Processes Controlling the Dynamic Fracture of Brittle Solids, (9999)
A brief summary of some experimental results on dynamic fracture of brittle solids is presented. A complete presentation of the various aspects of dynamic fracture is discussed. The experimental...
Viscoelastic Effect on Dynamic Crack Propagation in Homalite 100, (9999)
Kim,K. S., Dickerson,K. L., Knauss,W. G.
The optical method of caustics is used to determine the stress intensity factor for a running crack in a viscoelastic material. A formulation of the quasi-static deformation of materials with...
A new shear-compression-specimen for determining quasistatic and dynamic polymer properties (2009)
Zhao, J., Knauss, W. G., Ravichandran, G.
A new design of the shear compression specimen (SCS) for investigating the viscoelastic shear response of polymers is presented. The specimen consists of a polymer gage section with two metal ends...
Caltech Asci Technical Report 105 (2008)
S. B. Sane, T. Cagin, W. A. Goddard, W. G. Knauss
The results of molecular dynamics computations and corresponding values of laboratory measurements are compared to assess the efficacy of the numerical method. Details are presented on the modeling...
Zhao, J., Knauss, W. G., Ravichandran, G.
This paper addresses the applicability of the Time–Temperature Superposition Principle in the dynamic response of a polyurea polymer at high strain rates and different temperatures. Careful and...
Abstract Molecular Dynamics Simulations to Compute the Bulk Response of Amorphous PMMA (2007)
S. B. Sane, T. Cagin, W. A. Goddard, W. G. Knauss
The results of molecular dynamics computations and corresponding values of laboratory measurements are compared to assess the efficacy of the numerical method. Details are presented on the modeling...
The Mechanical Characterization of Solithane 113 in the Swollen and Unswollen State, (2005)
The following report divides into three parts. Part I summarizes the variation of material properties for several Solithane 113 formulations; part II amplifies on the mechanical behavior of a...
Application of Fracture Mechanics to Predicting Failures in Solid Propellants. (2005)
Francis, E. C., Carlton, C. H., Deverall, L. I., Lindsey, G. H., Knauss, W. G.
Analytical and experimental methods were developed to measure the structural and fracture properties of a linear elastic epoxy and a linear viscoelastic polyurethane material (Solithane). These...
On the Mechanical Properties of the Human Intervertebral Disc. (2002)
Panagiotacopulos,N. D., Bloch,R., Knauss,W. G., Harvey,P., Patzakis,M.
The human intervertebral disc is a highly inhomogeneous fiber composite pressure vessel. Interest in the mechanical properties of the disc started from a desire to develop a non-invasive diagnostic...
Fatigue Behavior of Adhesively Bonded Joints. Volume I. (2002)
The fatigue behavior of adhesively bonded aluminum joints was investigated analytically and experimentally. Stress distributions in the adhesive interlayer were calculated to guide planning of the...
Fatigue Behavior of Adhesively Bonded Joints. Volume II. Appendices. (2002)
The fatigue behavior of adhesively bonded aluminum joints was investigated analytically and experimentally. Stress distributions in the adhesive interlayer were calculated to guide planning of the...
Completion of construction of the loading device frame, tubes and speciment holders; development of suitable heating and cooling systems for the tubes; development of a method to measure the (small)...
Integrated Methodology for Adhesive Bonded Joint Life Predictions. (2002)
Romanko,John, Liechti,K. M., Knauss,W. G.
A comprehensive integrated methodology for adhesive bonded joint life predictions is outlined. While poorly made joints can fail at the adherend interface, properly made joints are far stronger,...
A Report Summary of Activities and Results Related to Adhesive Bonding, (2002)
The program at the California Institute of Technology on adhesive bonding has several objectives which are related to improve the design/analysis capability for the durable application of bonded...
An Experimental and Analytical Program to Develop Crack Tip Fracture Criteria. (2002)
Schultheisz,C., Ungsuwarungsri,T., Knauss,W. G.
A summary of progress on the development of instrumentation to determine with great accuracy the in-plane and out-of-plane surface deformations in the vicinity of a crack tip. The purpose is to...
An Experimental and Analytical Program to Develop Crack Tip Fracture Criteria. (2002)
A summary of progress on the development of instrumentation to determine with great accuracy the in-plane and out-of-plane surface deformations in the vicinity of a crack tip. The purpose is to...
Case Liner Bond Analysis. (1998)
Francis,E. C., Deverall,L. I., Carlton,C. H., Zitzer,H. J., Knauss,W. G.
A second generation finite element computer code was developed with specialized features for accurate evaluation of solid propellant case liner bond regions. The code uses six-term quadratic elements...
Workshop on Dynamic Fracture Held at Pasadena, California on 17-18 February 1983. (1998)
Knauss,W. G., Ravi-Chandar,K., Rosakis,A. J.
This workshop was proposed to provide a forum for the discussion of problems to be overcome and research to be undertaken in the future in the area of dynamic fracture. Fundamental aspects of the...
An Experimental and Analytical Program to Develop Crack Tip Fracture Criteria. (1998)
Schultheisz, C. R., Knauss, W. G.
The large plastic deformations at the tip of a crack in a ductile heat treatment of 4340 steel are studied numerically and experimentally. The numerical simulation of the experiment uses a small...
Time Dependence in Fracture Mechanics of Adhesive Joints and Composites. (1998)
The research program covered in this report is concerned with understanding the time dependent effects involved in the failure of polymer based adhesive joints and in advanced composites. The...
Development of Constitutive Behavior of Materials for SDRW's. (1998)
This investigation was part of a failure analysis project concerned with repeated malfunctioning of sonar windows installed on vessels and submersibles. The problem encountered was the gradual...
Visualization of Impact Damage of Composite Plates by Means of the Moire Technique. (1998)
Knauss, W. G., Babcock, C. D., Chai, H.
The results of a program to determine the phenomenological aspects of the propagation damage due to low velocity impact on heavily loaded graphite-epoxy composite laminates are described. The main...
Fracture and Failure at and Near Interfaces Under Pressure (1998)
This work addressed the failure behavior of solid propellant rocket fuels through crack propagation. The objective of the study was to: (1) develop the means for measuring large deformation fields...
This program sought to determine the time-dependent (viscoelastic) response of an elastomer at various temperatures to be able to construct the uniform master relaxation response, from which the...
Time Dependent Fracture and Cohesive Zones. (1998)
The following report is on the fracture response of material which develops cohesive or bridging zones at crack tips. crack stability as a function of the law which governs the interrelation between...
Dynamic Behavior of Brittle Materials. (1997)
Ahrens, T. J., Knauss, W. G., Ravichandran, G.
The objective of this work aimed at understanding the dynamic response of brittle materials under high rates of loading which are typical of high speed impact and shock generation. Three areas of...
Improvements are proposed in the application of the Digital Image Correlation method, a technique that compares digital images of a specimen surface before and after deformation to deduce its...
Improvements are proposed in the application of the Digital Image Correlation method, a technique that compares digital images of a specimen surface before and after deformation to deduce its...
Washabaugh, Peter D., Knauss, W. G.
Following earlier observations of multiple micro-crack formation accompanying crack propagation under dynamic conditions, the question regarding the discrepancy between the ‘theoretically...
Submicron Deformation Field Measurements II: Improved Digital Image Correlation (1994)
This is the second paper in a series of three devoted to the applicaiton of Scanning Tunneling Microscopy to mechanics problems. In this paper improvements to the Digital Image Correlation method are...
Submicron Deformation Field Measurements II: Improved Digital Image Correlation (1994)
This is the second paper in a series of three devoted to the applicaiton of Scanning Tunneling Microscopy to mechanics problems. In this paper improvements to the Digital Image Correlation method are...
Non-steady, periodic behavior in the dynamic fracture of PMMA (1993)
Washabaugh, Peter D., Knauss, W.G.
A crack moving dynamically through a sheet of Polymethylmethacrylate at high average velocity is found in reality to propagate in a non-steady, periodic, and perhaps discontinuous fashion. The...
A Mechanical Model for Elastic Fiber Microbuckling (1990)
A two-dimensional mechanical model is presented to predict the compressive strength of unidirectional fiber composites using technical beam theory and classical elasticity. First, a single fiber...
Time Dependent Fracture of Polymers (1989)
The fracture behavior of polymers is reviewed with emphasis on the time dependent aspects of the problem. Following a delineation of the history of crack propagation investigations in linearly...
Observation of Damage Growth in Compressively Loaded Laminates (1983)
Chai, H., Knauss, W. G., Babcock, C. D.
An experimental program to determine tie phenomenological aspects of composite-panel failure under simultaneous compressive n-plane loading and low-velocity transverse impact [C-75 m/s (0-250 ft/s)]...
On the hygrothermomechanical characterization of polyvinyl acetate (1980)
As a part of a program to understand the mechanisms of failure in time-dependent adhesion and film bonding, the creep compliance of polyvinyl acetate (PVAc) in shear has been determined both as a...
In order to gain an improved understanding of the behavior of human intervertebral disc material under various kinds of loads the viscoelastic properties of small specimens excised from human L4-L5...
Hygroviscoelasticity of the Human Intervertebral Disc (1980)
In order to gain an improved understanding of the behavior of human intervertebral disc material under various kinds of loads the viscoelastic properties of small specimens excised from human L4-L5...
Panagiotacopulos, N. D., Bloch, R., Knauss, W. G., Harvey, P., Patzakis, M.
The human intervertebral disc is a highly inhomogeneous fiber composite pressure vessel. If damaged in the post-infant stage, the disc does not repair and may need surgical correction. Diagnosis of...
Panagiotacopulos, N. D., Bloch, R., Knauss, W. G., Harvey, P., Patzakis, M.
The human intervertebral disc is a highly inhomogeneous fiber composite pressure vessel. If damaged in the post-infant stage, the disc does not repair and may need surgical correction. Diagnosis of...
The Fracture Energy and Some Mechanical Properties of a Polyurethane Elastomer (1971)
The energy required to form a unit of new surface in the fracture of a polyurethane elastomer is determined. The rate sensitivity of the material has been reduced by swelling it in toluene. This...
Stable and Unstable Crack Growth in Viscoelastic Media (1969)
The failure of load-bearing structures by fracture is generally important in all phases of our society. It may concern small household items as well as expensive structures of civil or space...