Tailoring Static Strength Performance of Metallic Stiffened Panels by Selective Local Sub-Stiffening

2006 ◽  
Author(s):  
Adrian Murphy ◽  
Damian Quinn Quinn ◽  
Paul Mawhinney ◽  
Mustafa Ozakca ◽  
Sjoerd van der Veen
Keyword(s):  
Static Strength ◽  
Strength Performance ◽  
Stiffened Panels

scholarly journals AEROSPACE STIFFENED PANEL INITIAL SIZING WITH NOVEL SKIN SUB-STIFFENING FEATURES

2012 ◽  
Vol 12 (05) ◽  
pp. 1250060 ◽  
Author(s):  
D. QUINN ◽  
A. MURPHY ◽  
C. GLAZEBROOK
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Crack ◽  
Local Stability ◽  
Static Strength ◽  
Stiffened Panel ◽  
Element Analysis ◽  
Stiffened Panels ◽  
Buckling Behavior ◽  
Buckling Coefficient

The introduction of skin sub-stiffening features has the potential to modify the local stability and fatigue crack growth performance of stiffened panels. Proposed herein is a method to enable initial static strength sizing of panels with such skin sub-stiffening features. The method uses bespoke skin buckling coefficients, automatically generated by Finite Element analysis and thus limits the modification to the conventional aerospace panel initial sizing process. The approach is demonstrated herein and validated for prismatic sub-stiffening features. Moreover, examination of the generated buckling coefficient data illustrates the influence of skin sub-stiffening on buckling behavior, with static strength increases typically corresponding to a reduction in the number of initial skin longitudinal buckle half-waves.

scholarly journals The influence of concrete shrinkage on durability of reinforced structural members

2015 ◽  
Vol 63 (1) ◽  
pp. 15-22 ◽  
Author(s):  
K. Flaga
Keyword(s):  
Static Strength ◽  
Structural Members ◽  
Concrete Technology ◽  
Limit States ◽  
Important Distinction ◽  
Near Surface ◽  
Strength Performance ◽  
Concrete Shrinkage ◽  
Novel Approach ◽  
Macro Scale

Abstract The aim of the paper was to present the author’s novel approach to the problem of the influence of concrete shrinkage on the static-strength performance of reinforced structures. The problem of concrete shrinkage has been known in concrete technology for years, mainly in the theoretical and experimental aspects. However, there are few works in which the effect of concrete shrinkage in real reinforced structural members and structures is shown. In the present article the author performs an analysis of these effects on a macro-scale, useful in the assessment of the influence of concrete shrinkage on limit states of bearing capacity and serviceability of reinforced concrete structures. An important distinction is made between shrinkage stresses imposed in RC members by external and internal (reinforcement induced) constraints and residual shrinkage stresses inside members (massive especially) resulting from non-stationary and non-linear moisture fields. The article concludes with a way of calculating the necessary, near-surface anti-shrinkage reinforcement in such members.

ALCOA 7150-T7751 and T77511

Alloy Digest ◽  
2015 ◽  
Vol 64 (4) ◽  
Keyword(s):  
Compressive Strength ◽  
Corrosion Resistance ◽  
Tensile Properties ◽  
High Strength ◽  
Static Strength ◽  
Corrosion Resistant ◽  
Overaged Condition

Abstract This producer has pioneered the development of the -T77 temper, a high strength corrosion resistant temper for Alloy 7150 plate and extrusions. Alloy 7150-T77 provides weight savings opportunities in structure governed by static strength requirements but where "overaged" condition corrosion resistance is required. This datasheet provides information on composition, tensile properties, and compressive strength. It also includes information on corrosion resistance as well as forming. Filing Code: Al-442. Producer or source: Alcoa Mill Products Inc..

scholarly journals The use of flat-ended projectiles for determining dynamic yield stress - II. Tests on various metallic materials

1948 ◽  
Vol 194 (1038) ◽  
pp. 300-322 ◽  
Keyword(s):  
Yield Strength ◽  
Dynamic Strength ◽  
Soft Materials ◽  
Static Strength ◽  
Compressive Yield Strength ◽  
Dynamic Tests ◽  
Pure Lead ◽  
Permanent Strain ◽  
Yield Values ◽  
Static Conditions

A description is given of the experimental technique devised to apply the method outlined theoretically in part I to the measurement of the dynamic compressive yield strength of various steels, duralumin, copper, lead, iron and silver. A polished piece of armour steel was employed as a target, and cylindrical specimens were fired at it at various measured velocities from Service weapons. The distance between the weapon and target was made short to ensure normal impact, and apparatus was devised for the precise measurement of striking velocity over this short range. The dynamic compressive yield strength was computed from the density of the specimen, the striking velocity, and from measurements of the dimensions of the test piece before and after test. Details are given of the accuracy of the various measurements, and of their effect on the values of yield strength. The method was found to be inaccurate at low and high velocities. For instance, with mild steel, satisfactory results were only obtainable within the range 400 to 2500 ft. /sec. The range of velocities within which satisfactory results could be obtained varied with the quality of the material tested, soft metals giving results within a much lower range than that necessary for harder materials. Because of its failure at low velocities, the method could not be employed to bridge the gap between static and dynamic tests. The rate of strain employed in the dynamic tests could not be measured, but was estimated to be of the order of 10,000 in. /in. /sec. With the materials tested little change of dynamic strength occurred within the range of striking velocities employed, probably because the rate of strain did not vary to any great extent with the striking velocity. Within the range of weapons available, that is, from a 0·303 in. rifle up to a 13 pdr. gun (calibre 3·12 in.), little change of dynamic strength occurred with alteration of the initial dimensions of the specimens, probably because the corresponding change of rate of strain was not large. In general, the dynamic compressive yield strength S was greater than the static strength Y represented by the compressive stress giving 0·2% permanent strain. For steels of various types, regardless of chemical composition and heat treatment, there was a relation between S / Y and the static strength Y , the ratio decreasing from approximately 3 when Y was 20 tons/sq. in. to 1 when Y was 120 tons/sq. in. A similar relation occurred with duralumin, S / Y varying from 2·5 at Y = 8 tons/sq. in. to 1·4 at Y = 25 tons/sq. in. Dynamic compressive yield values were obtained for soft materials such as pure lead, copper and Armco iron, which, under static conditions, gave no definite yield values. A plot of the unstrained length of the specimen X , expressed as X / L (where L = initial overall length), versus the final overall length L 1 , expressed as L 1 / L , was made for the various materials. Any specified value of X / L was associated with greater values of L 1 / L for the more ductile materials, such as copper and lead, than for the brittle materials, such as armour plate and duralumin.

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