共查询到20条相似文献，搜索用时 31 毫秒
1.
S. B. Kasatkin 《Strength of Materials》1976,8(11):1346-1350
| 1. | Polycarbonate specimens enable direct observation of the stress-strain pattern during the loading process. |
| 2. | It has been shown that under plane strain and plane stress conditions the crack starts at the boundary of the elastic-plastic deformation zone at the moment when the normal stress component reaches the critical value. |
| 3. | Under plane strain conditions the value cr is determined by the yield point and the radius of the notch n. Under plane stress conditions the strip of plastic deformation functions, as a stress concentrator. Fracture occurs when the normal stress component at the boundary reaches the critical value. |
| 4. | During the intervals when the specimen is not loaded the plastically deformed zones act as concentrators of residual stress. When load is again applied there is interaction between the residual stresses and the externally induced stresses. |
2.
A. Ya. Krasovskii I. V. Orynyak A. V. Naumov V. N. Krasiko 《Strength of Materials》1989,21(6):697-702
| 1. | A computational model is proposed, and a general solution is obtained for equations describing the process of the impact testing of specimens in concentrated bending in the presence of supports, where the effect of the striker and support on the specimen is represented as the reaction of springs with flexibilities and , respectively. |
| 2. | The general solution for each of the force parameters assumes the form of the sum of two harmonic functions and a function that is linearly time-dependent. For large time values, therefore, the vibratory processes become negligibly small; this makes it possible to use the quasistatic approach, whose accuracy is proportional to the time to failure, to determine KId. |
| 3. | Experimental confirmation of the solutions obtained suggests that disregard of the flexibilities of the specimen halves in the computational model (shoulders of specimen) leads to a reduction in the computed vibration amplitude and period as compared with the experimental. The difference between the theoretical and experimental results increases as the ratio L/Lo increases and the ratio a/W decreases. |
3.
| 1. | Analytical relations were established which make it possible to determine the temperature Tb for standardized specimens. |
| 2. | It was shown that it is possible to use either of the known relations of(T) or KIc(T) and the value of Tb to find the other relation-say KIc(T). |
| 3. | The analytical expressions obtained in the present study for Tb agree qualitatively with the changes seen in practice in the quantity Tb under the influence of radiation due to a change in loading rate, variation of the geometry of the specimen and CSM, variation of the notch radius, or other factors. |
4.
| 1. | Singular elements with a notch of an arbitrary angle were constructed to determine the stress fields near through notches. |
| 2. | To increase the accuracy of the solution, we constructed transitional singular elements which increase the size of the region re in which singularity is modeled and decrease the incompatibility between the regular and notched singular elements. |
| 3. | A procedure was developed for determining the stress field near notches under dynamic loadings. |
| 4. | The stress intensity factor near small-angle notches differs negligibly from the stress intensity factor near cracks of the same length under static and dynamic loadings. |
| 5. | The finite elements that were constructed make it possible to reliably solve linear fracture mechanics problems by the finite elements method with the use of very coarse idealizations. |
5.
M. N. Georgiev N. Ya. Mezhova E. M. Morozov V. A. Reikhart 《Strength of Materials》1988,20(9):1133-1138
| 1. | It was establised that crack resistance limit Ic determined in full-profile nonheat-treated rails with cross fatigue cracks of area 10...30% of the rail head cross-sectional area is practically constant. The breaking stress c in all the cases is lower than the elastic limit c of the materials, in view of which, its crack resistance limit can be considered as a critical coefficient of the stress intensity for a plane deformed state, i.e., IcKIc. |
| 2. | For the non-heat-treated rails P65 with cross fatigue cracks (defect-21) KIc=37.5 MPa m. |
| 3. | The KIc values determined in full-profile non-heat-treated rails with cross fatigue cracks of area 10...30% of the rail head cross-sectional area practically does not differ from the results obtained as per GOST 25.506-85 in specimens taken from the same rails. |
| 4. | The KIc values for the non-heat-treated rails P65 with cross fatigue cracks decrease on the average by 40% for a test temperature drop from –253 to –333°K. |
6.
Abstract and Key Results
相似文献
| • | This study explores the impact that formal and relational governance mechanisms have in inducing local suppliers to make transaction-specific investments in foreign and local manufacturers, respectively. |
| • | Analyses, in this regard, were based on a sample comprised of 77 local supplier/foreign manufacturer relationships and 57 local supplier/local manufacturer relationships in China. |
| • | The efficacy of different governance mechanisms, as shaped by local and foreign manufacturers, exerts varying degrees of impact on suppliers’ transaction-specific investments. |
7.
Christos Pitelis 《Management International Review》2007,47(2):207-219
| – | We apply insights from Edith Penrose’s work to extant theory of the multinational enterprise (MNE) as enveloped by John Dunning’s Ownership, Location, Internalization (OLI) Paradigm. |
| – | We suggest that Penrose’s knowledge/learning-based approach has important implications on the nature of, and the interactions between, O, L and I, and it helps endogenize and integrate the three elements of Dunning’s triad in the context of a dynamic, and strategic perspective of the MNE. |
| – | More importantly, a learning-based perspective adds a cognitive dimension to the MNE and OLI. |
| – | This supports a forward looking, synchronic decision making view, that may lead to apparently sub-optimal decisions, taken in view of anticipated changes, along-side strategic behaviour, aiming to effect such change, once decisions have been reached. |
| – | A Penrosean-inspired knowledge/learning-based perspective helps render the OLI more dynamic, strategic and forward looking. |
8.
| • | Both scholars and practitioners have paid much attention to the impact of retaining top-performing knowledge workers on organizational effectiveness. |
| • | This study hypothesizes and analyzes how a bundle of high-commitment human resource practices (HCHRPs) influence affective organizational commitment, a strong predictor of employee turnover, of top performers versus ordinary employees. |
| • | This study suggests that HCHRPs may enable organizations to retain not only ordinary employees but also top performers through their positive impact on employees’ organizational commitment. |
| • | Using a sample of middle level managerial and R&D workers in 11 subsidiaries of a multinational conglomerate located in East Asia, this study showed that a bundle of high commitment human resource practices was positively related to the affective organizational commitment of top performers more than that of lower performers. |
9.
| 1. | The fracture of heat-resistant alloys and tool steels under the influence of thermal cycling may be quasistatic, fatigue, or mixed in character. |
| 2. | Quasistatic fracture as a result of thermal cycling takes place with the specimen working portion remaining constant (hard loading mode); it is caused by the accumulation of strains of opposite signs in local material volumes. |
| 3. | The accumulation of residual strains in local specimen volumes for thermoplastic strain materials is due to the mismatch of plastic strain fields along the specimens during the heating and cooling cycles. |
| 4. | Under thermal cycling conditions (as in isothermal low-cycle fatigue) the static damage is measured in terms of the accumulated plastic strain (of a given sign), while the fatigue damage is measured in terms of the magnitude of the plastic strain per cycle. Quasistatic fracture takes place in regions of the maximum accumulated plastic strain which is equal to zero in the zone of fatigue fracture. |
10.
Aaron Gilbert Alireza Tourani-Rad Tomasz Piotr Wisniewski 《Management International Review》2007,47(5):745-766
Abstract and Key Results
相似文献
| • | Despite the importance of insider trading laws in promoting a strong financial market, the impact of regulations in minimizing the detrimental effects of insider trading is unsettled. |
| • | We add to the literature by examining the impact of the introduction of the Securities Market Amendment Act 2002 in New Zealand on several aspects of the market, namely bid-ask spreads, liquidity, price volatility and the cost of capital. |
| • | We find strong evidence of predicted reductions in the cost of capital, bid-ask spreads and volatility accompanied by increases in liquidity. We conclude that the change in regulations has had a positive impact on the market. |
11.
| • | This paper examines the impact of corporate governance and institutional environments on the export behaviour of firms in emerging economies. We argue that the role of corporate governance should be analysed from both principal- agent and principal-principal perspectives. We hypothesise that institutional environments moderate the effects of corporate governance on export behaviour. |
| • | Analysis of a sample of Chinese listed firms supports our argument that outside directors and CEO shareholding help firms make export decisions, while the effects of ownership concentration may be non-monotonic. |
| • | Sample firms’ export propensity is higher the better the institutional environments of their locations. This positive effect of institutional environments comes both directly and from the moderating of the effects of corporate governance. |
12.
N. M. Aptekar' S. L. Babchenko G. M. Vorob'ev G. V. Yashnaya O. D. Smiyan 《Materials Science》1976,11(6):650-652
| 1. | Selective absorption of hydrogen (at active centers) takes place on the working surface of railway crossing points made of steel G13L. |
| 2. | High hydrogen concentrations are found in the metal adjacent to exfoliation; these concentrations reach a maximum in layers situated at a distance of 0.5–1 mm from the exfoliation surface. |
| 3. | In an exfoliation zone the hydrogen concentrations are considerably greater than the initial values. |
| 4. | Splashes of hydrogen concentrations are observed in regions of the surface layers of the crossings in which flakes are not actually visible; the state of the metal can then be described as the preflaking stage. |
13.
V. T. Troshchenko V. V. Pokrovskii P. V. Yasnii V. G. Kaplunenko V. V. Burdakov V. P. Leonov Yu. A. Nikonov 《Strength of Materials》1988,20(9):1138-1145
| 1. | On the basis of the experimental investigation of the effect of the test temperature (153–293°K) on the rate of FCG in steels IP-1, IP-2, and IP-3 with a coefficient of load cycle asymmetry R=–2, –1, 0, and 0.5 it was established that lowering of the test temperature has an ambiguous effect on the rate of fatigue crack growth in the mentioned steels. In most cases the rate of FCG is practically insensitive to the test temperature although we can see a general tendency of the coefficient m of the Paris equation increasing with the test temperature being lowered from 293 to 153°K. |
| 2. | A change of the coefficient of load cycle asymmetry in the range –2–0 does not have a substantial effect on the rate of FCG, and in the range 0–0.5 it reduces this rate (in coordinates d/dN-Kmax) at 213 and 293°K, particularly substantially at 213°K. |
| 3. | For the investigated chrome-nickel-molybdenum steels in the temperature range 293-153°K a single dependence was established; it describes the decrease of the coefficient m with rising level of fracture toughness under static loading. |
| 4. | With the test temperature rising from 113 to 153°K, the characteristics of fracture toughness of all the investigated steels increase monotonically under static and cyclic loading, and also in the case of stopping of the crack. |
| 5. | Cyclic loading reduces substantially (to one half) the fracture toughness of steels IP-1 and IP-2 in the temperature range 113–153°K and does not change the values of K1 fc compared with KIc for steel IP-3. |
| 6. | In steels IP-1, IP-2 at temperatures of 113–153°K the fracture toughness under cyclic loading corresponding to final fracture of the specimen practically coincides with the fracture toughness at the instant of stopping of the crack. |
| 7. | In the temperature range 100–183°K of the three investigated steels steel IP-1 has the highest resistance to brittle failure under static loading and at the instant of stopping of the crack, steel IP-2 has the lowest resistance. |
14.
B. A. Kolachev 《Materials Science》1992,28(5):395-398
| 1. | A general method of improving the composition of the HSA by complex alloying has been proposed. |
| 2. | Systems of alloying the HSA on the basis of intermetallic compounds TiFe, TiCo, TiCr2, TiMn2 have been described and characterized. |
| 3. | It is shown that not all possibilities of complex alloying have been exhausted to improve the properties of the HSA based on titanium. |
15.
| 1. | In dependence on the strain-hardenability of material determined by the type of crystal lattice, the test temperature, by alloying and work-hardening, loss of stability may cause either strict localization of deformation in the neck or smooth transition from uniform deformation to concentrated deformation in static tension of a smooth cylindrical specimen. |
| 2. | In compression, torsion, bending, tension in a state of plane stress and other kinds of tests, the margin of strength of the part and its technological and design strength are determined chiefly by the magnitude of the ratio of yield strength to true tensile strength (and not ultimate tensile strength), and also by the magnitude of relative contraction, i.e., by parameters characterizing the capacity of material to the nucleation and development of flaws in it under plastic deformation. |
| 3. | Uniform deformation and the magnitude of the ratio 0.2/u play an important role in ensuring the load-bearing capacity of a structure, in particular, when cylindrical parts are subjected to tensile loads. In that case loss of stability of uniform deformation leads to reduced strength of the part, and essentially it is the onset of failure. |
16.
| a) | The study describes the basic fracture micromechanisms of porous materials with dominantly ferritic matrix structures. |
| b) | Quantitative fractography is used to describe the basic mechanisms of crack propagation in the porous body corresponding to the non-monotonous temperature dependence of fracture toughness values. |
| c) | Behavior of fracture toughness values and relevant fracture micromechanisms indicate that the state of plane deformation in microvolumes in front of the crack tip cannot be reached at higher porosities and temperatures. This piece of information corresponds to the knowledge of independence of fracture toughness values of porous materials on the specimen thickness, as is presented in the literature [5]. |
17.
Abstract and Key Results
相似文献
| • | This study discusses the underlying reasons for the variant nature of the relationship between multinationality and firm performance in the context of service firms. |
| • | To date, this line of research has mostly used evidence from manufacturing firms, despite the ever-increasing contribution of service firms to national and global economies. |
| • | We conduct an exploratory study using case analyses of large European retail banks. We argue that the nature of the multinationality-performance relationship for services is moderated by industry characteristics, market-based factors and firm-specific factors. |
| • | We conclude that the shape of the curve depicting the multinationality-performance relationship of retail banks experiences substantial variations on a single case level. |
| • | Our exploratory study of retail banks shows that the multinationality-performance relationship varies significantly depending on banks’ strategic decisions regarding branch network configurations, product portfolios, branding strategies, organizational architecture (HQ-subsidiary relationship), and social networks. Any generalization of the relationship is difficult and prone to error. |
18.
| 1. | Sheets of the Zr- 1% Nb alloy were used for the first time to show by experiments the crystallographic reorientation of the grains at the tip of the moving crack. |
| 2. | The effects detected by x ray diffraction examination in the vicinity of the fracture of the specimens with the notch, were compared with the effects recorded in the volume of similar smooth specimens subjected to tensile loading. According to the estimates, in the layer up to 20m thick, adjacent to the fracture surface, the average strain of the material in tensile loading is 15–20% for the RD specimen and 3–5% for the TD specimen. |
| 3. | Anisotropy of the cracking resistance and development of the zone of plastic deformation at the tip of the moving crack are determined by the activating mechanism of plastic deformation of alpha zirconium whose special feature is the strong dependence on the crystallographic orientation of the grains. |
19.
Toru Yoshikawa Abdul A. Rasheed Deepak K. Datta Joseph Rosenstein 《Management International Review》2006,46(5):529-555
Abstract and Key Results
相似文献
| – | ▪ Growing financial and product market integration has resulted in increased pressures for changes in most developed economies. We investigate the impact of these twin drivers on changes effected by Japanese firms between 1986 and 1999. |
| – | ▪ Specifically, we examine (1) how shareholdings by market investors and foreign investors and (2) export ratio impact outcomes in the form of efficiency increases, dividend payout, and leverage change. |
| – | ▪ We also investigate whether the relationships differ between keiretsu and nonkeiretsu firms. |
| – | ▪ Ownership by market investors was positively associated with efficiency increases and decreases in firm leverage. In addition, firm export ratio played a key role in motivating Japanese firms to increase their efficiency and firm leverage. Moreover, these relationships were more pronounced in non-keiretsu than keiretsu firms. |
20.
| 1. | Steel strengthened by phase work-hardening is distinguished by a ratio of fatigue limit to tensile strength (–1/u=0.55–0.60) significantly greater than that of dispersion hardening steel. |
| 2. | The surface treatment method (grinding, turning, surface plastic deformation to a definite intensity) does not have a significant effect on the fatigue strength of N26T steel strengthened by phase work-hardening. |
| 3. | Combined strengthening of phase work-hardenable steel by surface plastic deformation, which causes the formation of 15–25% phase on the surface, and subsequent aging at 350–400°C is an effective means of increasing life. The use of this method makes it possible to increase the fatigue limit by 20% for uniform cross section samples and by 200% for those with a notch. |
| 4. | The increase in the fatigue limit with the use of combined strengthening (surface plastic deformation and aging) is related to the increase in the strength of the surface layers as a result of the increase in the dislocation density and fixing of them by the particles of Ni3Ti precipitated in aging and also to the decrease in peak microstresses. |