Behavior of surface and corner cracks subjected to tensile and bending loads in Ti-6Al-4V alloy

The behavior of part-through flaws with regard to failure under monotonic loading and their growth under fatigue loading was studied experimentally and analytically. Comparisons are made of experimental values of toughness obtained using surface and corner cracked specimens with those obtained using standard test specimens, and also experimental growth cycles were compared with numerical predictions using the NASA/FLAGRO computer program. Tests were conducted on various types of surface and corner cracks under tensile and bending loads. Room temperature lab air provided the test environment. The material used in this study was the Ti-6Al-4V alloy in the solution treated and aged (STA) and stress relieved condition. Detailed tabulation of the fracture toughness data and results of life prediction using the NASA/FLAGRO program are presented. Fatigue crack growth rates for the part-through cracked specimens are compared with a base curve fitted from the data obtained using standard specimens. The fatigue loading used in the crack growth testing was constant-amplitude sinusoidal type

An evaluation of the fatigue crack growth and fracture toughness properties of beryllium-copper alloy CDA172

A series of fracture mechanics tests, using the Be-Cu alloy CDA172 in the round rod product form, was conducted in a lab air environment at room temperature. Tensile data is presented in both the L and C directions and K sub Ic data in both the C-R and C-L orientations. Fracture toughness values were derived from M(T) (center cracked), PS(T) (surface cracked) and CC01 (corner cracked) specimens of varying thickness. Fatigue crack growth data were obtained for the C-R orientation at stress ratio of 0.1, 0.4, and 0.7 and for the C-L orientation at stress ratios of 0.1, 0.3, 0.4, and 0.7

Data base for crack growth properties of materials

A computerized data base of crack growth properties of materials was developed for use in fracture control analysis of rocket engine components and other NASA space hardware. The software system has files of basic crack growth rate data, other fracture mechanics material properties such as fracture toughness and environmental crack growth threshold values, and plotting and fitting routines for deriving material properties for use in fracture control analysis. An extensive amount of data was collected and entered, and work is continuing on compiling additional data. The data base and software codes are useful both for fracture control analysis and for evaluation or development of improved crack growth theories

Resource estimation of information systems projects: A case study

Estimating resource requirements on any project is challenging and this is certainly the case for Information Systems (IS) projects. The impact of resource estimation of I/S projects has far reaching consequences, for the individual, the team, and the organization as a whole. In spite of its critical importance, estimating project resource requirements is still somewhat arbitrary and ad hoc in many organizations. Thjs paper presents a case study about a large insurance company and its efforts to develop aid implement a successful estimation model for IS projects. The impact of this methodology on productivity and cost savings is also outlined. Planed improvements to the current methodology are discussed

Plant specimens for identification

PLANT names and the naming of plant specimens are of fundamental importance in the science of botany. In applied botany as well, proper identification is of the utmost importance. In agriculture for instance, accuracy in naming poisonous plants and weeds, as well as fodder and pasture species, can save farmers considerable sums of money, and may be responsible for avoiding heavy stock losses

Pinin\u27 Just For You

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On the Crack Bifurcation and Fanning of Crack Growth Data

Crack growth data obtained from ASTM load shedding method for different R values show some fanning especially for aluminum alloys. It is believed by the authors and it has been shown before that the observed fanning is due to the crack bifurcation occurs in the near threshold region which is a function of intrinsic properties of the alloy. Therefore, validity of the ASTM load shedding test procedure and results is confirmed. However, this position has been argued by some experimentalists who believe the fanning is an artifact of the test procedure and thus the obtained results are invalid. It has been shown that using a special test procedure such as using compressively pre-cracked specimens will eliminate the fanning effect. Since not using the fanned data fit can result in a significantly lower calculated cyclic life, design of a component, particularly for rotorcraft and propeller systems will considerably be impacted and therefore this study is of paramount importance. In this effort both test procedures i.e. ASTM load shedding and the proposed compressive pre-cracking have been used to study the fatigue crack growth behavior of compact tension specimens made of aluminum alloy 2524-T3. Fatigue crack growth paths have been closely observed using SEM machines to investigate the effects of compression pre-cracking on the crack bifurcation behavior. The results of this study will shed a light on resolving the existing argument by better understanding of near threshold fatigue crack growth behavior

New danger from Hoary cress

HOARY CRESS is undoubtedly one of the worst weeds introduced into Australia. It is a vigorous deep rooted perennial which competes strongly with crop plants and seriously decreases yields. The importance of three recent discoveries of this weed in Western Australia therefore need hardly be stressed. G. R. W. Meadly, Offlcer-in-Charge of the Weeds and Seeds Branch, and R. D. Royce, Offlcer-in- Charge of the Botany Branch, report on two recently found infestations of hoary cross in the Great Southern, and one at Jerramongup. An intensive eradication programme is under way

Multiple unilateral craniopathies (Guillain-Alajouanine-Garcin syndrome) resulting from a malignancy of the external auditory canal: a case report

Garcin syndrome (or Gullain-Alajouanine-Garcin syndrome) was first described in the year 1926, as a paralytic unilateral cranial syndrome consisting of multiple cranial nerve palsies, without findings pointing towards increased intracranial pressure or long tract involvement. A 54-year-old female presented to us initially with ptosis and lateral rectus palsy of the right eye, later on, followed by progressive hearing loss on the right ear, right facial hemianesthesia, and progressive ipsilateral facial paralysis. A mass at the external auditory canal was seen during otoscopy, and a biopsy revealed squamous cell carcinoma. Contrast-enhanced neuroimaging also showed an enhancing mass lesion at the right skull base