

Development of Knowledge-Based Engineering System for Structural Size Optimization of External Fixation Device

The development process of the knowledge-based engineering (KBE) system for the structural size optimization of external fixation device is presented in this paper. The system is based on algorithms for generative modeling, finite element model (FEM) analysis, and size optimization. All these algorithms are integrated into the CAD/CAM/CAE system CATIA. The initial CAD/FEM model of external fixation device is verified using experimental verification on the real design. Experimental testing is done for axial pressure. Axial stress and displacements are measured using tensometric analysis equipment. The proximal bone segment displacements were monitored by a displacement transducer, while the loading was controlled by a force transducer. Iterative hybrid optimization algorithm is developed by integration of global algorithm, based on the simulated annealing (SA) method and a local algorithm based on the conjugate gradient (CG) method. The cost function of size optimization is the minimization of the design volume. Constrains are given in a form of clinical interfragmentary displacement constrains, at the point of fracture and maximum allowed stresses for the material of the external fixation device. Optimization variables are chosen as design parameters of the external fixation device. The optimized model of external fixation device has smaller mass, better stress distribution, and smaller interfragmentary displacement, in correlation with the initial model.

Rituals, Collapse, and Radical Transformation in Archaic States Edited by Joanne M.A. Murphy. London: Routledge 2021. Pp. 242. $160. ISBN 9780367230265 (cloth).

<i>Rituals, Collapse, and Radical Transformation in Archaic States</i> Edited by Joanne M.A. Murphy. London: Routledge 2021. Pp. 242. $160. ISBN 9780367230265 (cloth).

Experimental Investigations on Charge Induction and Microseismic Characteristics of the Coal and Rock under Different Loading Rates

The research on charge induction and microseismic characteristics of coal and rock under different loading rates is of great significance for rockburst prediction. In this study, the coal and sandstone samples from the No. 11 mine of Pingdingshan Coal Mine are prepared. The charge induction and microseismic synchronous comprehensive monitoring system is built. The uniaxial compression tests of coal and sandstone samples under the different loading rates are conducted. The charge induction and microseismic signal characteristics in the deformation and fracture process of the coal and rock under the different loading rates are studied. The results show that, with the increase of loading rate, the compressive strength of the coal and rock samples increases and the time from the peak stress to instability failure becomes shorter. At the same loading rate, the softening failure stage time of coal is longer than that of sandstone. With the increase of loading rate, the duration of charge-induced signal and microseismic signal is longer and the events’ number and amplitude of charge signal and microseismic signal increase in the deformation and fracture process of the coal and rock. Before the instability failure, the charge-induced signal and microseismic signal have both synchronous and asynchronous signals, and the amplitude of charge-induced and microseismic signals in each channel is different, which is related to the distance from the position of each sensor to the fracture point of the sample. During the instability failure, the charge induction and microseismic signals of each channel are generated synchronously, and the signal amplitude reaches the maximum values of 50 pC and 6 × 10−3 m/s at the same time. With the increase of specimen stress, the dominant frequency of microseismic signals first increases and then decreases, while the amplitude of dominant frequency increases synchronously. The dominant frequency amplitude of microseismic signals is the largest in instability failure. With the increase of loading rate, the spectrum amplitude of microseismic signals changes little in the compaction stage, but the spectrum amplitude increases in other stages. At the same loading speed, the events’ number of the microseismic signal of coal samples after peak stress is more than that of sandstone samples, and the signal amplitude is also larger. However, the spectrum distribution range of microseismic signals of coal samples is wider than that of sandstone samples, and the spectrum amplitude of coal samples is lower than that of sandstone. With the increase of loading rate, the time of the first generation of high-amplitude signals is advanced, and the stress of specimen becomes smaller when the first generation of high-amplitude signals occurs. With the increase of loading rate, the duration of microseismic and charge signal is longer, and the mean square amplitude of charge signal is larger.

Effect of nano clay, nano-graphene oxide and carbon nanotubes on the mechanical and tribological properties of crosslinked epoxy nanocomposite.

The objective of this study is to investigate the effects of different nanoparticles as reinforcement in a polymeric matrix on the mechanical and tribological properties of the composite. The different particles including nanoclay (NC), nano-graphene oxide (NGO), and carbon nanotubes (CNT) with various weight percentages were incorporated into the epoxy matrix. Young’s modulus, ultimate tensile strength, strain at the fracture point, and the fracture toughness of nanocomposite samples were investigated. Besides, the tribological performance of these fabricated nanocomposites was evaluated and discussed. The results show that a significant change in the mechanical properties of the nanocomposites compared to the epoxy matrix. Also, the results reveal that the combination of NC with NGO improves the mechanical properties of graphene nanocomposites. It is found that adding NC to the NG/epoxy composite, may increase the fracture toughness up to 2 times as well as improve the ultimate tensile strength and strain at the fracture point. However, there was no significant change in Young’s modulus.

Identifying Key Sites of Green Infrastructure to Support Ecological Restoration in the Urban Agglomeration

The loss and fragmentation of natural space has placed tremendous pressure on green infrastructure (GI), especially in urban agglomeration areas. It is of great importance to identify key sites of GI, which are used to economically and efficiently restore urban ecological network. However, in the existing research, few scholars have explored the identification and application of GI key sites. Taking the Southern Jiangsu Urban Agglomeration as an example, based on the ecosystem service assessment and landscape connectivity analysis, we identified the multi-class key sites of GI in the study area by MSPA, InVEST model, MCR model, and Linkage mapper. The results showed that: (1) a total of 60 GI sources and 130 GI corridors were extracted. The ecological resources of the study area were densely distributed in the north and south and sparsely in the middle. (2) Three-hundred eighty GI key sites were identified, including 53 water ecological points, 251 ecological fracture points, and 76 ecological pinch points. The GI key sites we identified were large in number and widely distributed, yet were hardly included in the existing ecological protection policies. These key sites should be prioritized in GI planning and differentiated for management strategies, ensuring that limited land resources and public funds can be directed to where restoration is really needed. The present study provides land managers and urban planners with additional tools to better understand how to effectively restore and develop the ecosystems of urban agglomerations in the context of scarce land resources.

Influence of bone tissue regenerate on rigidity of fractures fixation

Based on experimental studies, an analytical method is proposed for an estimation of the influence of a regenerate of a bone fabric on rigidity of the system of osteosynthesis.&#x0D; A method for the experimental determination of displacements in the fracture region under the action of loads taking into account the regenerate has been developed and tested.&#x0D; A number of experiments were performed in compression, bending and torsion to determine the deformation characteristics of systems without regenerate and in its presence.&#x0D; The results of experiments related to the influence of bone regenerate formed during the fusion of fractures on the mechanical characteristics of the system "bone with a fracture - a means of fixation" are described. To assess the impact of bone regeneration, a method for studying the deformation of osteosynthesis systems using the method of modeling bone regeneration with a polymeric material with specified properties was developed and implemented.&#x0D; Using the stiffness condition, the expression for the calculation of permissible loads that do not lead to dangerous displacements of fracture points is obtained. The reduced deformations and permissible loads for the systems "bone with a fracture - a means of fixation" at different stages of bone tissue (ВT) regeneration under the action of compression, bending and torsion are calculated. It is established that the formed regenerate significantly increases the rigidity of the system "bone with a fracture - bone regenerate - a means of fixation", which increases the level of allowable loads on the extremities at different stages of treatment.&#x0D; Test and calculation data can be used to improve methods of treatment of damaged limbs in the intermediate and final stages of fracture fusion.

Association of Sodium-Glucose Cotransporter–2 Inhibitors With Fracture Risk in Older Adults With Type 2 Diabetes

Whether sodium-glucose cotransporter-2 inhibitors (SGLT-2i) are associated with an increased risk of fractures in older adults with type 2 diabetes (T2D) outside of clinical trials remains unknown. To examine the association of incident fracture among older adults with T2D with initiating an SGLT-2i compared with initiating a dipeptidyl peptidase 4 inhibitor (DPP-4i) or a glucagon-like peptide 1 receptor agonist (GLP-1RA). This is a population-based, new-user cohort study including older adults (aged ≥65 years) with T2D enrolled in Medicare fee-for-service from April 2013 to December 2017. Data analysis was performed from October 2020 to April 2021. New users of an SGLT-2i, DPP-4i, or GLP-1RA without a previous fracture were matched in a 1:1:1 ratio using 3-way propensity score matching. The primary outcome was a composite end point of nontraumatic pelvic fracture, hip fracture requiring surgery, or humerus, radius, or ulna fracture requiring intervention within 30 days. After 3-way 1:1:1 propensity score matching, multivariable Cox proportional hazards regression models were used to generate hazard ratios (HRs) for SGLT-2i compared with DPP-4i and GLP-1RA and Kaplan-Meier curves to visualize fracture risk over time across groups. Of 466 933 new initiators of study drugs, 62 454 patients were new SGLT-2i users. After 3-way matching, 45 889 (73%) new SGLT-2i users were matched to new users of DPP-4i and GLP-1RA, yielding a cohort of 137 667 patients (mean [SD] age, 72 [5] years; 64 126 men [47%]) matched 1:1:1 for analyses. There was no difference in the risk of fracture in SGLT-2i users compared with DPP-4i users (HR, 0.90; 95% CI, 0.73-1.11) or GLP-1RA users (HR, 1.00; 95% CI, 0.80-1.25). Results were consistent across categories of sex, frailty (nonfrail, prefrail, and frail), age (<75 and ≥75 years), and insulin use (baseline users and nonusers). In this nationwide Medicare cohort, initiating an SGLT-2i was not associated with an increased risk of fracture in older adults with T2D compared with initiating a DPP-4i or GLP-1RA, with consistent results across categories of frailty, age, and insulin use. These findings add to the evidence base evaluating the potential risks associated with SGLT-2i use for older adults outside of randomized clinical trials.

J and CTOD-Based Tensile Strain Capacity Prediction for Pipelines With a Surface Crack in Girth Weld

Abstract Long-distance pipelines for the transport of oil and natural gas to onshore facilities are mainly fabricated by girth welding, which has been considered as a weak location for cracking. Pipeline rupture due to crack initiation and propagation in girth welding is one of the main issues of structural integrity for a stable supply of energy resources. The crack assessment should be performed by comparing the crack driving force with fracture toughness to determine the critical point of fracture. For this reason, accurate estimation of the crack driving force for pipelines with a crack in girth weld is highly required. This paper gives the newly developed J-integral and crack-tip opening displacement (CTOD) estimation in a strain-based scheme for pipelines with an internal surface crack in girth weld under axial displacement and internal pressure. For this purpose, parametric finite element analyses have been systematically carried out for a set of pipe thicknesses, crack sizes, strain hardening, overmatch, and internal pressure conditions. Using the proposed solutions, tensile strain capacities (TSCs) were quantified by performing crack assessment based on crack initiation and ductile instability and compared with TSCs from curved wide plate tests to confirm their validity.

Ecological network construction and optimization in Foshan City, China

Under the background of rapid urbanization, the problem of fragmented habitat patches in economically developed areas is particularly prominent, where biodiversity is seriously threa-tened. Therefore, the construction of ecological network is an important measure to connect habitat patches and protect biological habitats. We extracted ecological source areas of Foshan City by using the connectivity index and morphological spatial pattern analysis (MSPA). Potential ecological corridors were identified based on InVEST model and minimal cumulative resistance (MCR). Combining the radiation channels extracted from hydrological analysis to build an ecological network in Foshan City. The ecological network was optimized by adding ecological source areas, stepping stones, and identifying fracture points. Finally, the network before and after optimization was evalua-ted from the aspects of both structure and function based on network analysis method and circuit theory. The results showed that ecological network in Foshan City was composed of 10 ecological source areas, 8 important corridors, 37 general corridors, and 11 radiation channels. After optimization, 7 new ecological source areas, 17 planning corridors, 13 stepping stones, and 80 fracture points were added. After optimization, the ecological network closure, the line rate index and the connection degree index were 0.59, 1.94, and 0.73, respectively. The maximum current density increased from 1.39 to 9.66 after optimization, indicating that the optimized ecological network structure was more perfect and highly connective.

On low cycle fatigue of austenitic steel. Part II: Extraction of information on microcrack density from a combination of the acoustic and eddy current data

Microstructural information on damage in a metastable austenitic steel developed under low-cycle fatigue conditions is extracted from the acoustic monitoring of Poisson's ratio supplemented by the eddy current, and, under certain conditions, specific weight data. These data imply that damage has the form of мicropores of strongly oblate, crack-like shapes (aspect ratios of 0.01–0.04). This means that crack density – and not porosity – is the proper parameter of their concentration, in whose terms the effective properties should be expressed. It is also found that the microcrack density at the fracture point is proportional to relative volume of the strain-induced martensite. We also discuss relations between porosity and crack density.

A Novel Flow Model of Strain Hardening and Softening for Use in Tensile Testing of a Cylindrical Specimen at Room Temperature.

We develop a new flow model based on the Swift method, which is both versatile and accurate when used to describe flow stress in terms of strain hardening and damage softening. A practical issue associated with flow stress at room temperature is discussed in terms of tensile testing of a cylindrical specimen; we deal with both material identification and finite element predictions. The flow model has four major components, namely the stress before, at, and after the necking point and around fracture point. The Swift model has the drawback that not all major points of stress can be covered simultaneously. A term of strain to the third or fourth power (the “second strain hardening exponent”), multiplied and thus controlled by a second strain hardening parameter, can be neglected at small strains. Any effect of the second strain hardening exponent on the identification of the necking point is thus negligible. We use this term to enhance the flexibility and accuracy of our new flow model, which naturally couples flow stress with damage using the same hardening constant as a function of damage. The hardening constant becomes negative when damage exceeds a critical value that causes a drastic drop in flow stress.

Cutting parameters in dies for sheet metal through inclined, concave, and convex shapes in round punches

In this article, the punching in the die-making branch is analyzed based on the mechanical presses for punch cutting, and it is explained from its components and characteristics for sheet metal cutting. A relation is made in the cutting processes with each one of the proposed punches, and it is also shown that the material reaches a point of fracture with a value of 549.172 MPa, which details a better quality in the concave and inclined punch. Having cutting sections per side also allows for greater deformation. Also, the capacity to generate cut, in case of the concave of 0.5763 mm mm-1 with a cutting effort of 560.51 MPa and with the inclined punch, besides a deformation capable of generating cut of 0.40143 mm mm-1 with a maximum cutting effort of 570.3 MPa. That is within the optimum limits for 3 mm sheet metal cuts with variations of the cutting forces between the processes of 12% less in the concave punch and 10.3% in the inclined punch in relation to the convex punch.

Micromechanical origins of remarkable elongation-to-fracture in AHSS TRIP steels via continuous bending under tension

Continuous bending under tension (CBT) is known to achieve elongation-to-failure well above that achieved under a conventional uniaxial simple tension (ST) strain path. However, the detailed mechanism for supplying this increased ductility has not been fully understood. It is clear that the necking that occurs in a typical ST specimen is avoided by constantly moving the region of plastic deformation during the CBT process. The volume of material in which the flow stress is greatest is limited to a moving line where the rollers contact the sheet and superimpose bending stress on the applied tensile load. Hence the condition of a large volume of material experiencing stress greater than the material flow stress, leading to strain localization during ST, is avoided. However, the magnitude of the contribution of this phenomenon to the overall increase in elongation is unclear. In the current set of experiments, an elongation to fracture (ETF) of 4.56x and 3.7x higher than ST was achieved by fine-tuning CBT forming parameters for Q&P 1180 and TBF 1180, respectively. A comparison of maximum local strains near the final point of fracture in ST and CBT sheets via digital image correlation revealed that avoidance of localization of plastic strain during CBT accounts for less than half of the increased elongation in the CBT specimens for two steels containing different amounts of retained austenite (RA). Geometrically necessary dislocation evolution is monitored using high-resolution EBSD (HREBSD) for both strain paths, indicating a lower hardening rate in the CBT samples in the bulk of the sheet, potentially relating to the cyclical nature of the stress in the outer layers of the sheet. Interestingly, the GND evolution in the center of the sheet, which does not experience the same amplitude of cyclic stress, follows the ST behavior more closely than the sheet edges. This appears to contribute to a precipitous drop in residual ductility for the specimens that are pulled in ST after partial CBT processing. The rate of transformation of RA is also tracked in the steels, with a significantly lower rate of transformation during CBT, compared to ST. This suggests that a slower transformation rate achieved under CBT also contributed to higher strain-to-failure levels.

Fixation at the Inferior Orbital Rim in Medially Rotated Zygomatic Complex Fractures.

Background:Zygomatic complex fractures are quadri-pod fractures because of the involvement of the zygomaticotemporal, zygomaticomaxillary, zygomaticofrontal, and zygomaticosphenoid junctions. The need to address one or more fixation points of these four articulations mainly depends on the degree of displacement. In this article, the authors present a series of medially rotated zygomatic complex fractures to demonstrate that one-point fixation at the inferior orbital rim (IOR) is sufficient in most cases.Methods:This is a retrospective study of all medially rotated zygomatic complex fractures treated by the authors over the last 4 years.Results:The patients were six men with a mean age of 41 years. All patients sustained medially rotated zygomatic complex fractures. Three patients had symptomatic orbital floor defects. One patient had concurrent displaced superior orbital rim fracture. Surgery was done using the transconjunctival approach. A titanium mesh was used to fix the IOR. For orbital floor reconstruction, the same titanium mesh was extended into the floor to cover the defect. The patient with concurrent superior orbital rim fracture required a second point of fixation at the lateral orbital rim.Conclusions:Single-point of fixation at the IOR is sufficient in most medially rotated zygomatic complex fractures as long as there is minimal displacement at other fracture points. Some of these patients may have symptomatic orbital floor defects. Simultaneous fixation of the IOR and orbital floor reconstruction may be done via a transconjunctival approach.

The Influence of Different Plasma Cell Discharges on the Performance Quality of Surgical Gown Samples.

An experimental study was performed on a low-density plasma discharge using two different configurations of the plasma cell cathode, namely, the one mesh system electrodes (OMSE) and the one mesh and three system electrodes (OMTSE), to determine the electrical characteristics of the plasma such as current–voltage characteristics, breakdown voltage (VB), Paschen curves, current density (J), cathode fall thickness (dc), and electron density of the treated sample. The influence of the electrical characteristics of the plasma fluid in the cathode fall region for different cathode configuration cells (OMSE and OMTSE) on the performance quality of a surgical gown was studied to determine surface modification, treatment efficiency, exposure time, wettability property, and mechanical properties. Over a very short exposure time, the treatment efficiency for the surgical gown surface of plasma over the mesh cathode at a distance equivalent to the cathode fall distance dc values of the OMTSE and for OMSE reached a maximum. The wettability property decreased from 90 to 40% for OMTSE over a 180 s exposure time and decreased from 90 to 10% for OMSE over a 160 s exposure time. The mechanisms of each stage of surgical gown treatment by plasma are described. In this study, the mechanical properties of the untreated and treated surgical gown samples such as the tensile strength and elongation percentage, ultimate tensile strength, yield strength, strain hardening, resilience, toughness, and fracture (breaking) point were studied. Plasma had a more positive effect on the mechanical properties of the OMSE reactor than those of the OMTSE reactor.