Influence of the mechanical properties of materials on the ultimate pressure-bearing capability of a pressure-preserving controller

The pressure-preserving controller is the core part of deep in-situ pressure-preserving coring(IPP-Coring) system, and its pressure-preserving capability is the key to IPP-Coring technology. To achieve a good understanding of the influence of mechanical properties of materials on the ultimate pressure-bearing capability(UPB-Capability) of the pressure-preserving controller, the IPP-Coring experimental platform was developed to test the UPB-Capability of pressure-preserving controllers of four different materials. The experimental results show that the UPB-Capability of pressure-preserving controllers with different material varies greatly. A numerical model of the pressure-preserving controller was developed to study the influences of mechanical parameters of materials on the UPB-Capability of the pressurepreserving controller after the accuracy of the numerical model is verified by experiments. The results indicate that the yield strength(YS) and Poisson's ratio(PR) of the material have little effect on the UPB-Capability of the pressure-preserving controller, whereas the elastic modulus(EM) of the material has a significant effect. A generalized model of the UPB-Capability of the pressure-preserving controller is developed to reveal the mechanism of the influence of material properties on the UPB-Capability of the pressure-preserving controllers. Considering these results, the future optimization direction of the pressure-preserving controller and material selection scheme in practical engineering applications of the pressure-preserving controller are suggested.

Three-dimensional limit variation analysis on the ultimate pullout capacity of the anchor cables based on the Hoek-Brown failure criterion

Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass.The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method.The numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in advance.The results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.

Effects of cement-enhanced soil on the ultimate lateral resistance of composite pile in clayey soil

The composite pile consisting of core-pile and surrounding cement-enhanced soil is a promising pile foundation in recent years.However,how and to what extent the cement-enhanced soil influences the ultimate lateral resistance has not been fully investigated.In this paper,the ultimate lateral resistance of the composite pile was studied by finite element limit analysis(FELA)and theoretical upper-bound analysis.The results of FELA and theoretical analysis revealed three failure modes of laterally loaded composite piles.The effects of the enhanced soil thickness,strength,and pile-enhanced soil interface characteristics on the ultimate lateral resistance were studied.The results show that increasing the enhanced soil thickness leads to a significant improvement on ultimate lateral resistance factor(N P),and there is a critical thickness beyond which the thickness no longer affects the N P.Increasing the enhanced soil strength induced 6.2%-232.6%increase of N P.However,no noticeable impact was detected when the enhanced soil strength was eight times higher than that of the natural soil.The maximum increment of N P is only 30.5%caused by the increase of interface adhesion factor(a).An empirical model was developed to calculate the N P of the composite pile,and the results show excellent agreement with the analytical results.

Ultimate Strength of Hull Perforated Plate Under Extreme Cyclic Loading

In this study, the influence of opening parameters on the ultimate strength of perforated plates subjected to extreme cyclic loading in the presence of material kinematic hardening and isotro pic hardening was analyzed. It is found that the ultimate strength of the perforated plates decreases rapidly and stabilizes in the first four cycles. Plates with oblong openings have a greater ultimate strength compared to plates with rectangular openings, while the relative strengthening ratio decreases over the duration of the cycle. The location of the openings is also an important parameter that affects the strength of the structure, as the plates with openings close to the edges in the longitudinal direction have higher strengths, while in the transverse direction the strengths are higher when the openings are close to the center. Among the three opening-strengthening methods compared, the Carling stiffener method maintains a better strengthening effect under cyclic loads for many periods.

Ultimate pit optimization with ecological cost for open pit metal mines

The ecological costs of open pit metal mining are quantified, which include lost value of direct eco-services, lost value of indirect eco-services, prevention and restoration costs, and cost of carbon emission from energy consumption. These ecological costs are incorporated in an iterative ultimate pit optimization algorithm. A case study is presented to demonstrate the influence of ecological costs on pit design outcome. The results show that it is possible to internalize ecological costs in mine designs. The pit optimization outcome shifts considerably to the conservative side and the profitability decreases substantially when ecological costs are accounted for.

Experimental study on ultimate flexural capacity of steel encased concrete composite beams

Based on the experimental study and inelastic theory, the ultimate flexuralcapacity of steel encased concrete composite beams are derived. The difference between steel encasedconcrete composite beams with full shear connection and beams with partial shear connection,together with the relationship between the inelastic neutral axis of steel parts and concrete parts,are considered in the formulae. The calculation results of the eight specimens with full shearconnection and the three specimens with partial shear connection are in good agreement with theexperimental data, which validates the effectiveness and efficiency of the proposed calculationmethods. Furthermore, the nonlinear finite element analysis of the ultimate flexural capacity of thesteel encased concrete composite beams is performed. Nonlinear material properties and nonlinearcontact properties are considered in the finite element analysis. The finite element analyticalresults also correlate well with the experimental data.

Experimental research on ultimate bearing capacity of N-joints of grouted square steel tube trusses

Cave-in failure is apt to occur in joints of trusses made of square hollow sections. In order to turn the failure mode into a strength failure mode of joint members, the idea is proposed that the chord of the truss is grouted to increase the cave-in beating capacity of a hollow tube chord. An experiment of eight specimens of N- joints made of grout-filled square steel tubes is performed. Based on the experimental study, the geometrical parameters of specimens are analyzed, and the effects of the confinement index ε, the spacing between the two web members g and the ratio of side length of the vertical web member to that of the chord β on the behavior of specimens are investigated through simulation analysis by simulation analyses, the mechanical properties and the failure an ANSYS program. Based on the test results and modes of this kind of joints are analyzed and the formulae to predict the ultimate bearing capacities corresponding to different failure modes are developed. The ultimate bearing capacity of compressive N-joints is calculated in accordance with the cave-in failure mode of a chord member; the ultimate bearing capacity of tension N-joints is calculated in accordance with the punchingshear failure mode; the ultimate bearing capacity of a chord member is calculated in accordance with the shear failure mode in normal sections.

Influence of dent on residual ultimate strength of 2024-T3 aluminum alloy plate under axial compression

Drop-weight impact tests were conducted on 2024-T3 aluminum plates with five types of impactors, and then the effects of the dent on the residual ultimate strength of the 2024-T3 specimens were investigated through axial compression tests. Results indicate that with increase in dent depth, the five types of dents affect the ultimate strength of the plate in different trends. Nevertheless, other than the plate global deflection caused by impacting, the dent itself has unremarkable effect on the ultimate strength. The mathematical expressions are derived regarding the relationship between impact energy factor and the dent depth factor as well as the compressive ultimate strength reduction rate and the dent depth factor.

Lava Ultimate优韧瓷高嵌体修复无髓后牙牙体缺损的临床疗效

目的分析Lava Ultimate优韧瓷高嵌体修复无髓后牙牙体缺损的临床疗效。方法前瞻性选取2018年1月1日至2020年1月1日首都医科大学附属北京同仁医院诊治的无髓后牙牙体缺损患者62例。采用计算机随机数字分组法将其分成对照组和观察组,各31例。对照组患者接受Ceramage聚合瓷高嵌体修复,观察组患者接受Lava Ultimate优韧瓷高嵌体修复。比较两组患者临床疗效、咀嚼功能、牙龈反应及美观满意度。结果观察组患者临床总有效率为96.77%,高于对照组(77.42%),差异有统计学意义(P<0.05)。治疗前,两组患者咀嚼率比较,差异均无统计学意义(P>0.05);治疗6、12个月,观察组患者的咀嚼率为0.59±0.11、0.69±0.2,高于对照组(0.55±0.15、0.64±0.21),差异均有统计学意义(P<0.05)。治疗前,两组患者牙龈指数、菌斑指数比较,差异均无统计学意义(P>0.05);治疗后,观察组患者牙龈指数、菌斑指数为1.08±0.21、1.03±0.17,均低于对照组(1.95±0.26、1.89±0.25),差异均有统计学意义(P<0.05)。观察组患者美观总满意率为96.77%,高于对照组(70.97%),差异有统计学意义(P<0.05)。结论Lava Ultimate优韧瓷高嵌体修复无髓后牙牙体缺损能提升临床治疗效果,促使咀嚼功能恢复,优化牙龈健康情况,建议使用。

Ultimate load bearing capacity evaluation of concrete beams subjected to freeze-thaw cycles

A theoretical prediction method based on the change of concrete material is proposed to evaluate the ultimate bending moment of concrete beams which have undergone freeze-thaw cycles （PTCs）. First, the freeze-thaw damage on concrete material is analyzed and the residual compressive strength is chosen to indicate the freeze-thaw damage. Then, the equivalent block method is employed to simplify the compressive stress-strain curve of the freeze-thaw damaged concrete and the mathematical expression for the ultimate bending moment is obtained. Comparisons of the predicted results with the test data indicate that the ultimate bending moment of concrete beams affected by FTC attack can be predicted by this proposed method. However, the bond-slip behavior and the randomness of freeze-thaw damage will affect the accuracy of the predicted results, especially when the residual compressive strength is less than 50%.

Incidence of Pitting Corrosion Wastage on the Hull Girder Ultimate Strength

The paper focuses on the assessment of the hull girder ultimate strength,combined with random pitting corrosion wastage,by the incremental-iterative method.After a brief review about the state of art,the local ultimate strength of pitted platings under uniaxial compression is preliminarily outlined and subsequently a closed-form design formula is endorsed in the Rule incremental-iterative method,to account for pitting corrosion wastage in the hull girder ultimate strength check.The ISSC bulk carrier is assumed as reference ship in a benchmark study,devoted to test the effectiveness of the incremental-iterative method,by a comparative analysis with a set of FE simulations,performed by Ansys Mechanical APDL.Four reference cases,with different locations of pitting corrosion wastage,are investigated focusing on nine combinations of pitting and corrosion intensity degrees.Finally,a comparative analysis between the hull girder ultimate strength,combined with pitting corrosion wastage,and the relevant values,complying with the Rule net scantling approach,is performed.Based on current results,the modified incremental-iterative method allows efficiently assessing the hull girder ultimate strength,combined with pitting corrosion wastage,so revealing useful both in the design process of new vessels and in the structural health monitoring of aged ships.

Ultimate两通接头技术在气质联用仪中的应用

文中论述了Ultimate两通接头技术在气质联用仪中的数种应用情况,针对气质联用仪分析时常见的放空周期长,色谱柱间切换步骤繁琐、分析复杂基质时色谱柱易污染易堵塞等问题,提出了用Ultimate两通接头技术进行解决的方法。

Lava Ultimate优韧瓷髓腔固位冠在大面积牙体缺损短冠磨牙修复中的应用观察

目的观察Lava Ultimate优韧瓷髓腔固位冠在大面积牙体缺损短冠磨牙修复中应用效果。方法大面积牙体缺损短冠磨牙85颗,分为Lava Ultimate优韧瓷髓腔固位冠组(优韧瓷组)40颗、氧化锆髓腔固位冠组(氧化锆组)45颗,分别采用Lava Ultimate优韧瓷、氧化锆髓腔固位冠修复。修复后12个月对两组髓腔固位冠修复体进行临床效果评价,包括修复体完整性、修复体松动及脱落、边缘适合性、边缘着色、继发龋和牙龈健康状况,计算临床成功率。修复后12个月进行满意度调查,包括修复体颜色、外形、咀嚼功能和舒适度4个方面。离体短冠恒磨牙20颗,制作Lava Ultimate优韧瓷以及氧化锆髓腔固位冠修复体各10个,分别记为LU组、ZrO2组,制作硅橡胶间隙印模后,观察修复体边缘适应性(M1点值)和内部适应性(M2、M3及M4点值)。结果优韧瓷组和氧化锆组的髓腔固位冠修复体边缘密合,无边缘着色及继发龋的发生。优韧瓷组在修复后12个月出现1例修复体咬合面破损、1例牙龈轻微炎症,临床成功率为95.0%;氧化锆组在修复后12个月时出现1例修复体脱落、2例牙龈轻微炎症,临床成功率为93.3%,两组临床成功率相比,P>0.05。优韧瓷组患者在修复体舒适度的满意率高于氧化锆组(P<0.05)。LU组M1、M2、M3、M4点间隙值均小于ZrO2组(P均<0.05)。结论与氧化锆相比,Lava Ultimate优韧瓷髓腔固位冠修复大面积牙体缺损短冠磨牙疗效相当,但患者舒适度更高,且Lava Ultimate优韧瓷髓腔固位冠修复体的边缘适应性和内部适应性均更优。

SIMPLIFIED ANALYSIS METHOD FOR ULTIMATE LOAD CAPACITY OF WEB PLATES OF BOX GIRDERS

The prosperous post buckling load capacity of web plates of box girders can be used.In this article,the post buckling behaviour of web plates of box girders under different loading conditions is theoretically analyzed and on the basis of domestic and overseas design codes of steel structures,the corresponding simplified analysis methods are put forward for the engineering design or code revision.It is proved that the simplified methods are safe,efficient and practicable through the comparison between several results.

A deep-learning-based prediction method of the estimated ultimate recovery(EUR)of shale gas wells

The estimated ultimate recovery(EUR)of shale gas wells is influenced by many factors,and the accurate prediction still faces certain challenges.As an artificial intelligence algorithm,deep learning yields notable advantages in nonlinear regression.Therefore,it is feasible to predict the EUR of shale gas wells based on a deep-learning algorithm.In this paper,according to geological evaluation data,hydraulic fracturing data,production data and EUR evaluation results of 282 wells in the WY shale gas field,a deep-learning-based algorithm for EUR evaluation of shale gas wells was designed and realized.First,the existing EUR evaluation methods of shale gas wells and the deep feedforward neural network algorithm was systematically analyzed.Second,the technical process of a deep-learning-based algorithm for EUR prediction of shale gas wells was designed.Finally,by means of real data obtained from the WY shale gas field,several different cases were applied to testify the validity and accuracy of the proposed approach.The results show that the EUR prediction with high accuracy.In addition,the results are affected by the variety and number of input parameters,the network structure and hyperparameters.The proposed approach can be extended to other shale fields using the similar technic process.

Variation analysis of ultimate pullout capacity of shallow horizontal strip anchor plate with 2-layer overlying soil based on nonlinear M-C failure criterion

Based on the nonlinear Mohr-Coulomb failure criterion and an associated flow rule,a kinematic admissible velocity field of failure mechanism of the 2-layer soil above a shallow horizontal strip anchor plate is constructed.The ultimate pull-out force and its corresponding failure mechanism through the upper bound limit analysis according to a variation principle are deduced.When the 2-layer overlying soil is degraded into single-layer soil,the model of ultimate pullout force could also be degraded into the model of single-layer soil.And the comparison between results of single-layer soil variation method and those calculated by rigid limit analysis method proves the correctness of our method.Based on that,the influence of changes of geotechnical parameters on ultimate pullout forces and failure mechanism of a shallow horizontal strip anchor with the 2-layer soil above are analyzed.The results show that the ultimate pull-out force and failure mechanism of a shallow horizontal strip anchor with the 2-layer soil above are affected by the nonlinear geotechnical parameters greatly.Thus,it is very important to obtain the accurate geotechnical parameters of 2-layer soil for the evaluation of the ultimate pullout capacity of the anchor plate.

Ultimately exposed roof area prediction of bauxite deposit goaf based on macro joint damage

The ultimately exposed roof area(UERA)of goaf is crucial to the safety and economics of underground mining.The prediction models do not consider the mechanical weakness of rock mass and ignore the influence of the joint damage factor,causing a large predicted exposure area with a high roof falling risk.This work adopted joint damage factor to derive a new UERA prediction model.The relationships between the UERA(S)and the span ratio(m),the density(k)and the diameter of fracture(d)were analysed by the new prediction model.The results showed that the exposed area S and the span ratio m have a U-shaped curve relationship.The S decreases with the increase of m and then increases when m is beyond 2.The exposed roof area S is in an inversely proportional power-law relationship with the fracture surface density k,and the curvature of the S-k relationship curve decreases when d=0.5 and k>7,and S is close to 0.There is a negative correlation between S and the fracture surface diameter d,the curvature of the S-d curve decreases with the increase of d and k,and the variation rate increases first and then decreases with the increase of d;when k=0.5 and d>9,S is close to 0.The predicted values of the UERA prediction model are 119.3,112.8,and 114.6 m2 with different joint damage parameters,which are slightly smaller than the actual critical exposure area of a roof(S=120 m2).The case study shows that the alternative prediction model is reasonable and acceptable and provides new theoretical support for the underground mining safety of sedimentary bauxite ore.

Upper bound analysis of ultimate pullout capacity of shallow 3-D circular plate anchors based on nonlinear Mohr-Coulomb failure criterion

Based on the nonlinear Mohr-Coulomb failure criterion and the associated flow rules,the three-dimensional(3-D)axisymmetric failure mechanism of shallow horizontal circular plate anchors that are subjected to the ultimate pullout capacity(UPC)is determined.A derivative function of the projection function for projecting the 3-D axisymmetric failure surface on plane is deduced using the variation theory.By using difference principle,the primitive function of failure surface satisfying boundary condition and numerical solution to its corresponding ultimate pullout capacity function are obtained.The influences of nonlinear Mohr-Coulomb parameters on UPC and failure mechanism are studied.The result shows that UPC decreases with dimensionless parameter m and uniaxial tensile strength increases but increases when depth and radius of plate anchor,surface overload,initial cohesion,geomaterial density and friction angle increase.The failure surface is similar to a symmetrical spatial funnel,and its shape is mainly determined by dimensionless parameter m;the surface damage range expands with the increase of radius and depth of the plate anchor as well as initial cohesion but decreases with the increase of dimensionless parameter m and uniaxial tensile strength as well as geomaterial density.As the dimensionless parameter m=2.0,the numerical solution of UPC based on the difference principle is proved to be feasible and effective through the comparison with the exact solution.In addition,the comparison between solutions of UPC computed by variation method and those computed by upper bound method indicate that variation method outperforms upper bound method.

Effect of Strain Rate on Ultimate Strength and Fractograph in Tungsten Alloy

The effect of strain rate on ultimate strength and fractograph was investigated for tungsten alloy with four different technologies. As the strain rate rises, the ultimate strength increases and morphology of fracture surface gradually transits from detachment of interface between W pellets and matrices to cleavage of W pellets. Meanwhile, low strength tungsten alloy has higher sensitivity to strain rate.

Approach for analyzing the ultimate strength of concrete filled steel tubular arch bridges with stiffening girder

A convenient approach is proposed for analyzing the ultimate load carrying capacity of concrete filled steel tubular (CFST) arch bridge with stiffening girders. A fiber model beam element is specially used to simulate the stiffening girder and CFST arch rib. The geometric nonlinearity, material nonlinearity, influence of the construction process and the contribution of prestressing reinforcement are all taken into consideration. The accuracy of this method is validated by comparing its results with experimental results. Finally, the ultimate strength of an abnormal CFST arch bridge with stiffening girders is investigated and the effect of construction method is discussed. It is concluded that the construction process has little effect on the ultimate strength of the bridge.