Research study on materials processing in space experiment number M512

Adhesion of the melted metals to the adjacent solid metals, and cohesion of the liquid metal to itself appeared to be equally as strong in zero gravity as on earth. Similar cut edge bead periodicity in cut thin plate, and similar periodic chevron patterns in full penetration welds were seen. The most significant practical result is that the design of braze joints for near zero gravity can be very tolerant of dimensional gaps in the joint. This conclusion is based on a comparison of narrow, wide and variable gap widths. Brazing is very practical as a joining or repairing technique for metal structures at zero gravity. The operation of the hardware developed to locate successive small (0.6 cm) diameter cylinders in the focus of the battery powered EB unit, melt the various metal specimens and deploy some liquid metal drops to drift in space, was generally successful. However, the sphericity and surface roughness were far from those of ball bearings

Fatigue of Yttria-Stabilized Zirconia: II, Crack Propagation, Fatigue Striations, and Short-Crack Behavior

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65604/1/j.1151-2916.1991.tb04089.x.pd

Tensile Creep and Creep-Recovery Behavior of a SiC-Fiber Si 3 N 4 -Matrix Composite

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65802/1/j.1151-2916.1993.tb03753.x.pd

Plasticity-Induced Fatigue Damage in Ceria-Stabilized Tetragonal Zirconia Polycrystals

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65141/1/j.1151-2916.1994.tb07093.x.pd

Tensile creep behaviour of a fibre-reinforced SiC-Si 3 N 4 composite

The tensile creep behaviour of a SiC-fibre-Si 3 N 4 -matrix composite was investigated in air at 1350 ‡C. The unidirectional composite, containing 30 vol % SCS-6 SiC fibres, was prepared by hot pressing at 1700 ‡C. Creep testing was conducted at stress levels of 70, 110, 150 and 190 MPa. An apparent steady-state creep rate was observed at stress levels between 70 and 150 MPa; at 190 MPa, only tertiary creep was observed. For an applied stress of 70 MPa, the steady-state creep rate was approximately 2.5×10 −10 s −1 with failure times in excess of 790 h. At 150 MPa, the steady-state creep rate increased to an average of 5.6×10 −8 s −1 with failure times under 40 h. The creep rate of the composite is compared with published data for the steady-state creep rate of monolithic Si 3 N 4 .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44708/1/10853_2004_Article_BF00543607.pd

Finite element modelling of creep deformation in fibre-reinforced ceramic composites

The tensile creep and creep-recovery behaviour of a unidirectional SiC fibre-Si 3 N 4 matrix composite was analysed using finite element techniques. The analysis, based on the elastic and creep properties of each constituent, considered the influence of fibre-matrix bonding and processing-related residual stresses on creep and creep-recovery behaviour. Both two- and three-dimensional finite element models were used. Although both analyses predicted similar overall creep rates, three-dimensional stress analysis was required to obtain detailed information about the stress state in the vicinity of the fibre-matrix interface. The results of the analysis indicate that the tensile radial stress, which develops in the vicinity of the fibre-matrix interface after processing, rapidly decreases during the initial stages of creep. Both the predicted and experimental results for the composite show that 50% of the total creep strain which accumulated after 200 h at a stress of 200 MPa and temperature of 1200°C is recovered within 25 h of unloading.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44717/1/10853_2004_Article_BF00576283.pd

Hyperconductivity in chilled beryllium metal

It is shown that in the vicinity of 77 K beryllium has a superior specific conductance compared with the nominally excellent metallic conductors aluminum and copper. It is concluded that beryllium should be considered for some conduction applications, despite its well known toxicity problems

Mechanical failure of cemented femoral total hip replacement

A review, with 17 refs. Factors which affect mech. failure of cemented femoral total hip replacement, i.e., external load, materials, geometry, and interfaces, are discussed

Validation of the Illness Perception Questionnaire for Schizophrenia in a German-speaking sample of outpatients with chronic schizophrenia

&lt;b&gt;&lt;i&gt;Background:&lt;/i&gt;&lt;/b&gt; Because the mere definition of insight from the therapist’s viewpoint may not be sufficient to identify treatment targets for adherence enhancement, we need assessment strategies which are more sensitive to the patient’s perspective. Illness perception (IP), defined as the beliefs a patient holds about his/her health problems, has been shown to affect coping in the context of a physical or mental illness, e.g. compliance behaviour. To assess IP in people diagnosed with schizophrenia, the Illness Perception Questionnaire for Schizophrenia (IPQS) was developed. The aim of the present study was to analyse the psychometric properties of the German version of the IPQS. &lt;b&gt;&lt;i&gt;Sampling and Methods:&lt;/i&gt;&lt;/b&gt; The study sample consisted of 128 German-speaking outpatients suffering from chronic schizophrenia or schizoaffective disorder. To achieve comparability with the validation of the English scale version, the same constructs were assessed: psychopathology, depression, and beliefs about medication. Furthermore, insight into one’s illness was assessed. Internal consistency, test-retest reliability and construct validity including convergent and discriminant validity were analysed. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; Five of eight IPQS subscales were found to be internally reliable and all subscales demonstrated high stability over time. Correlations with validity measures indicated that the subscales assess dimensions of a construct, which is distinct from psychopathology, depression, beliefs about medication and insight, except for the &lt;i&gt;Identity&lt;/i&gt; subscale which substantially overlapped with measures of insight. &lt;b&gt;&lt;i&gt;Conclusions:&lt;/i&gt;&lt;/b&gt; The German version of the IPQS is an essentially reliable and valid measure of IP for German-speaking people with a schizophrenia spectrum disorder. This may encourage its usage in further studies investigating the impact of subjective beliefs about mental health problems on outcome and recovery in schizophrenia.</jats:p